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Comment by wongarsu | Hacker News Reader

For a long time the main problem of heat pumps was that while they are more efficient, a kilowatthour of gas or oil is much cheaper than a kilowatthour of electricity. But in the last two years natural gas prizes have gone crazy, removing that price disadvantage.

Of course heat pumps emitting no particulates and being able to run on renewables are also good reasons, especially as the health impact of living in cities with high PM2.5 values becomes clearer. But I don't think those are the primary drivers.

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Heat pump technology has also improved significantly. You can now buy heat pumps that remain efficient down to very low temperatures, which makes them appropriate for a larger range of climates now.

Many models are in very high demand. Some of the units I looked at recently were back ordered so far that I was told to pick something else if I expected to have it within the year.

The demand is very high because the technology is good. It’s not a campaign or conspiracy.

Yeah it almost makes the opposite of sense. If manufacturers are already backordered a year in advance why would they still throw money at marketing

The war in Ukraine has resulted in a real push to get off of oil/gas based heating, on top of global warming concerns that have already been doing that.

There are lots of different groups looking to push heat pumps for the above reasons. Governments are concerned about both war and global warming. Ukraine supporters are concerned about Russia getting more money (to wage more war). Green activists are concerned about global warming. All have their own reasons to push heat pumps on everyone.

It's not directly related to the recent spike in prices, especially considering that a heat pump installation is very expensive in itself and potentially disruptive.

Rather, it's a combination wanting to get to net zero, so no emissions, with the big problem of generating enough green electricity. A heat pump system has no emissions and consumes much less electricity than an electric boiler/electric heater.

I replaced my old air-to-air heat pump with a new one last year. Cost me in total around $3000-$4000. Might have been a bit more expensive if it was a completely new install depending on how it would be installed, but not too much more expensive. Might be more expensive in countries where you are using gas boilers as it sounds like your heating setup is much more complex than where I live.

Here in the UK, I think the cost of installing a new heat pump, bearing in mind that it's an installation from scratch, starts at about £10k ($12k as today's rate) to several tens of thousands. A ground source heat pump (which seem to be the ones pushed by the gov?) is probably £15k to £30k if you can install one at all. Replacing an existing gas boiler, which is what most people have, is probably around £2k or even less in simple cases. I had mine replaced 2 years ago with the new one installed on a different floor so a fair amount of plumbing was required, and it 'only' cost me £3k.

There are government subsidies but it's still much more expensive in the end. I think they are simply too expensive and impractical to install for most people.

FWIW, I just installed two heat pumps in a 3100sf house in the US northeast this summer. We already had ducted AC. The main unit was US$17K and the mini-split for the master bedroom was US$6K. There a US$10K state rebate, but we'll probably only get 70% of that because we've retained the old heating system as a backup and for water, so total cost is US$16K. These are cold-climate units, both rated down to -4°F but I haven't actually made them work below 20°F yet. Next year I'll probably set the aux cutover temperature to something lower and see how it goes. Year after that we'll probably install solar (plus wind if the technology for that has moved along far enough) and switch to all-electric everything.

BTW my town has an all-electric mandate for new construction already, and there's a lot of that. There's also a bylaw that takes effect in 2025/2026 banning gas-powered landscaping equipment.

I think prices have spiked. Two years ago I installed a new heat pump to replace an old failing 5-ton air conditioner (which was paired with a high efficiency natural gas furnace; I kept the furnace as backup instead of relying on electric strips). It was $6K altogether. Was just going to replace the A/C with a new one, but the differential was $1500 and so I figured why not.

OTOH, a few months ago my stepmother installed minisplits after getting quoted $22K to install a whole-home forced air heat pump (going from no forced air at all, so part of that cost was ducting, though it's a single story ranch house so not terribly difficult).

Somewhere between those two points, prices went insane.

What heat pump did you get? I wanted to get a heat pump, but I ultimately ended up just buying AC. I was told it was not possible to pair with an existing furnace because heat pump control systems were proprietary and incompatible with a standard furnace control.

I've just signed up to the Scottish government subsidized scheme for air source heat pumps, so I'll report back to HN on this.

Which I absolutely don't get. I just had a mini split unit installed at our house here in North East, paid £1500 total with installation, and damn that thing throws a lot of heat - I literally stopped using our gas boiler, it's more efficient(and cheaper!!!!) to use this unit for heating than to burn gas. It uses like 800W of power when running but produces ~4kW of heat.

I imagine the "proper" heat pump costs a lot because it has to integrate into your central heating - heat and pump water etc. But I also imagine for a lot of people in this country 2-3 mini splits like this one would be absolutely sufficient, wouldn't cost a fortune, and would save them money(plus they can be used for cooling when needed).

They are also kind of a 2 in 1 appliance, in that they can run in reverse and cool your home, and are much more efficient at that than traditional ACs.

In the US where AC is common, summer is generally peak electricity usage. I suspect this will become true in Europe as well with the heatwaves becoming a regular occurrence.

> they can run in reverse and cool your home, and are much more efficient at that than traditional ACs.

I'd love to see a source on that. There is very little technological difference between an air conditioner and a heat pump aside from refrigerant reversing valves that allow changing which end is the condenser and which the evaporator.

A heat pump is an air conditioner that can run in reverse. Put another way, an air conditioner is a marketing term for a specific kind of heat pump. Your correct that there is no inherit efficiency different. Perhaps what was meant is that they are much more efficient than traditional resistance heating?

I guess to clarify, where I've lived the most common type of AC is a window-mounted unit. IIRC those are generally less efficient than the heat pumps getting installed today, to the point where my family got paid by our utility to replace the window units with them.

I think as a general statement it's true, however the causal reason for that is not because they're heat pumps, it's because of the market for heat pumps is different.

If you poll the current installed base for HVAC, I suspect you'd find that the (vast) majority of systems are minimum SEER rated (i.e., least efficient) systems, so SEER 13/14 (just became SEER 14 this year).

In comparison, if you're already paying the premium for the heat pump system, likely you also pay an additional premium for a higher SEER unit. Also, what I've seen when doing some online shopping that most heat pump systems marketed seem to be higher SEER. Likely, because the cost associated with additional heat pump stuff drives into a higher end market where you 'might as well' make them higher SEER as well (with inverter compressors, variable fan speeds, etc).

The bigger reason is the japanese market demands efficiency. Buyers compare running costs.

Thus Japan acting as a breeding ground for cheaper, replaceable, mini splits. The American manufacturers sold into the HVAC specialist market which was efficiency insensitive but cost sensitive. Thus a bi-partite market.

The only reason mini splits have not bankrupted the American manufacturers yet is many Americans still rely on expensive HVAC specialist to do installs. Thus mini splits extreme cost advantage is buried by expensive installs.

NG (in the US) is now about 70-80% cheaper than it was at the recent highs.

And my local utilities just got approved for massive rate increases locking in those higher prices. Of course, I probably wasn't paying the full costs this past year.

An overlooked benefit is that they actually improve comfort over a boiler in a dry climate, so if you live somewhere with low humidity they help keep the air less dry. They also give you heating and cooling.. for places that don’t have Air Conditioning it’s a worthwhile upgrade.

I assume in home that don't have ACs, that they also don't have ducts. Do these ductless homes filter their air, control home humidity, or bring in fresh air from outside?

"Ductless homes" usually circulate hot water through radiators. If you switch to a heat pump, nothing's stopping you from circulating cold water in the summer, though obviously there is a limit on the temperature delta (you can heat water much more than you can cool it). Bringing in fresh air is a manual process (open the windows), and filtering air or controling humidity is then left to seperate appliances, if done at all. Though small fans to the outside for forced ventilation are gaining some popularity for giving you automatic air exchange and filtration.

> nothing's stopping you from circulating cold water in the summer

Condensation is - air conditioners have an integrated drip tray which drains to the outside, but if you ran chilled water through radiators they'd all make puddles of condensation on the floor. Retrofitting drains might be possible but I've never seen one and I can't imagine it'd be cost-effective vs installing mini-splits.

There are many reasons why you can't just circulate cold water though a radiator to cool. As another commenter stated you will get large amounts of condensation. But the other reason is that you do not get nearly as effective of convection currents with cool versus heating. Your radiators utilize convection currents to circulate the warm air around the room. Running chilled water though the a radiator would be like having an ice cube in the corner of the room. It isn't going to cool the whole room down and will get water everywhere.

Maybe a faulty assumption; my AC-less home has a ducted oil furnace, and we still haven't removed the ducts after installing a heat pump. Another house I lived in 12 years ago had ducts for oil furnace heating but no AC. Both were 100+ years old and in the northern US.

That matches my experience. All of our older houses around here with oil heat are forced air. Radiators are uncommon. But 'older' in this case is only 100-120 years.

My ductless house has a gas combi water heater/boiler and hot water circulation system to in-wall radiators with simple blower fans.

The house also has an exhaust fan on a timer, paired with small vents on several windows around the house, to cycle in fresh outside air. But practically for much of the year we just open the windows for fresh air since we live in the temperate PNW climate, wildfires aside :(

I looked in to installing a minisplit heat pump system last year, but the quotes I got were outrageous ($25k+) plus as a retrofit it's not the most elegant integration. Someday I'd like to do the conversion and ultimately decommission the gas boiler, but at that price tag it's not happening soon.

In the short term I bought one window AC and one portable AC for a combined ~$1000. It's not ideal but we only have a few weeks a year where cooling is really needed, and a few more where it's a nice luxury but not a necessity.

Sure, but you can get a whole home.humidifier for like $300 to mitigate that issue.

My parents installed a whole home humidifier a couple of years ago. It cost way more than $300 (closer to $2k installed—maybe they just got the wrong one?), and it also costs a lot to operate each month in additional electricity usage. Having a system that doesn't require one sounds much nicer.

I got quotes in that range as well here in boulder, so I installed one myself a week ago in about 2 hours(aprilaire 700 - $310) with no special HVAC knowledge, though I am mechanically and electronically inclined.

I haven't checked the electricity usage but I can't imagine it is much. The system is literally just a small fan and a solenoid valve. Maybe your parents opted for a steam system, whereas mine is called a flow through style.

I think you got confused with DEhumidifier. Humidifiers are cheap to operate.

Nope. It's a humidifier that uses resistive heating to vaporize water, and that takes a lot of energy.

That's like cautioning about the price of cars because you bought a Hummer instead of a Corolla. Drum humidifiers use a couple watts on any central forced-air system.

And, since the heating season is there only time you need humidifying on this context, all the "waste" heat is just heating your home.

Sorry but this is incorrect. Boilers aka hydronic heat is usually delivered through baseboard fin-tube or hot water radiators. These heat mostly through convection with some radiation. Any humidity in the house is retained. Forced air heats the air and removes humidity absent a humidifier.

Forced air doesn't remove humidity from the air either. Humidity is lost through air leakage in homes. Since the air outside had less absolute humidity in the air then humidity will drop due to air leakage. Most measurements of humidity is relative humidity though which changes with air temperature. So any system that heats air will reduce relative humidity.

Neither removes humidity, only AC does that. All types of heating lower relative humidity by increasing the temperature of the air.

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