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Comment by nickdevore | Hacker News Reader

I've had mine for about a year. I put it in my garage which previously, would reach easily 100F + in the summer. This past summer, on the hottest day, it got to about 90 in the garage. When the water heater was running, it easily kept the garage below 90. I purchased the hybrid version which can use straight electricity when the heat pump won't cut it. This serves to also keep the garage cooler for the second fridge I have in the garage.

I was previously on propane to heat my water, which was costing between $50 - $60 a month. During the summer, my electricity bill only went up $12 a month. During the coldest part of winter, it was at about $30 a month more. But, I pay considerably less for electricity in the winter than in the summer.

Just for reference, I purchased the Rheem 65 gal 10 year warranty from Home Depot when it was on sale. This has definitely been one of the best purchases

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I replaced our older electric water heater with the 50 gallon version of this last month: https://www.homedepot.com/p/Rheem-Performance-Platinum-50-Ga.... The heater was about $1200, the rebate from the state of Vermont was about $800. I did the install myself with about $100 of parts.

Positives: As far as I can tell so far, the savings in electric usage should pay back within 2-3 years. It has a 10 year warranty, which should keep it working for a while. If the compressor fails, there is an electric element as backup. The device itself seems solid and well built.

Negatives: Even though it's in the basement, it's louder than I'd like --- about like an window air conditioner. Getting it down the narrow basement stairs (and getting the old heater out) was hard. Reheat is fairly slow if you keep it on the highest efficiency "heat pump only" setting. I've yet to get the phone app working to control it from upstairs. The basement is quite cool (especially in winter) so I'm worried it won't be maximally efficient. It produces a small amount of condensate water, which requires a drain of some sort.

Overall, I'm hoping it will be a win. It produces enough hot water for our 2-person needs, and seems like it should be more efficient than what it replaced. If you are considering one, it's worth thinking about the cooling effect that it will have on the room that it is in. If you already run an air conditioner, this is a win. If you are heating, this is a loss. We heat with wood in the winter (which is inexpensive if you cut your own) and don't have any other summer air conditioner, so for us this aspect is fairly neutral.

This model can be ducted with standard 8" ducting. It is possible to have it draw warm air from outside or vent the cold air out of the house. You can get fancy and install baffles that you switch seasonally. A properly ducted system will be more efficient because you won't be putting artificial house heat into the water or heating the house more to offset the cooling.

I installed it thinking I'd install ducting if necessary. But as you might guess, in the winter in Vermont there aren't a lot of available sources of warm air other than the those you create through heating. And if I vent to the outside, the resulting depressurization will just cause the rest of the house to suck in even colder outside air. The basement itself derives enough ground heat to stay above freezing, but heat pump efficiency drops as you get close to freezing.

Currently, I think I'll probably connect to an intake floor register from above, so it has better access to warmer air. I'll be trading off more firewood for less electric, which is probably a win. I'll probably also exhaust the cooler air back into the house level, on the theory that this will help a little in the summer. I'm guessing the downside will be increased noise. It's a quiet house to begin with (woodstove with no forced air) and I'm loath to make it noisier.

Do you know if there is any benefit to going with the model specific ducting kit? Or can one just buy off the shelf?

Off the shelf should be fine. It's rated for 340' of ridgid pipe or 125' of flex. I've seen people zig-zag the ducts to help reduce the noise

> We heat with wood in the winter

You should stop doing this. The impact on air quality is very bad and is disproportionately bad for the people nearest the source (i.e. you).

https://www.lung.org/clean-air/at-home/indoor-air-pollutants...

https://www.epa.gov/burnwise/wood-smoke-and-your-health

I'm not disagreeing that wood burners have a negative effect on air quality, but there are plenty of valid reasons to burn wood for heating. Not having access to a stable uninterrupted electricity supply is one reason. Cost is another reason. A good cast iron wood stove can be quite efficient and will continue to put out heat long after the wood has finished burning.

Yes, we should all aim to pollute less. But we should not attach stigma to things that for many people is their only choice of heating, transport, etc.

> Not having access to a stable uninterrupted electricity supply is one reason.

Non-electric heating systems use relatively little electricity, to the point that a small inexpensive solar panel and battery would suffice. Some don't require any. Also, this criteria doesn't apply to the vast majority of locations which do have access to the power grid.

> Cost is another reason.

Cost is generally regarded as an invalid reason for pollution. Surely it costs less to dump industrial waste in the river as well.

Also, how much money is your health worth to you?

> A good cast iron wood stove can be quite efficient and will continue to put out heat long after the wood has finished burning.

This kind of system is less efficient than modern heating systems designed for fuel efficiency, which run only when they're needed and only to the extent they're needed. Storing heat in metal rather than burning fuel as needed means burning more fuel at the start and less later, which means a greater temperature variation and more fuel required to maintain the same minimum temperature, which exacerbates the level of pollution being generated.

> But we should not attach stigma to things that for many people is their only choice of heating, transport, etc.

We should attach a stigma to things that have negative externalities, because they have negative externalities. If some people can't afford it then give them money instead of overlooking the harm they cause.

>>Cost is generally regarded as an invalid reason for pollution. Surely it costs less to dump industrial waste in the river as well.

You know, I'm feeling idealistic like this quite often, but then the reality hits hard sometimes. In Poland where I'm from apparently 35% of residential properties still use coal for heating in 2020, which to my modern sensibilities is insane, but then I speak to some of my family living outside of the cities and the reality is:

1) there is no mainline gas supply, so gas is not really an option, unless you want to pay a lot of money to have an external tank installed at your property(look at point 3)

2) electricity is far too expensive to use for heating, every back of a napkin calculation shows that it would simply eat your entire salary to heat using electricity in colder months. Electricity in Poland is both hugely expensive and almost entirely from fossil fuels, we produce most of our electricity from coal power plants(and building more of them!). I can keep telling people that "surely their health is more important than money" but it would literally by a question of "heat or food for the month" if they used electric heaters.

3) there are some "eco" options like converting your boiler to eco-pellets, but even with EU grants, realistically, it's still like 2-3 months worth of salary to fit a new boiler for a lot of people. Simply not an option.

4) coal is very very cheap. You can buy supply that will last you entire winter for about ~400USD, maybe less if you're willing to burn poorer quality coal(which theoretically shouldn't be burnt anymore but yeah good luck enforcing it).

>>If some people can't afford it then give them money instead

Again, that's cool as an idea, that's just not how it works in reality.

If you think the presence of a power grid is the same as having power 24/7, you need to spend some time in other parts of the world. In some places you are lucky to have power for 12 hours a day.

You're looking at this from a position of privilege. When I say "cost is another reason", what I'm really saying is that many people literally can't afford the electricity or the electric heater itself. The vast majority of the world's population earn no more than a few US dollars a day. They are saving for their next meal and hoping they can afford to have their shoes repaired soon. They aren't in a position to consider how they can be more environmentally friendly. They just want to survive.

You can buy catalytic converters for wood stoves.

Also, as long as you have some draft, you can add wood without releasing much indoor smoke.

> You can buy catalytic converters for wood stoves.

This is kind of like saying you can buy a catalytic converter for your car in 1950. It costs money and much of the benefit goes to people who aren't you so most people don't buy them unless required by law. Also, they're not 100% efficient so although they are an improvement they don't fully eliminate the problem.

> Also, as long as you have some draft, you can add wood without releasing much indoor smoke.

Indoor smoke is really bad, like catastrophically bad, but outdoor smoke is no fun either. It accumulates in the area and ends up back inside. This can be really bad whenever it isn't windy.

> Also, they're not 100% efficient so although they are an improvement they don't fully eliminate the problem.

True, but they're up near 90%, I think. And they also increase heat recovery efficiency, so you'll need less wood.

Consider chilling out on this a bit... There's a huge difference between a fireplace and a modern high-efficiency wood stove or pellet stove. The latter produces mostly CO2 and H2O, with far less particulate. Look at the chimney of one while running at operating temperature and it will be clear (no smoke).

Furthermore, not everyone can afford other options. It's just the way it is. I'd love to cover my roof in photovoltaic panels and get an electric car, but I'm too poor. Maybe in 15 years, if I keep savings like I have.

If you live in Vermont and burn wood year round you're probably still better off air quality wise than living in a city.

I also live in Vermont and my rates are high but decent at .115 a KwH for the first 200. After that they jump to .255 a KwH. If I did everything with electricity it would cost me $50/Mo for heating water and about 300/Mo for space heating. This is pretty close to what propane cost me back before oil prices crashed.

This is using ideal numbers from manufacturer sites and energy.gov. Given that it's Vermont and it can stay below freezing for months at a time (my basement stays around 45 in the Winter) I'm not sure ideal numbers are...ideal.

This stuff gets complicated and includes social factors, inertia, installed base and regional issues that almost certainly don't apply to you.

I recently installed a wood pellet stove which is both cleaner burning and more efficient than a wood stove. It's great. It saved me more than 50% off my heating costs. However,it's noisy, has failed twice in two years requiring expensive parts and repairs and still doesn't work when the electricity goes out. In rural Vermont you can expect at least one power outage per year that lasts more than 24 hours. Last year we had one that lasted 60 hours. Fortunately it was Winter so it was 6 degrees in the basement where the freezers were and we didn't lose the food.

Unfortunately it was Winter and our pellet stove, propane boiler and space heaters all require electricity to run so we spent a few very chilly days in a 6 degree house.

Let me start by saying I really appreciate your comments on this site. I upvote a lot of your comments on a lot of threads, and appreciate seeing what you have to say. But although wood heat is a complex issue, I don't think you are correct here. Having looked at it pretty closely, I think modern wood heat is good solution for homes in the rural Northeastern US.

Yes, air pollution is a big problem. Modern catalytic stoves are much lower on particulate emissions than older models. The one we have (https://www.woodstove.com/index.php/progress-hybrid) has about 1/10 the emissions of older models. Efficiency is also about 30% higher, which reduces CO2 emissions. With a reasonably designed system (draft that draws in outside air) indoor pollution isn't particularly an issue. Locally harvested wood is quite sustainable, and very close to CO2 neutral. We manage our forest land, and cutting wood is an essential part of this management. And mentally, it really is pleasing to feel in control of the whole process --- cut trees, burn trees, grow more trees.

Since we're not on natural gas, the best alternative at this point would probably be a solar system and an electric heat pump. As we get older, and are are less able to harvest our own wood, we'll look into it more seriously. I think for right now, though, wood burning makes good sense for us both financially and ecologically. That said, I would be interested to see any sources you might have that compare modern efficient wood stoves with the alternatives.

> It has a 10 year warranty

...

> I've yet to get the phone app working to control it from upstairs.

I wonder what the phone app support will look like in 10 years...

Wouldn't it be great if your fridge could integrate directly with the heat pump, rather than indirectly via the air in an enclosed space?

In summmer, our (California) home frequently has the air-conditioning running mid afternoon, at the same time as a gas boiler is heating the pool. It would seem to make sense to use the pool as a giant heatsink for the home AC... but that doesn't exist apparently, and any plumber I talk to looks at me like I'm crazy. "They are separate systems."

From my reading of heat pumps, mismatches in energy sources and sinks can make linking things together more complicated (aka more expensive) than is commonly available.

For the pool <-> A/C case, This Old House did a segment on linking the systems: https://www.youtube.com/watch?v=J7fB8ul9dZw

Edit: chris_va has more details about why linking systems is hard: https://news.ycombinator.com/item?id=23001888

Would be great if everything was integrated. Computers for example generate a lot of heat. Would be great if we could easily move that heat to places where it is actually useful instead of just wasting it. Looks like this is a thing in data centers:

https://en.wikipedia.org/wiki/Temperature_chaining

> It would seem to make sense to use the pool as a giant heatsink for the home AC... but that doesn't exist apparently, and any plumber I talk to looks at me like I'm crazy.

You are not crazy. IBM did that.

https://en.wikipedia.org/wiki/Green_data_center#Reusing_wast...

> The IBM Reusing Data Center in Switzerland, where the heat warms a local swimming pool

Also:

https://en.wikipedia.org/wiki/Data_furnace

It does exist, and those plumbers are wrong. The biggest challenge is finding a heat exchanger (to replace the one in your AC condenser) which is designed to survive highly corrosive hot swimming pool water.

The UCDavis Western Cooling Efficiency Center [1] has done extensive research on this, sponsored by the California Energy Commission.

In a nutshell, they found that using your swimming pool as a heat sink for your air conditioner can reduce cooling energy consumption by 30% or more (not including the reduction in pool heating energy consumption). The two main caveats:

1. Many pools are too small relative to the house to be an effective heat sink without overheating the pool.

2. Increased pool temperature causes increased evaporation, resulting in increased water consumption (also a problem in CA).

They also found that adding a fountain for evaporative cooling of the pool can mitigate #1, at the expense of worsening #2.

[1]https://wcec.ucdavis.edu/

Wow, I'd never considered that aspect of a heat pump before. But it makes sense -- a heat pump is (conceptually) just a backwards air conditioner, after all; it stands to reason that it'd make the room colder while it's operating.

My thermodynamics book in college (Cengal and Boles?) had a (Blondie) comic with The exchange:

“Are you air-conditioning the outside?”

‘No, I’m heating the house!’

50$ a month for hot water seems really high? I’ve never gone over 20$. Anything you want to tell us?

Water usage basically scales with household size. GP probably isn't a single dude living in a studio apartment taking navy showers and planning his meal prep to minimize dish washing. Combine that with an electric water heater (almost always more expensive to run than natural gas) and a nearly triple digit electricity bill isn't surprising.

Propane, I’d guess. With propane, you are paying someone to truck propane to you and pump it into your tank. You are also paying all the costs of owning and maintaining the tank.

If you live in a place with reliable electricity, I don’t think propane really makes sense any more. You can get heat and hot water from heat pumps, and induction stoves work well and are vastly more efficient than gas.

In rural areas, where propane is common, with some density (1-5 acre lots), lots of places converted to natural gas after the fracking boom.

That’s not to say that propane is still not common.

You get natural gas delivered? What’s so special about propane anyway that it’s the defacto portable gas?

It’s liquid at ambient temperatures under pressure so it transports and stores well. Also it’s a tad more energy dense than natural gas.

Propane has higher energy density, can be liquified by compression, and doesn't need cryogenic tanks.

Propane is easily transported and stored as a moderately pressurized liquid at ambient temperatures. Propane has a big volumetric advantage over natural gas. Natural gas is mainly methane, liquifies at -160°C, and requires active refrigeration. If your use point is within natural gas piping range, gas is usually the better choice. Propane is the choice for locations not served by piped natural gas.

Fun factoid: Propane leaks are far more dangerous than methane leaks. Methane is less dense than air, so it tends to mix more fully. But propane is more dense than air, so it tends to pool near the floor. And the lower flammability limit for propane is lower (2.1% vs 5.0%). So you reach the lower flammability limit faster. Plus the fact that pilot lights are often near the floor.

Induction is alright, and some people prefer it. Vastly superior to radiant electric.

If you really like cooking on gas (I happen to) the expense of running a propane range is insignificant compared to the amount of propane you'd burn to heat water or a home.

Why would you go with propane? Natural gas is ubiquitous and everywhere (at least in the US). Maybe it's less so in the south? In the north it's mandatory for not dying in the winter unless you're so rural that you need to chop wood to stay warm.

in rural Sierra Nevada foothills California counties there is not ubiquitous natural gas

No, natural gas is not ubiquitous. Maybe within certain urban and suburban areas, but once you get a little rural you are out of luck.

Then again, a lot of people don’t realize cable internet isn’t a given, even within 15 minutes of the capital city of a state in the contiguous United States. They also don’t have natural gas available. :-)

Water and sewer too.

Copper telephone and electricity are the only two utilities you can count on in the most rural 10% of America.

In rural eastern Oregon, there is not ubiquitous natural gas.

I don’t think anybody chooses propane over natural gas, but natural gas is unavailable to a great many people.

In suburban NY you don't have ubiquitous natural gas. Some, but not all, new developments are natural gas, but many existing ones are heating oil. Propane is also a possibility, but much more expensive so is not used as often as oil except for cooking.

Before we a) put in PV and b) got that heat pump water heater, we paid about $50 for our hot water heater electricity use (~160kWh/month) here in HI.

I wouldn't try and cool down a garage or try and maintain a temperature in it to be honest, they're usually very poorly insulated so it'd be a huge waste of energy.

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