Heat pump sales outpaced gas furnace sales in the US in 2022 | Hacker News Reader

Heat pump sales outpaced gas furnace sales in the US in 2022

electrek.co

347 pointsmfiguiere253 comments

I recently learned from an NPR piece that only about 13% of US households have a heat pump.

This floored me. One because in my mid Atlantic area nearly every house has a heat pump. When house shopping many years ago we never saw a listing that didn't have one.

The other is that if you have central air then it seems like you should have a heat pump. You're basically just running the heat pump backwards to provide heat instead of air conditioning, but apparently the vast majority of central air installs are only set up to do cooling? This makes no sense to me. Even if you area gets too cold to be efficiently warmed by a heat pump in the winter you can still use it for several months out of the year and switch to gas only when you need to. It's not like gas is especially cheap.

Misaligned incentives. A traditional furnace is a bunch of sheet metal, a burner, a fan, and a thermostat and that's it. Sold for thousands, it seems like enormous, criminal markup. Of course they'll keep selling that and price it less than heat pumps, which have an actual complex closed loop coolant system in addition to what a furnace has.

https://www.rewiringamerica.org/ira-fact-sheets

Progress is being made.

> The 25C and 25D tax credits incentivize household electrification by lowering the total cost of qualified electrification upgrades. 25C provides a capped 30 percent tax credit for heat pumps, heat pump water heaters (HPWHs), qualifying electrical panel upgrades, select weatherization measures, and energy audits. For the first time, air source heat pumps for space heating/cooling and HPWHs will be eligible for a tax credit of up to $2,000 per year, and electrical panel upgrades installed in conjunction with a heat pump or HPWH will be eligible for a tax credit of up to $600.

There are a lot of US households on places like New England and the Midwest where historically very very few houses have central air and most have a furnace running on oil, propane, or natural gas. The upgrade path is hard there: do you accept the multiple thousands of dollars to install a heat pump on top of your existing heating solution? For the couple of fringe months where a heat pump can actually heat your house, and the extra cost of cooling in the summer (money many don't have)?

It probably makes a lot of sense to just switch to a heat pump if you live in the south these days and give up any backup heating system entirely. But it is worth noting that only in the past 5 years or so did we finally get heat pumps that didn't totally suck at 0C. Until then, it made sense for even a lot of Southern households to stick with backup furnace + central air, assuming they already sunk money into the backup furnace for the 5 days a year they actually need it.

Heat pumps have always had a built-in resistive heating element as a backup option for when it gets too cold out. This is terribly energy inefficient, but if you're talking about a few days a year at most it is fine, no need to install a second heat source.

Besides, 0C is far too conservative an estimate for heat pumps. -10C was no problem even for 30 year old units.

> Heat pumps have always had a built-in resistive heating element as a backup option for when it gets too cold out. This is terribly energy inefficient, but if you're talking about a few days a year at most it is fine,

Won't it be a problem if heating becomes much less efficient across an entire city, just as demand for heat is at its highest?

Indeed! In NC this past January, Duke Energy asked everyone to turn their thermostats down. NC has the one of the highest percentages of heat pumps in the country:

https://news.duke-energy.com/releases/duke-energy-thanks-cus...

https://www.canarymedia.com/articles/heat-pumps/chart-which-...

Large parts of the country can be consistently below 0C for weeks at a time. Resistive heating cannot beat gas in that scenario.

True, but conversely a decent swath of the US population lives in Texas, where being under 0C for weeks at a time is a near impossibility. For those use cases heat pumps work great (assuming you don’t have a failed state on its own grid that will fall over at the slightest whiff of abnormality, of course).

Modern air source heat pumps will not be using resistive heating in most winter weather across the USA.

A Mitsubishi Hyper unit still has a COP of 1.0 at 5F.

Resistive heat has a COP of 1.0.

So that heat pump loses its advantage at 5 ⁰F.

I didn't say that they still had an advantage, I said that switching to resistive heat was unlikely for most winter weather across most of the US.

"Still has a COP of 1.0" implies it is still doing something is all.

It would be clearer to just say that it works down to 5.

I'm not in the coldest regions and would be using resistive heat many nights of 3 months with that performance.

Mitsubishi's approach is to avoid resistive heating, and instead drop COP to 0.85 at -13F

If the unit is sized correctly, this will provide adequate heat, albeit less efficiently than resistive heating would. If you live in an area where most of the heating hours are at 5F or below, yes, resistive would make more sense. But where is that?

I'm in that situation -- oil burning furnace with forced air. It's a 1980s vintage system with an outdoor double walled oil tank.

I could replace the furnace with an air source heat pump.

But it turns out the people in the 1970s who designed the system weren't really on-the-ball. There's insufficient return, it's not balanced such that it's way hotter upstairs than down, etc.

Further, if I wanted to blow cold air through the system I'd probably collect lots of moisture on the vents because it gets humid in the summer.

The solution, though, is multi-zone mini splits that just pump the refrigerant around and expand / compress it where I want the heat/cooling; that gets rid of the big noisy air handler, allows my system to be a multi-zone system, and generally seems like a much better design.

And with modern heat pumps, I don't think even in new england I'd need backup resistive heating.

Though not in the US, Elliot Lake, a planned uranium mining community turned retirement village was built around the “nuclear model” of electricity production — ie that a base load was always available.

Many houses in the community still have their 1970s-era heat pumps.

> For the couple of fringe months where a heat pump can actually heat your house

Heat pumps can heat throughout the entire winter in most of New England. The idea that they can’t keep up when it gets cold just isn’t true with new technology.

New England had a day and a half or so this earlier this year where temperatures got as low as -10F (F, not Celsius). Afterwards a newspaper did an informal poll of heat pump owners. The overwhelming majority (IIRC 90%) of respondents said their heat pumps kept up fine. Keep in mind not all of these installs were the latest and greatest tech either.

Insulation is probably the more important factor. If you don't lose too much heat to the outside, the heat pump doesn't even have to do that much. Or any other heat source, for that matter.

Good point. Most of New England is just not that cold any more.

Where I live in Northern New England, we got down to -20, almost -30 during that cold snap. And had a lot of sustained 0-ish temps throughout the winter. I wouldn't be comfortable using only a heat pump as a fuel source in my 1800s house. But I suspect it would likely keep the pipes from freezing.

My relationship might not survive it, though. Better to keep the propane heat source for now :)

Counter anecdote. I just bought a house in the mid atlantic and 0 of the houses I looked at have a heat pump.

> The other is that if you have central air then it seems like you should have a heat pump. You're basically just running the heat pump backwards to provide heat instead of air conditioning,

These days sure. But the cold weather compatible heat pumps are relatively new, electricity was and still is a whole lot more expensive than gas, running it as both an air conditioner decreases its overall life span, and finally a dedicated air conditioner can be more energy efficient especially on older models.

When I was a kid in the 80s my house had an electric heat pump and the aux (resistive) heater coil didn't kick on until about 0F (-18C). You could tell because it smelled a bit when it happened, which was pretty rare. I guess it probably kicked in some more times overnight and I didn't notice, but overall the heat pump did the lion's share of the work.

Heat pumps have become much more efficient since then. I replaced an old and rusty unit on my first townhouse and cut the electric bill by $100-$200/month in the middle of summer and dead of winter.

Natural Gas heating is surprisingly good in practice, especially in the days where we only had fossil fuels on our electricity grid.

If you go fossil fuel, you have only 40% efficiency for Fossil Fuel -> Electricity, then Electricity -> Traditional heat is only 100% efficient. So 100W of chemical energy turns into 40W of electricity, and then turns into 40W of heating.

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Today, a Heat Pump can be like 200% efficient, so you 100W of chemical energy turns into 40W of electricity, then turns into 80W of heating from the heat pump.

Alas, a Gas Furnace is like 90% efficient (10% of the heat escapes in the steam / waste products that needs to be pushed out the chimney, but everything else turns into home heating). So your 100W of chemical energy turns into 90W of heating, and you're done. And that's why our infrastructure in the USA is so much around gas heating, because its better. Especially since we are very rich in domestic natural gas production.

Yeah, we're getting to the point where Heat Pumps + Solar Electricity are coming. But... we're not there yet. On today's grid, Natural Gas heating is likely the most efficient option.

EDIT: Got my units wrong. It should be 100J of energy, not 100W of energy. Watts are power. Though in USA, we don't use Joules for energy, but instead "BTUs". Whatevs.... I think my point is still clear :-)

>Today, a Heat Pump can be like 200% efficient, so you 100W of chemical energy turns into 40W of electricity, then turns into 80W of heating from the heat pump.

This isn't true today. The absolute minimum COP is 3.1 in the US.

https://www.pickhvac.com/heat-pump/basics/cop/

This appears to be the minimum for geothermal. The vast majority of heat pump installs would be air source, and while these can often get 3+ it’s highly dependent on climate and local grid efficiency.

It also depends on local prices. In Madison, WI our implied (not actual) electric grid efficiency based on prices is under 20%.

The energy.gov page has more details, it's 3.3 for air source at 47 deg F and a reasonable size:

https://www.energy.gov/eere/femp/incorporate-minimum-efficie...

Not for air source.

Source: your link.

Air source heat pumps are a lot easier, so they are the majority of installs.

I expect the national code doesn't give a minimum COP for air source because the performance changes with air temperature. The bulk of my heating cost occurs when it is 10-20 ⁰F outside, where someone located in a warmer spot might have most of their heating at 35-45 or whatever.

I definitely read it too quickly, but clicking through to the energy.gov page does clarify that the COP is measured at 47 deg F (which is warm)

You will not get the COP of 3 during most of the winter in the interior US with an air source heat pump. Their efficiency go down significantly once the temperature is below freezing, due to required thawing cycles, and because the bigger delta between inside and outside temperatures reduces pumping efficiency in general (efficiency is best when outside is not much colder than inside).

Air source heat pumps are really good tech overall, especially because they also double up as AC in summer. However, in winter, in a head to head comparison, they only handily win in areas with mild climate, like eg. all west, or much of southern US. In the northwest or midwest, they are unlikely to beat efficient gas furnaces.

Here's a heat pump that has a minimum COP of 2.93 at 5 F, and 9.42 (!!!!) at 47 F: https://ashp.neep.org/#!/product/56885/7/25000///0

Your point stands, but your 1,500 sqft home needs about 68,000 btus.

That heatpump would be for about a 300-400 sqft room.

Seems like a bigger one would only be more efficient.

Surprisingly, this doesn’t seem to be true for most of the split system ductless heat pumps (aka “reverse cycle air conditioners), I’ve seen.

The smallest ones are almost the most efficient ones in the range.

I’m not sure why this is, and whether it generalises to house-size ducted systems, but it’s pretty striking nonetheless because it’s the exact opposite of most heat related systems I can think of.

Might it be because the surrounding air only has so much heat in it?

Thus, smaller units, more spread out, have access to more heat?

I don’t know why - But your single air exchange heat pump driving a single head unit in the 9,000-12,000 range seems to be incredibly efficient. Once you go to a larger unit, and more heads, the efficiency drops.

It’s fascinating to even see the huge increase in switchable units - running your 4/5 ton unit at 4 tons is much more efficient. (Usually)

If you look at the numbers that's clearly not the minimum COP. I'm not sure what it is, I think it's the COP when operating at minimum power.

Look in the right most column for COP at max power

Cold weather heat pump technology is consistently getting better, but I also think people underestimate how many heating days are above freezing even in cold areas and how much of the US and other places is mild enough in the winter for heat pumps to be fairly efficient nearly every day during the winter (especially if you look at population rather than land area).

If you look at a place like Minneapolis, which is normally considered a pretty cold US metro area, you do have a few months where the average temp is below zero. But you also have several more months where the temperature is cold enough to turn on the heat but well above freezing, where a heat pump is dramatically more efficient. When picking a heating system, it makes sense to consider comparative efficiency over the entire year, not just performance during the worst conditions in the middle of winter. Even in a city like Minneapolis, it's not obvious that heat pumps are less competitive over the entire year, even if their performance in January probably isn't fantastic.

I also think the practical geographic area extends further than people think. New York City definitely isn't the south, but per some random Googling, it doesn't appear to have any months where the average temperature is below freezing. Even Boston only has 2 months that barely drop below freezing. Most of the US northeast (definitely the mid-atlantic) by population arguably also falls into the range where heat pumps make sense.

But then you need two systems - heatpump for most of the year, and natural gas for the cold days when you would die without it.

At least in Canada I’d need to know that my system can handle a week of -30 or -40C in my city. Some places are even colder, for longer at a time.

No, electricity is versatile, you can just make electricity into heat on that day when it's too cold for your heat pump. Resistive heating is not exciting > 100% efficiency technology, but it works and if you live somewhere that realistically gets too cold to run the heat pump that's what you add, not a whole gas burning system.

I don’t know why I didn’t think of that.

I guess the only remaining concern is that winter storms cause both cold weather and trees falling onto powerlines. The latter is rare though

Right, but (a) most modern gas fired heating actually requires mains electricity to function properly, so if you are blacked out your heating probably is disabled and... (b) even if the heating does work, a modern home is a pretty miserable place with no electricity, unless you know power will be back soon (hours or sooner) you should probably set out for a communal safe respite centre where everybody can work together to stay warm, feed and care for each other until the emergency is resolved.

There are people who genuinely live in the middle of nowhere, on an otherwise uninhabited island as caretaker, deep in the forest manning a fire watch tower, Antarctic research base, that sort o thing, who do need have more options, because if they run out of options they're dead. If you're in that situation you still don't necessarily want gas heating though, a fossil fuel powered generator might make a lot of sense, maybe even more than one, because again electricity is so versatile.

A snow storm plus power outage makes me want to bed down, not flee. The idea of leaving your house for a community center during a power outage is odd to me on several axes (pipes freezing, digging out your car, driving on half-plowed roads), especially in the hyper-individualist US (do these centers even exist?)

It's much simpler to obtain and fuel a small generator to power meta loads like thermostats/circulators/blowers than a large generator that supplies the thermal load. Fully committing to a heat pump as your only heating would likely involve a large gas generator fed by municipal gas or at least a large buried propane tank (for capacity and temperature).

The straightforward backup heat answer is wood. It's easy to obtain and store, and the primary drawback of it requiring labor and attention isn't a big deal during an outage. Although if you don't do it regularly and make sure your stove is in good order, lighting a fire during an emergency situation might not be the best idea.

So true, I'd much rather batten down the hatches, put my frozen food outside, and make sure none of the pipes burst.

I heard about a guy who had copper piping with water flow going around his chimney (on the inside) and then through the house.

That'd be a cool system if you could switch out the heat source, electric and an indoor-safe wood stove. Just get a CO monitor!

Actually, I just got a wood boiler for this past winter. This is basically a stove that lives outside, surrounded by a water jacket (~200 gallons) and insulation. It modulates the fire to keep the water from boiling off regardless of how much heat you're drawing off. You then run pipes to your house and tie it into your hydronic heating system. I feed it wood twice a day, and it keeps my house as comfortable as burning oil did (actually even more comfortable since I can heat the unfinished basement when I want, and not feel bad). And since it's outside, I don't deal with any of the mess or work of bringing heating-scale quantities of wood inside.

They do require power to run (automated dampers, blower, circulators), so I have a small backup generator as per my last comment. And they've gotten a bit expensive (especially now that the US federal tax credit has gone away), but my estimated payback period is around 6 years.

You might wonder why I'm posting in a thread about heat pumps when I just got a different major heating source, but I see heat pumps and wood as two very complementary heat sources. Down the line I'm planning to add a water-to-water or air-to-water heat pump for the shoulder seasons (and summer DHW), so that I don't have to tend a fire (or burn oil) when the heating load is low. One four or five ton unit should take care of my heat loss most of the time, and I won't have to oversize the system to handle the dead of winter cold snaps.

The only problem with that is if your electricity generation capability is correlated with the outside temperature. You don't want everyone turning on their resistive heat right when you have the minimum generation capacity.

I can’t reply to telaramex directly but backup electric resistance is exactly how my heat pump hot water works.

Geothermal is kind of amazing. We have a geothermal system that can get to 5.1 COP. We used 650 kWh for heat in December, which translates to 22 therms. The average household in my area uses roughly 110 therms per month for winter space heating.

Yup, I have a ground source heat pump, sometimes called geothermal - it is amazing! My neighbor has a slightly larger house, but close. Their bill one month was almost $500 and mine was $110.

It didn't cost that much more to install and there isn't any equipment outside in the weather.

My understand was geothermal installation is extremely costly due to the deep bores you need to dig. Or do you have enough land to go out instead of down?

Can you or the GP share more about the economics of your installations?

I've build 3 houses. For the first I had to get a bid for 3 bore holes, that was too much for me. I opted to insulate like crazy and use natural gas.

I didn't bother with a bid the second time because the situation was the same. Air source was really coming along at this point (at least in the US), I should have pushed harder to get it.

My current home has enough land to go horizonal. There are 4 trenches, 6 feet deep, 3 feet wide and 300 feet long. The pipe loops down and back on each trench. Excavation was about $1000 (full day for a man and a machine) and another $1000 to bury them and a day of labor to lay the plastic pipe and weld it together.

Equipment was about $8,000 more than my other options (no natural gas here), but after tax breaks it was about $3000 more. I think it was worth it, even if there weren't tax breaks. I really had to push hard to get this. I had to use a general contractor on this house and he swore it wouldn't work. I made the calls and found someone to do it.

The system runs often when the highs are -20f, but I've never flipped on the backup electric resistance heat.

During the summer the A/C is so cheap it is practically free. It doesn't take much compared to heating. Cooling might have to get the house 30 degrees less than the outside air, but heating has to raise the house nearly 100 degrees f warmer than the outside air.

Ground source is always my first recommendation, but air source should be more popular than it is.

A funny note about the builder who thought ground source wouldn't work well, he also tried to talk me out of a tankless hot water heater because the well water would be too cold in the winter! I guess he didn't understand that the ground down far enough is a pretty steady temperature.

> During the summer the A/C is so cheap it is practically free. It doesn't take much compared to heating. Cooling might have to get the house 30 degrees less than the outside air, but heating has to raise the house nearly 100 degrees f warmer than the outside air.

You can't rely on just comparing temperature differentials. During summer, the house receives a lot of extra heat in the form of sunlight.

It is true that air temps alone do not tell the whole picture, but my coldest winter days also tend to be clear skies and also have lots of direct sunlight. My summer days are also more overcast than one might expect.

It isn't my profession, but I've spent a fair amount of time tweaking building envelope and conditions in HVAC calculations to make decisions in how I build.

A delta of 30 vs 100 is not the only factor, but I'd bet in my case it is the largest factor. I still agree with your point of bringin up other factors. Even changing the direction a building faces can change the load on it.

The US Code vs the Carnot's theorem, who would win? The answer might surprise you!

But having a furnace means you also have central air. So the question isn’t furnace or heat pump, it’s furnace and one directional heat pump or just a heat pump. Yes, on cold days the furnace will be cheaper, but on most days the heat pump is cheaper and requires less maintenance since you’re turning two appliances into one.

Many places in heating-dominated climates do not have central air.

I’ve lived 35 years in New England and only one of those places (a modern high-rise) had central air.

Are we talking window unit plus radiator or just no cooling? For window + radiator heat pumps make less sense, but window unit heat pumps work well and are worth considering as a radiator replacement when the window unit is replaced.

Many have no cooling at all. Others have window shaker ACs only in bedrooms (which aren’t practical to use window heat pumps as a replacement for radiators since the heating balance would be terrible with the rest of the house and the air leakage around a window unit is really bad when the inside/outside delta-T is 60+°F in winter [versus ~15°F in summer])

Window units in practice are "no cooling until there's a heat wave half way through July that prompts you to actually install them".

Uhm. The entire midwest is almost as cold as New England (or colder) and yet has widely installed A/C to deal with hot humid summers.

Modern (i.e. non-adobe, non-stone) construction in the higher-altitude mountain west has similar issues (without the humidity).

New England is really the exception to the rule, not the rule (it's a lovely, lovely exception though).

It was a bit weird when I lived in SoCal. It was the only housing I've lived in without AC. It only got uncomfortable for about a week out of the year, most of the time the ocean winds cooled the air off enough. I can't imagine going without AC living in the midwest and the winters can be absolutely brutal on top of it.

FWIW, modern heat pumps can exceed 400% efficiency, so the math is starting to work out in their favor even for fossil fuels burned at a power plant.

You're at the low end for heat pump efficiency, but more importantly, you're overlooking the fact that the fossil fuel usage of heat pumps benefits from the ability to use electricity generated by non-fossil fuel sources. In the US that's a significant fraction of electricity generation and in many places it's the majority of electricity. The ability to combine the electricity produced by chemical energy with nuclear, hydro, solar, wind, etc, gives heat pumps an significant advantage over directly burning fossil fuel for heat if what you care about is fossil fuel usage.

Renewable fuel sources are already nearly 100% in use. So if you add electricity demand, that new demand usually comes from fossil fuel. That is, you need to consider marginal electricity generation.

At worse, it’s replacing natural gas with fossil fuel. At best, it increases demand so more renewables are built.

Heating and AC are unlikely to be powered by renewables, because they're highly correlated and bursty.

Ex: Your town might be fine with 100MW of power at 60F. But if the temperature drops to 40F, everyone turns on their heaters more, so the entire town uses 150MW or more. So how much renewables do you build? Not 100MW, but 150MW. Which is absurd, no one is going to overbuild capacity like that. And even at 150MW, if the temperature drops to 20F or 10F, even more energy will be used.

In contrast, the Fossil Fuel / Natural Gas peaker methodology is to overbuild on capacity, because capacity is extremely cheap. Maybe the town has a 200MW plant for example. You only use what the people need, so the 200MW plant consumes 100MW at 70F, 150MW at 40F, and everyone has capacity left to grow and expand the town.

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Renewables are great for baseload / constant loads that are predictable. But weather isn't always predictable. In this example, 100MW of baseload renewables would be ideal, and the gas-peaker plant is used for everything in addition to that.

You're drastically overstating the case. No, it does not make sense to treat the entirety of heating as non base load (with your anchor of "60F").

On the scale from predictable to not predictable, heating loads are somewhere in the middle. For a given night that ends up having a low of 10F, it would be hard to know that exactly ahead of time, but we have a pretty good idea that it will be below 20F. So that's roughly only (65-10)/(65-20) - 1 = 22% additional heating load that wasn't predictable.

Plus HVAC is highly dispatchable - if there is excess electricity that needs to be used, heating an X-to-water heat pump's storage a few extra degrees is a perfect place to use it.

You're dramatically underestimating the swing of electricity in practice.

https://www.caiso.com/TodaysOutlook/Pages/default.aspx

See September 22, 2022. California required 51,000+ MW of power capacity as the state reached record high temperatures. Just a few days earlier on Sept. 9th, 42,000 MW was all that was needed.

See Yesterday: March 31st 2023. California only required 26,000 MW of power capacity. Even then, the low for March 31st was 17,000 MW at midday.

Given these stats from the last year... How much baseload should California build out? And how much "peaker" production should California have?

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The weather swinging +/- more than expected can cause 10,000MW (or 20% shifts) in power in just a couple of days. Seasonal differences are +100%/-50% differences in power capacity.

Its because of this that natural gas peaker plants are used. That's why H2 fuel, as inefficient as it is (but a potentially green source) is still being considered. Having day-to-day, or seasonal, storage of power through the use of chemical energy storage is one of the most promising technologies to tackle this problem.

You've switched from talking about heating (presumably in climate that needs a significant amount), to talking about cooling California.

I'm not versed in exactly how these numbers shake out to be making informed conclusions, but by your previous argument it doesn't seem like you are either. For example cooling load is going to be positively correlated with solar output. More bursty renewables (solar, wind) means less base load and more peaker plants to handle their droops. And just because a town builds one "200MW peaker plant" doesn't rule out adding renewables (and making the peaker burn less gas), even though the renewables only operate at their full capacity a small part of the time. The only way to figure out what to make sense is to tradeoff specific capex/opex/utilization/revenue, rather than talking in wide-sweeping generalizations.

Storage is the general solution to the problem, yes. The easy form of storage that we've become accustomed to is the chemical energy of natural gas. Another is end-user thermal storage, where consumption is accelerated/delayed depending on what the grid needs. Moving away from fossil fuels requires figuring out storage, especially how to utilize the inherent storage/slack we already have, rather than continuing to just take fossil fuels' convenient advantages for granted.

> doesn't rule out adding renewables

I never was against adding renewables. I'm simply pointing out rough estimates on our electricity usage throughout the year, and throughout the day.

Peaker plants, unfortunately, seem like the best solution. Natural gas is the best peaker plant for a variety of reasons. But then natural gas piped to a house for near 100% conversion efficiency is even better (rather than taking rather dramatic hits on conversion inefficiencies). Therefore, Natural Gas in homes is surprisingly useful, and will remain so for the foreseeable future.

We absolutely should be building renewables for the near and moderate terms. We don't have enough renewables for baseload yet.

> You've switched from talking about heating (presumably in climate that needs a significant amount), to talking about cooling California.

California has public electricity usage patterns. For better or worse, its the best data that we've got. I assume its somewhat representative of the energy requirements across the country.

Other parts of the country its way more complex because there's natural gas flowing everywhere. So its harder to convert Natural Gas heating vs electricity prices. Nonetheless, the concept of "This differs based on the weather" and "The weather changes dramatically every week" is universally true.

I wasn't saying you yourself were against renewables. Rather your argument seemed to imply that building one big peaker plant would preclude the demand for renewables since the peaker could supply the entire load all the time.

I don't think we'll ever have "enough" solar+wind to supply base load, since night exists and winds calm down. Talking about "renewables" as a group doesn't really make sense. For example hydro is highly consistent and highly dispatchable, but waterfalls are rare.

Spitballing, I would think cooling (especially with California's coast where it's rarely needed) would have much higher variability than heating, since people seem to tolerate a wider range of higher temperatures compared to colder temperatures. At least from personal experience once I enable the heat for the year it mostly stays that way, turning on when it gets even a degree too cold. Whereas air conditioning is a question each day of "can I get by with the windows open", and only when the answer turns out to be an unequivocal "no" do I turn on the AC (which then runs continuously to make up for lost time).

Natural gas is a fossil fuel

We need to go to zero and gas furnaces cannot. (Horribly inefficient synthetic fuels excluded.)

In that context current electricity generation does not matter. It‘s an infrastructure change that allows for future zero emissions. Just like EVs.

We're at like 12% renewable. The journey from 12% renewable to 30% renewable will be different than the journey from 90% to 100% renewable.

The tools in our disposal to reach 20% or 30% are available today, if we can understand them. And also, as long as we don't let perfection be the enemy of good.

We will probably never tackle the 90% to 100% problem in our lifetime. It is best to focus upon the problems that are in front of us, and that we can in fact solve or fix within our lives.

We need to get to zero. Burning gas doesn’t get us to zero. That’s the issue.

Given the lifetime of gas furnaces and what we know about climate change it is madness to even consider using them in brand new construction now.

Gas was and is the right tech for transitioning. But you seem to be stuck in the 90s or early 2000s when that kind of policy would have made sense. It’s too late and getting later.

You lose a lot of heat due to improper insulation or in the case of northern california, no insulation whatsoever.

> Alas, a Gas Furnace is like 90% efficient (10% of the heat escapes in the steam / waste products that needs to be pushed out the chimney, but everything else turns into home heating).

And there exists even more efficient options today. Like high efficiency furnaces that use the heat from the flue in a second heat exchanger to bring it closer to 99%

> If you go fossil fuel, you have only 40% efficiency for Fossil Fuel -> Electricity,

This is a big underestimate for natural gas now that we mostly use combined-cycle gas plants (basically a jet turbine bolted to the ground, with its exhaust heat used to power a traditional steam plant). Combined-cycle efficiency is over 60%, which changes your math significantly.

more importantly, decoupling the electricity generation with the heating, means that improvements made to electricity generation instantly flows into each home, vs using gas for home heating means _every home_ would need to purchase new gas equipment if improvements become available, to get the improvements - a major capital cost for the individual which may not be able to do it.

Ant then you have combined cycle + district heating plants, and you use even more of the energy.

Got all your numbers wrong too, not just your units. Modern combined cycle power plants mean that 100 J of chemical energy turn into more than 40 J of electricity (depends on your energy mix, but could be as high as 60 J). Then you also get a third of your energy from nuclear in some places, or hydro, or solar and wind (that is happening now - not just in the future). Heat pumps can be 300% or 400% efficient for most of the year (it's those few coldest nights of the year where they really struggle).

So even if you don't have any nuclear or renewable energy in your mix, just natural gas, you get 60*3 or 4 = 180 to 240 J of heat energy from your 100 J of chemical energy.

For most people in America, heat pumps are currently the most efficient option.

You're focusing on "today" when this is a twenty or thirty year machine. Twenty or thirty years from now a gas furnace will still be a 100% emitter. A heat pump has the ability (without upgrades) to move an increasing quantity of the energy to renewables.

A modern natural gas power plant has over 60% efficiency of electricity generation. 40% is for rather old ones or those used for peak, not base load. But even those are improving.

Moreover, using natural gas at home for heating is not 100% efficient. Some heat is lost with exhaust plus not everything is burned. A good furnace with proper heat exchanger is about 90%, but cheaper ones can be below 80%.

So even if your electrical heat pump is just 200% efficient and the electricity comes from a gas power plant, it is already a win compared with a gas furnace at home.

Both with electricity and gas there are transmission losses, but they are roughly the same and with electricity we know how to make them smaller long-term.

Heat pump's coefficient of performance is more like 3 to 5.

Most traditional natural gas heat is only 80% efficient since you have wasted exhaust heat. If you had a air pump you can achieve up to 92%-95% efficient, but with the added cost and complexity of having an electric fan.

I'm in NJ just west of Manhattan and I could not make the numbers work at all. I have averaged about $1.05 a therm for gas and my heat bills are very low even in Jan/Feb. On the other hand I pay 16.5 cents /kwh for electric.

I ran the numbers through a spreadsheet and I would be paying an extra $100 a month for heat and an initial cost of 10k more for the install, and the ac side would have a slightly lower seer than the best ac systems available.

I would need a COP of 5 for a heat pump to be more efficient. They don't exist for air source. I live in a brownstone/townhouse and while geothermal is theoretically feasible ( I have a small yard) I called every installer I could find in the tristate and none would attempt it.

I was immensely disappointed but I cant be paying more upfront and ongoing. If I had solar it would be a bit better but last time I attempted it I only got 2 bids out of the 30 installers I called and then COVID hit. The numbers weren't especially encouraging. I can't get that many panels on my roof due to firecodes.

To be clear, in your case the heat pump would use less energy, and thus would be more efficient. Your complaint is that it would cost more to use less energy, which is true. As long as natural gas is 3x cheaper than electricity per kWh there isn’t a good incentive to switch to heat pump heating for the part of the country that experiences a cold climate.

Yep, grew up in that area in a house w/ a heat pump. However it also had oil furnace (aka diesel) to supplement as it’d get down in the teens during coldest parts of winter. Also stacked, dried, carried in and burned a fair amount of firewood growing up.

> However it also had oil furnace (aka diesel)

I've never heard that before; where did you grow up where an oil furnace is also known as a diesel?

> This floored me. One because in my mid Atlantic area nearly every house has a heat pump. When house shopping many years ago we never saw a listing that didn't have one.

Is this really possible? Is every house in this area less than 20 years old, or occupied by a well-heeled and environmentally conscious homeowner?

That area us probably TVA or.other place near that territory where electric is very cheap. So of course heat pumps are popular, they don't have much gas infrastructure, and evem where it exists heat pumps have been cheaper for decades.

It is the Northern Virginia suburbs. The homes I was looking at were mostly built in the 80s-90s because that's roughly the band of growth where I could afford to buy.

Interestingly enough, gas was something of a premium feature. It was generally just used for the water heater and range. The homes with gas were out of my price range.

Technically, if you own a fridge, you actually do have a heat pump. And it is heating your house slightly. But using heat pumps for heating has not been that common until fairly recently. So 13% is actually pretty good.

Using fossil fuels for heating has historically been quite cheap until that started changing a few years ago. For the same reason, building codes in the US are kind of sloppy when it comes to e.g. insulating houses properly. You can save quite a bit of energy if you fix that but until recently energy was cheap enough that a lot of people could not be bothered to care about that. Running the AC in a leaky house with single pane glass is kind of insane if you think about it. Yet, that seems to be standard practice in a lot of places in the US.

Only if you stick your fridge in your doorframe and vent it outside. Otherwise it’s just a resistive heater. :)

> This floored me. One because in my mid Atlantic area nearly every house has a heat pump. When house shopping many years ago we never saw a listing that didn't have one.

In California, especially Southern California, many homes still have wall-mounted natural-convention gas heaters. Mainly because natural gas is plentiful (LA is basically sitting on top of an oil and gas reservoir) and heating isn't needed much of the year. Often they are placed in/on a wall between the two largest rooms, so that both are heated.

The technology is actually pretty neat: A thermopile sits in the pilot light's flame, which provides electricity to hold open the main shutoff solenoid valve and run a thermostat, so it needs no external electricity.

I have childhood memories of shivering in front of a gas wall heater during cold winter days in Palo Alto. I was visiting from Vermont (which was much colder, but houses were equipped for it) and those days gave me a new appreciation for the cold.

> I recently learned from an NPR piece that only about 13% of US households have a heat pump.

I wonder what the % of US population even needs a good heater.

There’s a lot of people who live in TX, SoCal, Florida etc that minimally use their heater.

Some quick Googling fails to find a good answer, but I'd venture to say that a significant majority of the US population lives in places with mild enough winter weather for heat pumps to be practical even without good cold weather heat pump technology. The northern interior US, where the coldest winters tend to be, covers a lot of area but is pretty sparsely populated compared to the coasts and the south, probably in part because most people don't like frigid winters. Arguably human temperature preference is actually ideally suited to favorable heat pump conditions.

Here in the Chicago area, natural gas is piped in underground, and for the most part, the electrical infrastructure is above ground, and thus vulnerable to ice and the errant vehicle taking out a pole.

Thus, the risk of losing electric power is the highest at the time you would need it the most if you relied solely on a heat pump to keep your house warm, and your water pipes from freezing and then damaging everything. This is a very strong incentive to have natural gas heat, and a small generator to be able to run the fans to operate it. (Or perhaps a large UPS rated for inductive loads)

I think a gas operated backup generator that could then exhaust it's waste heat as input to a heat pump would be the best of all worlds.

Most of the time, it serves as insurance. On really cold days (it has gotten down to -40 in my lifetime), or when power is out, it could both run the heat pump, and serve as the "emergency heat" sometimes required for an air-source heat pump.

Of course it would be better to have a ground loop heat pump, but that's not always an option.

> You're basically just running the heat pump backwards to provide heat instead of air conditioning

It is absolutely not that simple. Even a passing knowledge of heat pump technology as actually implemented would dispel that simplistic idea.

For example, one of the biggest issues to contend with is condensation. Making your outside fan unit cold instead of hot will quickly destroy it due to moisture accumulating in ways that were not expected.

Which is why every heat pump has a defrost cycle. Also why every heat pump has the resistive heater backup. If you lose power for a long time when it has been very cold the system has to be very careful when it starts back up, using the resistive heater to warm the refrigerant and coils to make sure they have not frozen up.

But this is all software and is a solved problem.

The people mining fossil fuels are very well connected and shaped US History to sell you hydrocarbons.

A/C without a heat pump is insanity. It's literally the exact same appliance with an added reversing valve and associated piping. A few extra dollars and your air conditioner can also heat. Mind blowing that anyone wouldn't choose heat pump. Poor education/awareness I guess.

There's an amazing video on heat pump from Technology Connections: https://www.youtube.com/watch?v=7J52mDjZzto

That's the right one to start on, but he's posted a few followups with updates and more information: https://www.youtube.com/playlist?list=PLv0jwu7G_DFVIot1ubOZd...

I very nearly bought a heat pump for my house to replace (or augment) my natural gas furnace, but was dissuaded by the salesperson.

He who pointed out that, while heat pumps are miracles of efficiency, the electricity in my area is primarily generated by burning fossil fuels such as coal and natural gas. Due to transmission losses, it is cheaper, efficient, and greener to combust natural gas for warmth directly than to burn it at a power plant, feed the power into the grid, and use grid power to run a heat pump.

Of course, running a heat pump allows you to take advantage of greener power sources when they become available, but his claim was that in a lot of places they don't really benefit the environment right now. Anyone have any numbers to back this up or refute it?

I would just use heat pump for convenience alone. Not having monoxide and NOx risks around the house is another one.

> Due to transmission losses, it is cheaper, efficient, and greener to combust natural gas for warmth directly than to burn it at a power plant, feed the power into the grid, and use grid power to run a heat pump.

That would certainly be true for a classic electric (element) heater, but I thought the point of heat pumps was that they’re not generating heat just… pumping it.

I'm not convinced either a heat pump has a cop of ~4. A thermal power plant is ~50% efficient and transmission isn't losing 50% of the energy. This also ignores any greening of the grid, present and future. And the fact that a furnace/boiler isn't 100% efficient.

> A thermal power plant is ~50% efficient

For electricity alone, I'd want to add. With heat coupling and district heating, thermal power plants can reach ~90% efficiency.

He's probably ignoring the externalities like the gas leaks on the way to your house or the power plant being able to have a huge scrubber that reduces emissions compared to what you can have at your house.

The most important reason is there was probably a financial incentive from the manufacturer of the gas/oil furnace that made it more profitable for him to sell you that.

Here we have such a massive state rebate on heat pumps, you have to literally have a lot of money and politics that equate to having your head up your backside to get a new gas/oil furnace. It's larger than an EV rebate and a much higher % of the total cost so you'd have to have a really good reason to stick with fossil fuels.

What state?

> He's probably ignoring the externalities like the gas leaks on the way to your house

Where I live (Sweden) and come from (the Netherlands) gas leaks tend to get fixed since they are both costly as well as dangerous. Let's assume that this is not a real issue unless you have some data which points out the opposite.

> the power plant being able to have a huge scrubber that reduces emissions

We're not talking about heating a house using coal - which is where those scrubbers come in - but with gas. Gas fired power plants do not need scrubbers since they do not produce fly ash or sulphurous oxides, nor do gas-fired heaters.

Total systems efficiency for a single-cycle gas-fired power plant lies between 32% to 38% for simple cycle gas turbines, most of those in the USA are closer to the first number. Combined cycle gas/steam turbines can run at up to 60% total efficiency which is about as high as it is possible to get using a thermal power generator [1]. The efficiency of gas-fired heaters lies somewhere between 70% and 95% or more, the upper range is common here in Europe. A good indicator for the efficiency is the fact that these appliances often use plastic flue pipes which is made possible by the fact that flue gas temperatures lie below 70°C. The effective COP for air/air heat pumps is highly dependent on the temperature difference between the hot and cold side, the colder it is outside the lower the efficiency. I don't know where the original poster lives so it is hard to calculate the expected efficiency. If it is anywhere where the temperature goes down below zero (Celcius) it is more than likely that the salesman was right since the effective COP ends up below 2 - and goes down to 1 or lower around -15°C to -30°C (depending on the model heat pump used, the amount of moisture in the air (moist air condenses and freezes on the evaporator which requires a thaw cycle which markedly lowers the efficiency).

[1] https://www.brighthubengineering.com/power-plants/72369-comp...

> Let's assume that this is not a real issue unless you have some data which points out the opposite.

US-wide estimates are 1.4% and recent studies suggest as high as 9% in tested areas.

https://news.stanford.edu/2022/03/24/methane-leaks-much-wors...

OK, those are production leaks, not transport leaks. I don't know how high production leaks are here in Europe but I assume them to be lower due to stringent rules. There is also quite a bit of natural methane leakage from swamps, wetlands and other similar sources as well as from agriculture. ESA has a satellite which can measure this [1], it shows methane leakage from landfills can also be quite large [2].

[1] https://www.esa.int/Applications/Observing_the_Earth/Coperni...

[2] https://www.esa.int/Applications/Observing_the_Earth/Satelli...

All those leaks contribute to the externalities of natural gas. I don't know the relative contributions between extraction and distribution, but leaks in the distribution network are also a problem in Europe [1]. It's certainly true that extraction leaks can be so substantial as to make shale gas worse than coal [2] (twice worse over 20 years!).

Landfills (and agriculture) are big sources of methane. I think this is a pretty good start to figure out what the EU is doing to reduce all sources [3].

[1] https://www.uu.nl/en/publication/scientists-discover-more-me... [2] https://link.springer.com/article/10.1007/s10584-011-0061-5 [3] https://www.consilium.europa.eu/en/press/press-releases/2022...

The USEPA claims about 1.4-2.3% of natural gas is lost to leaks [0].

American is full of leaky gas pipelines. It's one of the major reasons people oppose to large gas pipelines going near where they live: they are an ecological disaster waiting to happen.

[0] https://www.pbs.org/newshour/science/the-u-s-natural-gas-ind...

That is the pipeline... that is not the thing that goes to your house lol. Not to mention that a couple percent doesn't even come close to changing the math given above

> you'd have to have a really good reason to stick with fossil fuels

In Seattle, people lost power during a snow storm for days. As much as I hate burning fossil fuels, what are my options if the power company takes 3+ days to bring back power during 32ºF below temperatures?

My home has a fireplace, but that only heats the living room.

I don't think I've ever lived in a house with fossil fuel heat that worked without electricity. Hot water, sure, but not heat. Typically the thermostat itself is at least partly electrical and beyond that you need electricity to power the blower motor for forced air or a circulation pump for hot water heat.

Not exactly fossil fuel heat, but recently I was staying at a place that had a wood burning furnace which is explicitly designed to work even if the power goes out. The hot air naturally rises and pressurizes the vents slightly, and the only constraint is you have to set the damper in a way that keeps the fire small/cool.

I don't think it would be possible with natural gas or anything like that, as you really do need a thermostat...I assume a continuous burn without the blower is not something they're designed for.

All modern furnaces and boilers need electricity too. The only advantage that they have is that it's a bit more possible to run them for a while on battery backup, but for three days you need a generator.

that's why most of those "whole house" generators take natural gas.

what's interesting is that when looking at solar recently, it turns out that solar generates LOTS more power when it's cold out. obviously when panels are not covered by snow. Actually snow on the ground could reflect more light to the panels too.

Solar panels do a great job of absorbing sunlight and heating up. Combine that with a smooth glass surface and panels will clear themselves surprisingly quickly if they are exposed to sunlight at all.

The gas lines are gonna leak whether you use them or not.

The methane itself leaks out of the ground...

Not to mention the Carnot efficiency losses causing ~50-70% of the heat energy at the generator to go out its cooling system.

Yes, It's not clear at all that heat pumps are always a win -- depending on the energy source mix of your local grid. But with a COP of 3-4 (i.e. 3-4 times more heat is moved by the pump than is supplied as electrical energy) if there's a decent renewable contribution to electrical generation on your local grid, it might well be a win in terms of CO2 emissions. YMMV.

> Yes, It's not clear at all that heat pumps are always a win -- depending on the energy source mix of your local grid

As others have noted, a new gas furnace might break even right now with an electric air-source heat pump, but how is it going to work out as electrification and decarbonization proceeds? Break even now, come out ahead in the future - choose heat pumps.

The salesman could very well be correct. The reality is the numbers are incredibly contextual relative to specifically where you live.

A great example of this exercise was Harry Metcalfe actually doing the digging and the math to attempt to objectively measure his impact, and whether an EV or PHEV made sense as a daily given where he specifically lives in the UK is primarily powered by coal: https://youtu.be/k15n6QAe8cE

For him, right now, PHEV was lower impact, but he makes it clear that that will very likely change over time, and that if he lived elsewhere, he likely would’ve went EV.

- - - - -

This is a classic example of, “it depends.” If you live in an era with lots of sustainable energy, it’s likely a no brainer, but the math changes if you lived in an area powered by a lot of natural gas, or around Appalachia which is still predominantly coal. To answer the question, you have to get the information and do the math to understand what decision you want to make, given your requirements and goals.

- - - - -

For the record, Harry’s Garage (and Harry’s Farm) is a gem of YouTube’s car community. He doesn’t need it to make money, so he just does what he wants and goes down a lot of very nerdy rabbit holes (including sustainable energy, gov’t farm and energy policies), and actually USES his cars for REAL trips — like taking his Testarossa through the Sahara, etc. Harry was basically an “eccentric super car owner” in the 80s/90s (and ghost wrote articles in UK car mags for a while as an “anonymous/eccentric super car owner”) that ultimately founded EVO Magazine, helped influence a lot of the cinematic direction for the Top Gear reboot in the early 2000s, and was the inspiration for “Clarkson’s Farm.”

He’s a nerd’s nerd, and an absolute treasure.

He’s also wrong, or at least wrong for anyone considering the question now.

The UK is phasing out coal completely in the next few years and aggressively pursuing renewables.

https://en.m.wikipedia.org/wiki/List_of_active_coal-fired_po...

Yep, the youtube video at 21:25 contains a screenshot of UK electricity generation mix over a 4 week period in 2020, which was 0.3% coal.

Coincidentally, one of the UK's remaining three coal plants, West Burton A, apparently ceases operation today (31st March 2023).

https://www.bbc.com/news/uk-england-nottinghamshire-65127874...

And of the last remaining two, one closes this year and one next year:

https://en.wikipedia.org/wiki/List_of_active_coal-fired_powe...

So digging in, the issue is I misspoke here, and I may also have not linked to the correct video. It had nothing to do with coal.

Instead I believe it was the proportion of CO2 emissions for the area he's in, relative to other parts of England. Harry is in "South East" England, around Oxfordshire, which from what I can find for around that timeframe.(https://assets.publishing.service.gov.uk/government/uploads/...), is the highest CO2 emissions for any region of England, of around 12%. Continuing to Google, this seems to be fairly consistent in that aside from Scotland, at least around the timeframe of the video (2020-2021), South East England had very high CO2 emissions in general, and I believe the government supplied pamphlet he had in one video also showed how much higher it was relative to the rest of England.

It has since fallen substantially, but even though I linked to the wrong source (and can't be damned to go find the video where he does nothing but crunch the numbers), the point was more that at the time he made the consideration, his decision was swayed because at the time the emissions for where he lived was high enough that it swayed his purchasing decision at the moment. The rationale being that the tailpipe emissions when it had to run the ICE was lower enough than the grid source emissions to where it was slightly cleaner. In fact, it was part of a decision quite some time ago (well before 2020, I believe) to install a 15kW wind turbine on his farm to not just save money, but to ensure it was cleaner power than what was being supplied.

The math of heating is different from turning a motor though.

All energy use ultimately becomes heat. You can burn it directly, then 1J of fuel becomes 1J of heat. Or you can turn it to electricity and use that to locally decrease entropy.

If you mine bitcoin with the electricity, then 1J of fuel becomes 0.5J (approximately, of course) of waste heat in the power plant and 0.5J of waste heat in your GPU.

If you use the electricity in a heat pump, then then 1J of fuel becomes 0.5J of waste heat in the power plant, 0.5J of heating in your house. AND 1.5J of heat is moved from air outside.

Salespeople are often ignorant af.

I have both a heat pump and a gas furnace.

I program my thermostat with:

- Electric cost per kWh

- Gas cost per therm

- Heat pump afue

- Furnace efficiency

It does the math and runs whichever is cheaper.

This past winter, the heat pump was cheaper down to 5 degrees Fahrenheit.

>Salespeople are often ignorant af.

Or so much worse; they learned something for one specific situation/time and now apply it to everything because they don't realize that's not how it works.

Sounds like this one might at least be aware of the complexities and nuance of the situation though.

> I program my thermostat with: ...

What thermostat let's you input all these data points?

Trane xl1050.

Requires getting into technician config mode, which I’m pretty sure could result in rendering it inoperable if I screwed with the wrong settings.

But it’s doable; I go through the process whenever my utility company changes their rates.

He's kinda wrong unless you live in the northern part of the country.

A heat pump is a multiplyer - it takes that incoming energy and can get a multiple of heat (the exact multiple is the rating of the pump and varies).

That's where the part of the country comes in - in the north the multiplyer is lower, in the south it's higher. With a nice high multiplyer it's a great deal.

I wish though, that they had natural gas based heat pump - now THOSE would be really efficient!

You can buy propane-fired refrigerators so I do not see why you couldn't make such a thing. You can also buy heat pumps where propane is the working fluid, which is vaguely ironic.

Natural gas powered heat pumps actually exist, and are commercially available, although rare in North America. Most use an ammonia absorption cycle. Efficiency is lower than one might be hoping, quite a bit less than 2x. Here's a Canadian study evaluating one: https://sustainabletechnologies.ca/home/heating-and-cooling/....

That can't be right. Heat pumps are commonly 2.5x-4x more efficient than direct heating.

"The U.S. Energy Information Administration (EIA) estimates that annual electricity transmission and distribution (T&D) losses averaged about 5% of the electricity transmitted and distributed in the United States in 2017 through 2021."

https://www.eia.gov/tools/faqs/faq.php?id=105&t=3

I downvoted you for your overconfidence. Your conclusion might be right, but it's not as straightforward as you suggest. You're right that the transmission losses aren't large, but you seem to be missing the much bigger losses involved in generating electricity from coal.

Currently, the average coal fired plant produces electricity at 33% efficiency: https://www.energy.gov/fecm/transformative-power-systems. That's average, so there are probably plants out there producing at 30%. If we assume another 5% loss for transmission, this takes us down to 25% efficiency as delivered to the consumer.

If a heat pump is 3x the efficiency of resistance electric heat, but you are burning 4x the coal to generate the electricity, are you still certain that a 95% natural gas furnace is never the better choice for efficiency? I'm not. I think the heat pump is probably more efficient in many cases, but I wouldn't eliminate the possibility that there are cases where the natural gas wins.

This is definitely the the worst case, but in how many places is coal the only thing on the grid? If I look a bit randomly at electricity maps there's barely any place left where it's just coal on the grid.

The problem is in the future when you decarbonize how are you going to do it with a gas furnace? Bio-gas is extremely niche and shows no sign of picking up anytime soon. Meanwhile your local power plant already switched from coal to natural gas, but in the future the grid is going towards wind, solar, and battery storage.

You can even install solar panels locally to cut down on transmission losses.

As someone who has owned or rented homes heated with oil, gas and heat pumps (the latter two in the SE US), my experience has been that the gas and heat pump systems cost about the same same to operate. But when the gas system in our current house had to be replaced about 5 years ago, I went the path of least resistence and got the recommended gas unit. I really regret that decision now, especially given the small difference in installed price. Same with the tankless water heater (although there, gas was all that was available on short notice). The momentum in favor of gas is still enormous, and at least around here strongly influences what installers recommend. Maybe better educated consumers will change that. Unfortunately, I'm going to be stuck with gas into the next decade, with the only consolation being that at least I'm done with oil (the last two oil burners I ran were from the 50s, for steam heat, and cost a fortune to run: one winter in the early 00s about $600 a month).

Why the focus on coal? California as a whole only sourced 3% of its energy from coal in 2021, and some regions were at 0%. It only made up 20% of the entire US' consumption in 2022

https://www.eia.gov/tools/faqs/faq.php?id=427&t=3

I used coal because the GP said they were in an area where coal and natural gas were primarily used for generation. Since coal is used as part of the blend, it seemed reasonable to consider it as a worst case scenario for efficiency. I wasn't objecting to the general conclusion, just the implication that there was clearly no case where natural gas heat might beat a heat pump.

I'd happily concede that in all locations in California a heat pump will be more efficient when averaged over the entire year. I'm less sure about Winnipeg or Whitehorse, especially if we are looking at shorter timescales. Did jmchphers indicate somewhere that he was in California, or even the US? If he's somewhere very cold, I think we still need to at least run the numbers.

(I should probably also add that I've got a heat pump hot water heater and heat pump dryer. I'm a big fan of the technology---I just don't think it's always the head-and-shoulders winner for all people in all locations at all times.)

Power is like real estate. Location. Location. Location. Where I live all/most electricity is generated from hydroelectric. I feel like everyone commenting should post where they live or how their electricity is generated.

Sorry to have been unclear - my comment was a response to this specific claim, which only considers power generation via natural gas, not the grid as a whole, nor coal:

"Due to transmission losses, it is cheaper, efficient, and greener to combust natural gas for warmth directly than to burn it at a power plant, feed the power into the grid, and use grid power to run a heat pump."

This statement does leave itself some wiggle room with "cheaper", but in terms of "efficient" it cannot really be true, because the average efficiency of a natural gas power plant is 45% - and if I'm reading this document correctly, that figure already factors in transmission loss:

https://www.eia.gov/todayinenergy/detail.php?id=44436

Good points, but in case anyone is still reading, I feel compelled to stick to my guns: I think it matters where you are. Figures 7 and 8 in this 2022 paper from Lawrence Berkeley Lab give maps of the seasonal minimum heat pump COPs necessary to achieve cost and CO2e equivalence with a 95% efficiency gas furnace: https://escholarship.org/content/qt8pt9155c/qt8pt9155c.pdf.

It requires making some assumptions about heating season air temperatures, but I think it shows that with current electricity generation there are several states where air source heat pumps are actually worse for emissions. And that at current energy prices, there are several states (not necessarily the same) where they are not a win for running costs. Betting on the future "greening of the grid" is a good argument, but the timescale matters. I like the future of heatpumps, but I worry about a backlash if the benefits are oversold.

I appreciate your attention to accuracy in this discussion. I think we are basically arguing against different oversimplifications, not really disagreeing about anything fundamental.

My own house was built with hydronic floor heating, via natural gas. We added a ductless heat pump a few years ago, but we primarily use it for cooling. It would be a clear win from an environmental perspective, since our utility is 80% hydro and 0% coal/oil/gas; but the radiant floors are so much more comfortable that we haven't made much use of electric heating yet. We'll probably have the heat pump upgraded in a year or two, to cover more of the house; perhaps that'll be a good moment to shift our habits and see how it works out.

They aren't real common, but there do exist air-to-water heat pumps that can be used for radiant floors. They usually aren't hot enough for pre-existing baseboard, but hydronic flooring runs cooler. Not sure about availability, but here are some specs from a Canadian manufacturer: https://www.arcticheatpumps.com/specifications.html.

The combustion efficiency of the fossil fuel electric generation must also be considered. If that’s 40% efficient, a heat pump with a CoP of 2.5 is very close to a 95% AFUE gas-burning unit.

Combined cycle gas power plants are about 60% efficient. Coal power plants are around 40%, but even the dirtiest parts of Florida aren't all coal (https://app.electricitymaps.com/map)

But of course this is short-sighted, because the grid is greener in most places, and will get even greener over the lifetime of the heat pump, while the gas furnace won't get any better.

Doesn't sound like this person is educated in thermodynamics. Which is why the law needs to step in and just outlaw or tax mineral gas appliances. Letting some petro-poisoned goof talk citizens out of buying electric heat pumps is suboptimal.

Keep in mind that gas infrastructure is leaky, which means that between two to seven percent of the gas that is pumped to your home is lost to the atmosphere before it arrives (depending on the age and maintenance status of the gas pipes in your area). Methane is a very potent greenhouse gas, and this leakage can easily tip the scales back in favor of heat pumps, even with electric transmission losses.

But does it leak in a dose-dependent way?

Is there a marginal increase in leakage if you pick a gas furnace over an electric heat pump?

> Anyone have any numbers to back this up or refute it?

Don't know where you are, but here in the UK right now the split is 34% wind, 29% gas, remaining <other> [0]. If you migrated from a modern condensing boiler with 90% efficiency to a heat pump with 300% efficiency (1 unit of electricity outputs 3 units of heat), then with the gas condensing boiler you're getting 0.9 units of heat per unit of gas, and with a heat pump you're getting 0.87 units of heat per unit of gas, _plus_ 1 unit of heat from wind.

Over the last year, the _majority_ of the time the split in generation sources looks like this. It's occasionly heavier on gas, but for 11 months of the year, it's a no brainer, and I don't think that outdoes the 1-2 weeks per year that you're using an almost equivalent amount of gas.

[0] https://grid.iamkate.com/

Whether or not that's true for your particular situation is going to be very location dependent, but I think the salesperson is fairly wrong in the general case in the US. Fossil fuel generation accounts for about 60% of US electricity and natural gas electricity generation is around 50% efficient. Another 5-10% is lost due to transmission, so say around 40% of the energy potential of a natural gas power plant makes its way to your house as electricity. Combine those and it means that every 1Wh of electrical energy generated takes the equivalent of 1.5Wh worth of natural gas.

That doesn't sound particularly good, since new natural gas furnaces can be around 90% efficient, meaning that same 1.5Wh of natural gas could produce 1.35Wh worth of heating. Except heat pumps have an efficiency of around 2.5-3, meaning for every 1Wh of electrical energy they consume, they produce 2.5-3Wh worth of heat. That means producing 3Wh worth of heat with a heat pump consumes 1.5Wh worth of natural gas in the standard US electrical energy mix. Getting that same 3Wh worth of heat directly from a natural gas furnace would take over twice the amount of natural gas. Even if your electricity generation is 100% natural gas, the heat pump would be very competitive with natural gas.

Now if you live in an area that gets really cold (meaning heat pump efficiency on average is lower) and all your electricity is generated by an old coal power plant (which is less efficient and dirtier), natural gas heating may actually be a greener option for now. But on average that's not the case and many places in the US have much better green fundamentals for heat pumps thanks to mild temperatures and/or lots of non-fossil fuel energy generation.

> natural gas electricity generation is around 50% efficient

The real number is far lower for the majority of power plants using simple/single-cycle turbines which end up somewhere between 32% and 38% [1]. Combined-cycle can go up to 60%, CHP (heat and power) can be up to 80% efficient.

[1] https://www.brighthubengineering.com/power-plants/72369-comp...

>so say around 40% of the energy potential of a natural gas power plant makes its way to your house as electricity. Combine those and it means that every 1Wh of electrical energy generated takes the equivalent of 1.5Wh worth of natural gas.

If the efficiency is 40% it means 1Wh of gas energy produces 0.4Wh of electricity, does not it? How is it possible then to get 1Wh of electricity using just 1.5Wh worth of gas? 1Wh = 2.5*(0.4Wh).

Heat pump with gas auxiliary heat for cold nights. That's what we run and it is the best of both worlds.

I tried to get a quote on a heat pump here (Ontario, Canada) last week because the gov't has incentives up to $5000 on them right now. My gas furnace doesn't need replacing (9 years old) but the AC does. So I figured I'd ask them to quote on a hybrid configuration in a way where the furnace could maybe be swapped out later when it hit EOL, and in the meantime just be used for very cold temps.

Problems:

Gov't incentive only applies to a full replacement, existing gas furnace would have to be ripped out. Seemed wasteful.

High pressure sales guy wouldn't give me a straight answer on pricing, or even proper spec sheets, but sounded easily like $25,000 CAD would be about the price for a system. And that was on a "medium range" system. That's gotta be at least 2 times more than a new gas furnace + AC. Maybe 3x.

I'm on a rural property, and have the space to do excavation for ground source heatpump, which I suspect would get me an even more efficient system. Sales guy was clueless about them, but it also seems like nobody around here really does them.. still? (My parents have such a system in Alberta, for over 10 years)

Also kind of suspect that gov't incentives just get turned into price increases by the suppliers.

Unfortunately just very frustrating. I'd love to do the right thing here, but it seems at this point that pricing still favours natural gas heating. At least for renovations/replacements? Guess I'll wait for the furnace to die.

I don't know if anyone else is following this as an issue, and maybe in the grand scheme of our housing "demographics" it's a small thing.

But if you live in a medium or large sized condo or apartment building, it is extremely hard to get legacy systems like gas furnaces or hot water boilers replaced by a new technology like this.

Not because of lack of desire, but because it involves incredible amounts of:

-- legal questions on whether you're allowed to do such things as an entity (will the owners agree to do it)

-- who will pay for the new costs of the thing itself, as well as the ongoing maintenance, any changes to insurance costs, etc. (how will current people who have to pay shoulder the costs of future benefits)

-- (sometimes) how to divide up or give up space from existing ownership stakes to fit the new hardware into what was never expected to be modified in the building ever again

-- electrical, plumbing, power, heat, requirements that may change the performance or costs of your building (how will you swap a 300 pound furnace with 1200 pounds of condenser units and not have the roof collapse?) Technical feasibility not matching the policy goals.

And then on top of this all, the local city wants their say to block or make it very expensive for you to do all this. (yet at the same time their city councils are charging forward in requiring the phase out of natural gas while not fully understanding the inability or cost to real people of not having the ability to affordably implement those mandates)

For some kinds of buildings, this is a very big problem stopping people from being able to change things. There needs to be some enabling legislation to cut out these roadblocks, or somehow make things easier.

Contractors know this so well they apply probably a 10x discount factor in the number of calls they receive to the number of projects that actually proceed to being started.

Single family / single owner homes have a much easier time just getting it done. And new build.

It can be really very difficult to displace existing technology, for very real and legitimate reasons.

Heat pumps have the same footprint as, and can replace, AC condensers. So if you already have central air, you should be able to retrofit a heat pump. You might need a new air handler, however.

Yes, that's true. I was just focused on another case of for example, trying to turn a large building's hot water boiler into an electrical / heat pump one. That is where the set of huge new condensers comes in, replacing like 1 previously dishwasher sized boiler.

If you don't already have central AC, you likely use window units. Mini-splits can be good in these situations. They can be mounted on the exterior wall and the heat pump can be mounted in many different places.

Never mind being a renter. There isn’t much incentive for landlords to previous feeding cost for their tenants.

My previous apartment was built in the 80s and used only electric resistive hot water heating in an apartment with quite literally gaps in the windows and outside door sealing, in a climate that is below freezing for at least a month of every year.

That shit should be considered criminal. But noooooo landlords provide so much value! Think of the poor struggling landlords! The landlord is a company in boston running hundreds of the units in this city, across multiple companies.

It is the well-known "split incentive". The only solution is regulatory. A governmental agency needs to step in to either mandate the efficiency investments or require that the landlord pays the energy costs.

http://cbei.psu.edu/split-incentives-and-green-leases/

Agreed. Where I live, the government has a very progressive approach on climate change. There is a large carbon tax. Home owners can get a large credit to retrofit their home with a heat pump. Yet in this market, there is a shortage of rental housing, so landlords have little incentive to renovate in any way, let alone to reduce heating costs for tenants.

Like Boston, renters suffer with leaky windows and exorbitant heating bills while home owners tap climate change refit incentives and reap the considerable rewards. Need I also remind everyone that, during the pandemic, almost no home owner had to pay their mortgage, whereas there was no such abatement for renters.

> Need I also remind everyone that, during the pandemic, almost no home owner had to pay their mortgage

This is patently untrue

Contrast this to cities like NYC that are explicitly phasing out gas infrastructure. New buildings will be banned from installing gas hookups in units and will require electric stoves (induction or otherwise). They haven't banned gas for central heating but the incentives may start to nudge that direction.

NYC has not thought this through.

You still need gas for heat and for hot water. NYC is cold, heat pump versions of those work, but not very well (especially not well for hot water).

And for apartment centralized heat and hot water? That would be really hard - these units are much later than the centralized ones they replace.

The amount of electricity it would take to do this though.... I hope they plan for this to take decades, because that's what it would take for them to upgrade their wires.

80% of buildings in NYC are heated by steam, not gas, generated by a boiler in the basement. I assume most of those boilers are themselves gas-burning, but I also assume that any refit to these buildings would just replace the gas-powered boiler with an electric one. When it comes to boiling water, induction stoves are already more efficient than gas stoves, so it doesn't seem infeasible.

My NYC co-op is going through this now. All of your guesses are basically right. We're having separate systems installed for replacing in-unit hot water and in-unit heating and cooling. I believe the new electric hot water system is being installed in the basement and the condensers for the in-unit control panels are being installed on the roof and routed through the pipes used by our old radiator system.

Pros: units can control their own heat and will no longer need in-window A/C units. Cons: it's really expensive, even for a building with good finances and access to reasonable financing options.

We're only doing this because our boiler is probably a few years away from failing already (it's well over 50 years old), and we're super close to the building size threshold where we would be fined for not complying with the law (so any adjustments to how they calculate building size or dropping the law's fine floor would certainly push us over).

> would just replace the gas-powered boiler with an electric one

With resistive heat? That would be a horrible idea.

And creating steam with a heat pump would be less efficient than gas.

So like I said, they have not thought it through.

Induction... Look it up.

You realize induction is still resistive heat right? It's just directly resistive in the magnetic metal, usually an iron pan on the stove.

That's not what the grandparent comment meant, if they're complaining about efficiency.

Some other comment mentioned induction, but that doesn't make sense in the context of heating a house.

Your parent comment said resistive heating is terrible for heating houses, which it is.

You replied Induction... Look it up. Induction is still resistive heating and doesn't create more heat for the same electricity, so what are you talking about?

The entire discussion is about boilers and steam...

This entire subthread is useless when you missed the original comment: https://news.ycombinator.com/item?id=35393157

I already mentioned that comment when I said one mentioned inductive heating.

What is it that you are trying to say? Inductive heating has no benefit over regular resistive electrical heating for heating a house, because it is already resistive heating. For a stove it just transfers the resistive heating to the pan directly instead of using an iron coil burner first.

All you did was make a sarcastic comment but there is no context where it makes sense and it's even more bizarre that you think other comments help it make sense.

NYC has only banned stoves thus far and only for new construction. Also NYC isn't that cold. We had nearly zero snow this winter. Doing nothing isn't an option right now.

A city-scale ocean-source heat-sink system might be interesting in New York.

I'm in the UK, and got an air-to-air heat pump (more commonly known as air conditioning). It made sense because of extremely high electricity prices, and I have an insulated house without gas, electric only. There's a lot of houses / flats similar to mine, that could switch from resistive to heat pump heating. Unfortunately, the government are focusing on very expensive retrofitting of air-to-water heat pumps in older uninsulated houses, which doesn't make a lot of sense.

I was not aware until recently that most air conditionings can produce heat really efficiently. For hot water, efficiency is quite low, so using a simple air conditioning for room heating combined with an electric boiler for shower water would achieve a lot at quite reasonable price.

It's air to air, so it's for heating air only. I still use resistive heating for hot water.

I tried to get a heat pump but asinine local regs require five full feet of setback from property line to the edge of the external condenser. I'm not willing to spend $15k upgrading my connection just to get electric resistive heat, so I had to get a new gas furnace instead.

Also, why are heat pumps so hideously expensive? I was quoted $35k, not including the electrical upgrades. A plain AC is half that but it's virtually the same mechanical equipment.

That price is ridiculous. I just had a combo high efficiency 4 ton heat pump with backup natural gas furnace in an Illinois property for $17k.

Unless your house is ridiculously large I think you were given a sky high quote because the contractor didn't want to the job. I paid less that half of that for a full ground source geo heat system a few years ago.

Heat pumps are typically more complicated to install and size properly. You can throw an oversized gas furnace in any house for fat profits and no real HVAC design.

Contractors that aren't wanting for business can give you ludacris estimates for jobs they're not interested in. If you take it, great, they make a lot of money, if not they can schedule someone else or push you into an easier job for them.

I ran into this with a concrete job I needed done recently. The contractors were all booked a year or more out, and were quoting $20k+ for a normal concrete driveway. I found a paver installer who seemed much less busy, was able to do a full paver job for way under the slab pourers!

I’ve got several quotes over the years and afaict it’s just like this in California now. It’s maddening.

> ludacris estimates

Ludicrous :-)))

Did you get multiple quotes? The "premium" contractors will commonly quote something sky high, but if you get another quote they'll commonly price match. I negotiated a HP install from a preferred contractor from $18k down to $9k with a price match earlier this year.

I wonder if a dual-fuel system can optimize the use of heat-pumps and gas heating. Could a control system also use the current price of each fuel to determine the mixture.

https://www.goodmanmfg.com/resources/hvac-learning-center/hv...

In 2008 I moved into my first apartment with a proper air-to-water heat pump. Granted, the place clearly also had a smart architect, and was built to very high efficiency standards (was rated LEED Platinum). It was installed in a small void between a living room and the bedroom, adjoining an exterior wall. Had an access panel. You’d only barely hear it initially start up. Because of its location, the total length of the ventilation ducting was maybe 1.5m, so air didn’t really change temp before it was delivered to its destination.

Nowadays I rent a floor in an old Victorian home converted into a duplex, still running a boiler (single loop for both floors) going to radiators and convectors. Real noise from the basement from the pump, banging of pipes, and the air quality monitors clearly show VOCs rising — sometimes to really crazy levels (250+, sometimes 400-600!) if upstairs cranked the heat to hell and back.

Where I live now has mediocre insulation at best, and an uninsulated three-seasons room on the 2nd floor that might as well just be open to the outside air. In 2017 when I left, my electric bill was only about $45/mo (1BR, all electric appliances, though elec was half the price back then), and that included in-line water heating (with 3gal tanks for the bath and kitchen). Meanwhile, my landlord currently pays about $7000/year in fuel oil to heat this duplex and its water.

Granted, it’s far from an apples-to-apples comparison as where I lived for ~9 years was ultra-modern construction with no corners cut, and I didn’t share heat/hot water with neighbors that have a far more demanding “standard of comfort”. If only I lived here, might only be $2000/year since my standard of comfort is a lot lower than upstairs, but it really shows the difference that construction, insulation, maintenance, HVAC system choices, and just lowering your standards a bit makes.

House across the street just sold. Had vents and forced air, but still a boiler. New residents haven’t moved in yet, but they IMMEDIATELY removed a fairly new boiler, plus the 375 gallon fuel tank. Putting in a heat pumps and a hybrid water heater. Don’t blame them for both the long-term savings, plus reclaiming floor space in the basement.

Yes, the question of furnace vs. heat pump should always be deferred until after your insulation is up to snuff.

Something that readers may not know is that they are now heat pumps on hot water heaters. An added benefit is that the fan on the heat pump will exhaust cold air. That might be a benefit for some folks!

Can you clarify what you mean? There's only ~2 fans in my system, the one on the heat pump outside (looks like an AC unit) and the one in the air handler in the basement. To me sitting in my dining room this system is no different than any other forced air system.

The air for a hot water heat pump could be entirely indoor air, the entire unit is located inside.

Unlike an A/C which is split, with the compressor located outside.

He's saying that instead of a gas or electric hot water heater - you can now buy a heatpump version. It works the same as a normal heat pump, but it takes ambient air in your basement or garage or wherever, and then moves that heat into the water which provides a slight cooling and dehumidifying effect for your indoor climate. They make a lot of sense in the US South.

https://www.energy.gov/energysaver/heat-pump-water-heaters

To be precise the heat pump water heaters are electric - they just use latent heat in the air around them as much as they can, but they'll fall back to electric when that isn't enough.

They also cease working when the power is off, of course.

They exist, but are really only good in the southern part of the US.

In the north the incoming water is cold which really slows down the hot water creation (recovery) rate, and that cold exhaust then needs to be warmed up by the heat.

If you have low usage (i.e. less than 40 gallon/day of hot water) you could get away with it, but that's two showers - so if your usage is more than 2 showers per day I would avoid them.

But in the south they are a much better choice, since the recovery rate is much better and the cold air helps with A/C.

I have (air source) heat pump water heaters in two different basements. (Don't ask.)

A big win for me is that I no longer need to run a dehumidifier in those basements. The cold air output from a water heater alone is good enough to keep the humidity down. Again, YMMV.

There are also heat pump dryers. Requires no exhaust ducts, reduced energy consumption but longer drying time.

My unit has both a heat pump and gas furnace. Of course the heat pump is used for cooling in the summer. In the winter the thermostat is set to use the heat pump for heating until it is below 40F. Below that and it switches to natural gas. The company that installed it and maintains it said that was the best crossover point for efficiency and cost. I didn't look at any specific cold weather heat pumps that are still efficient below freezing.

All heat pumps are generally still efficient at well below freezing, and will have a COP (efficiency) above 1 even at -15C. The problem is that they don't generate a huge amount of heat at those ambient temperatures, so you need a backup source of heat. A heat pump should be able to keep your house at room temperature when the outside temp is around freezing, but it will take a long time to heat up your house if you let the temperature drop overnight.

40F seems unusually high for your aux heat set point, unless you have expensive electricity and cheap gas.

I wish the mini DIY heat pump was more widely adopted by manufacturers! Mitsubishi and Mrcool make split systems that do not require installers. Having to hire trades to gas them etc is such a pain - small rooms, once you add up the unit and install cost, you may as well just buy a $60 heater off Amazon and swallow the poor efficiency.

With American electric prices maybe but here in NZ the installation pays for itself quickly.

Can someone please speak about their experience with the cost of running a heat pump for the same amount of time as a gas furnace or AC?

I’m still confused about why a heat pump is so much more efficient, since the only change from a typical AC and compressor setup is the two-way valve that allows the system to reverse and a different refrigerant. Would it still not use the same power hungry compressors as before? I always thought the most expensive part of running an AC was the compressor.

In terms of Gas, does it actually run cheaper than the per-therm Gas costs?

It's not that it's more energy efficient than AC per se, just that running it in reverse to move heat into your house is much more energy efficient than using electricity to generate heat compared to electric resistance heat.

Relative to gas, it's going to be competitive when the ambient outdoor temperature is > 40 degree Fahrenheit, but probably more expensive depending on utility rates where you live.

If I rephrase what you said to make sure I understand it correctly: Cooling costs would be the same as AC units and heating would be cheaper or same depending on the cost of Gas. Would that be correct?

Generally. Depends a bit on climate, choice of heat pump, and relative energy costs.

A ground loop can make cooling cheaper too, as can upgrading to newer more efficient compressors.

Thank you! Also sounds like heat pumps come with multi or infinite stages akin to a CVT to be able to run at any speed for the heating or cooling demands. Rather than legacy units that are only On or Off.

Down in the comments, sounds like MA has good incentives, but not seeing other states. CA is banning new gas installations, so I assume heat pumps are the only way for new developments

> Also sounds like heat pumps come with multi or infinite stages akin to a CVT to be able to run at any speed for the heating or cooling demands. Rather than legacy units that are only On or Off.

Yeah, kinda. They can convert the incoming power to dc then back to ac at a different frequency so they can run at any speed. This cuts the energy losses from start-stop.

Less related to heat: It also has a neat side effect that it's a very simple change to make them run directly on solar with no (separate) inverter (and with no AC->DC step). On top of being more efficient even with AC->DC->AC this means in hot climates the energy used for cooling is used more efficiently, and the inverter on the solar array doesn't need to be as big (if you're getting full noon sunlight you probably want the AC on).

I don't believe there is a municipality anywhere in the US where heat pump heating will be cheaper than nat gas on run rate basis.

I actually used https://www.ncei.noaa.gov/products/land-based-station/us-cli... for my city to develop a model for the cost of btus from either method throughout the year and the heat pumps cope at that hourly temperature, and it was slightly cheaper for heat pump for the entire year. But I also live in a marine influenced climate in the west with low electricity rates.

Whereabouts did that actually work? I can't think of a west coast locale where electricity is actually cheap and you get anything remotely resembling a winter.

I can see places like coastal california where you're on AC virtually year around and maybe need a day or two of heat.

> I can't think of a west coast locale where electricity is actually cheap and you get anything remotely resembling a winter.

Eastern Washington? 10 cents kWH in Spokane.

I don’t know if any coastal Californian locale that needs AC for more than one or two weeks a year. Even in LA you can get by without AC.

Yes! It could be more expensive too, the real kicker is utility costs and how cold your climate gets.

I don't have direct comparative cost experience, but the reason heat pumps are so efficient is that while they do indeed have to run a fairly energy intensive compressor, that compressor allows them to get heat energy for free from the outside. By using the compressor to make the outside refrigerant very cold, it absorbs heat from the outside air (for air source heat pumps) even if it's cold outside. That absorbed heat energy required expending energy to run the compressor, but it ends up allowing the system to absorb several times more heat energy from the outside air. This marginally cools down the outside air, but that gets heated back up again by the sun. Arguably making heat pumps solar powered.

New York here, heating via heat pump is about 5x as expensive compared to natural gas. Paid around 100 bucks in gas for 1700sq ft place with 18foot ceilings, where as our power bills are north of 400-500 for 1400 sq ft heat pump set up.

We have a new Daikin inverter heat pump set up in the 1400sq ft place and are actually retrofitting a nat gas solution - when it was 20F it took a full 24 hours to get our place from 55F to 70F because the pump stops for 15mins at a time to defrost.

Greenwash aside, I would not recommend the heat pump solution anywhere north of Atlanta unless you're doing underground coil + nat gas backup.

Also heat pumps are evidently terrible at humidity control - even in the "dry" mode our place would shoot up to like 70%+ RH, ended up getting whole house dehumidifier to handle this.

If only someone made a good thermostat for them. Nest and Ecobee integration doesn't work very well since they need to go through a two-stage controller interface.

I am using an Ecobee thermostat with a heat pump and it is working, for both heating and cooling. Is it doing something inefficient or wrong? What am I missing out on?

Edit: Ecobee says they support heat pumps. https://support.ecobee.com/s/articles/What-types-of-HVAC-sys...

Which heat pump do you have? I’m on a Mitsubishi which requires a bridge unit which has its issues.

I use a Nest thermostat with a 2-stage ground sourced heat pump (a.k.a. geothermal) that also has backup resistive heating. It works perfectly fine. It will run a single stage most of the time, or both stages if it's trying to change the temperature by more than a couple of degrees.

I have mine set to treat the resistive heating as emergency backup, but I believe I could also configure it to treat it as a third stage and run it automatically.

I keep reading that, at least for air source heat pumps, it cuts into a lot of the efficiency advantages if it’s cycling a lot. Better to run at a low stage for a long time as opposed to a higher stage on and off.

Maybe I should just try and see what how it works for me though.

Comfortnet works pretty well, and I can control it via an app.

If we could get a mini split installed in every house in the country it would save around 1 trillion dollars of energy costs over the next 20 years. That's just the savings in kwh of electricity, it also means less energy produced, less carbon, less grid capacity needed, less production facilities, etc etc.

Our gas furnace has a few years left then we will be getting one. It's kind of a no-brainer.

Lot of discussion here => Heat pumps of the 1800s are becoming the technology of the future. https://news.ycombinator.com/item?id=34397715

I have been asking about this locally, here in Oregon, and it seems that in the US we're likely to get some financial incentives. But nothing seems sure yet. Anyone here happen to know anything?

There are incentives in the IRA, but (except for ground-source, which is a straight up 30% uncapped tax rebate), they're limited by income and capped to certain dollar amounts.

We have had them here in Massachusetts for a while. $10,000-15,000 rebate depending on what the house requires.

https://www.energytrust.org/residential/incentives/furnace-a...

Some of the incentives may be limited if you have too much income.

I was able to get the latest Ecobee thermostat for $90 instead of the list price of $250.

Fortunately or unfortunately, I started reading about how 3rd party thermostats can't talk to multi-stage furnaces or air handlers except in very blunt increments. Maybe as blunt as on or off. Each manufacturer has their own, undocumented protocol for doing fine adjustments. I tried running the fan all the time (now I do 10 minutes every hour) and it was quite expensive for that month. Anyway, I'm hesitating about putting in the nice Ecobee thermostat because it could conceivably cost quite a bit more in electricity.

Oregon seems like a perfect use-case for heat pumps. It has a lot of renewable energy and relatively mild winter temperatures (at least near the coast where most of the people live), two things that make heat pumps a lot greener of a solution than natural gas heating.

So has any wackadoodle chimed in here yet to claim this is the result of "the woke/radical left" coming to take their God-given gas furnace away, similar to their claims about gas stoves[1]?

[1] https://www.theguardian.com/us-news/2023/jan/11/republicans-...

I think this probably has a lot to do with the general trend to go electric. We used to have gas ranges, gas clothes dryers, I think hvac is no different now that split units and heat pumps are getting better, easier to install and cheaper

Forced air Furnaces cause health issues when the filter isn't changed very often, or there is dust in the ducts. Best form of heating is under floor radiant heating.

Underfloor heating is awesome but it’s also very expensive, particularly if you’re also in a climate that also needs cooling.

How significant is Earth cooling speedup due to heat pumps? Is this practice ecological? (I assume they pump the heat from under ground?)

Some heat pumps use underground pipes (and those units have a great advantage in avoiding the efficiency loss due to extreme temperatures), however they're much more expensive to install, so the vast majority of heat pumps are air-based, same as any traditional air conditioner you've ever used.

As for whether ground-based heat pumps would cool the Earth's crust, the answer is no (in any measurable sense). Consider that heat pumps are used for both heating in winter and cooling in summer, so in a temperate climate you're just as likely to put as much heat into the ground (in summertime) as you extract from the ground (in wintertime).

Thank you

That's an interesting question, whether heating and cooling by humanity are really balanced.

People living in cold climates (northern countries and areas) mostly heat. People in hot climates (Africa, India and such) mostly cool.

All this focus about environmentalism and efficiency lately is making me think that we're not even daring to look at the supply side of this equation. We should have basically infinite energy situation figured out by now. The fact that we haven't and we're squirming about how to automatically turn off my garage lights is an indictment of our failure as a society. Power generation technology is stagnated to the point where fusion is only 4 years away for over 40 years now. Wind and Solar keeps the population delusional as they feel proud to wear insulated clothes indoors. Poor and middle class struggles are ignored. But, the virtue signaling Berkeley folks will surely tell you how their $1.3M 900 sq ft home is heated using heat pumps. I feel extreme dissappointment in our inability to engineer things everytime I see a Nike shoe box with greenwashing labels.

We should aim a lot higher. Like 1000000x higher and solve the problem of energy once in for all. But, something tells me that we will have protests in the year 2200 for engulfing the last 20% of the sun with a dyson sphere. There will be folks trying to campaign for "Leave the sun alone".

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