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Pretty soon, heat pumps will be able to store and distribute heat as needed

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Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#101

Post by themafia »

Nition wrote: post #58
ZeroGravitas wrote: post #30

Earlier quoted context omitted.

It also exists, as described in the headline, as a tank of heated water. The phase change stuff has positives like taking up less physical space but it's also a much less mature tech than storing hot water.

It's funny how useful water is for power generation. There's heat storage as discussed here. Or you can store cold water in a reservoir as a giant battery, pumping it up high when you've got excess power, and letting it back down to generate hydroelectricity from it later. Or you can boil water to make steam that spins a turbine and use it to convert anything that can heat water (coal, oil, nuclear...) to electricity…

> It's funny how useful water is for power generation.

It's gravity that does the generation. Water is convenient because it's weight per unit of volume is very high. Higher than most things we can get our hands on and it's also exceptionally safe.

Since water isn't perfectly clean the main problem you face is corrosion. Which can take a great system and turn it into a nightmare of buried leaks and sudden problems.

As far as our options go it _is_ really convenient.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#102

Post by butvacuum »

IshKebab wrote: post #99
gwbas1c wrote: post #90

The article omits some critical details: It says this is both a "heat pump" and also "storage" AND says that it will run when electricity is cheap or plentiful. Thus: 1: Where does it pump the heat from? (Or is this not really a "heat pump" and instead is using resistive heating?) 2: How long does it store heat? Is this something that will store heat on a 24-48 hour basis, or will this store heat during the spring /…

1. The device is just storage. It would be paired with an air or ground source heat pump. 2. With good insulation you can easily store heat for a day which is all you need. You're never going to get close to storing summer heat for the winter. That's not impossible but not feasible for something this scale (and not cost effective at any scale). 3. You just heat it up and cool it down. There are no fancy chemical proc…

the only new thing- no matter how they do it- is putting it on residential instead of commercial or industrial installs.

my childhood public school took us to some big commercial building- I think it was Sears' HQ- and they proudly showed us the huge blocks of ice providing chill during the day.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#103

Post by gwbas1c »

baggachipz wrote: post #86
gwbas1c wrote: post #84

Earlier quoted context omitted.

You're about 20 years behind. My heat pump is working great at 0F. It's 7 years old.

heat pump for house !== heat pump for hot water

There's a lot of different heating systems: If your heating system uses hot water at any point, (baseboards, hydro-air, underfloor, ect,) using a single heat pump makes a LOT of sense.

Personally, I prefer an air-source heat pump hot water tank. It significantly dehumidifies my basement.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#104

Post by manmal »

a_better_world wrote: post #63
DrScientist wrote: post #34

Earlier quoted context omitted.

Indeed. In the UK there was a unfortunate trend of ripping out these energy storage devices and replacing hot water tanks with on demand electric hot water heating ( only heat the water you need ). And new builds often have no tanks ( as it saves space in the new tiny homes ). Very short sighted in my view - a very simple way to store energy and everyone uses hot water directly.

My hot water tank once fell off the wall. On Christmas day. Expensive repair. Hot water tank was in the basement, which was not insulated. So the mass of hot water contributed very little as a heat reserve for the house. House was in a northern clime.

Those are great for buffering only a few hours though. That would help avoid the expensive electricity price peaks.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#105

Post by manmal »

stuaxo wrote: post #73
Tor3 wrote: post #66

Earlier quoted context omitted.

I had a heat pump installed in 2010. In a cold climate. Only used for heating. It paid for itself extremely quickly - less than three years. It's still going strong, in 2026. It's important to maintain it regularly, i.e. deep cleaning every two years or so. The first time I got a company to do it for me, and the technician taught me how to do it all by myself, so that's what I do. In any case having a professional do…

What did you heat with before?

Certainly not gas or oil, which are still cheaper to heat with than heat pumps.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#106

Post by manmal »

syntaxing wrote: post #7

With the adoption of sodium batteries, I wouldn’t be surprised if solar panel + sodium battery would outperform this system by a lot.

Climates that need a hot tank of water to buffer for heat pumps, will not have meaningful solar panel output during winter. Or do you mean, just load the battery when electricity is cheap? A tank of water is 1k max, probably 10% of a sodium battery.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#107

Post by Youden »

syntaxing wrote: post #7

With the adoption of sodium batteries, I wouldn’t be surprised if solar panel + sodium battery would outperform this system by a lot.

Even LFP batteries can work out better.

I live in Switzerland where these are available. A Cowa 58 [0] costs CHF 4692 [1] and stores up to 13.5kWh. If you're heating the water with a heat pump, that's ~6kWh of electricity, so ~CHF 782/kWh.

I'm in the process of installing a 33kWh battery and the battery + inverter cost CHF 13600 in total for just the hardware, so ~CHF 482/kWh.

If you add solar panels, the inverter does double-duty producing AC from both the battery and the panels. The battery does double-duty producing both hot water and allowing you to use solar energy outside the times when the sun is shining.

That said, having ordered a heat pump recently and being in the process of having solar + batteries installed, the amount of electrical work needed for the solar/battery install is substantially higher than was needed for the heat pump and here, the labour costs quite a lot, pushing the upfront cost difference even higher.

I think that's where these heat storage things fit in: they have a much lower upfront cost. No matter how cheap the battery, for it to be useful in a Swiss residence, it needs to output a substantial amount of 3-phase power (3-phase is standard here, even in most apartments), which means you need to spend a couple thousand Francs on an inverter and electrical work. These heat storage devices are quite cheap and don't even need someone qualified to handle refrigerants, I imagine they could be installed by a normal plumber.

That reduced upfront cost makes them far more accessible than electrical batteries, at least for now.

[0]: https://www.cowa-ts.com/uploads/files/Dokumente/Datenblaette...

[1]: https://nettoheizungshop.ch/Cowa-COMPACT-Cell-58

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#108

Post by coryrc »

DrScientist wrote: post #34
ZeroGravitas wrote: post #30

Earlier quoted context omitted.

It also exists, as described in the headline, as a tank of heated water. The phase change stuff has positives like taking up less physical space but it's also a much less mature tech than storing hot water.

Indeed. In the UK there was a unfortunate trend of ripping out these energy storage devices and replacing hot water tanks with on demand electric hot water heating ( only heat the water you need ). And new builds often have no tanks ( as it saves space in the new tiny homes ). Very short sighted in my view - a very simple way to store energy and everyone uses hot water directly.

They don't work well with heat pumps. Heat pumps lose efficiency as the differential increases, so if you try to store heat in a tank, you quickly drop capacity and efficiency.

Versus resistance, which is exactly as efficient at 0°C and 1000°C, and why those storage heaters used to make sense.

(And storage is directly proportional to temperature differential above interior ambient)

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#109

Post by 5ersi »

It uses phase change (solid to liquid) to store heat at about 200 kJ/kg. Compare this to heating water in a boiler from 10c to 60c - stores 209 kJ/kg.

So we already have an effective way to store heat which can work for decades without servicing and is also cheap to produce (in terms of money and energy consumption).

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#110

Post by wffurr »

AlexandrB wrote: post #82
lm28469 wrote: post #41

Earlier quoted context omitted.

Depends on the model, but a lot use the air from their own room, that's why they can't be installed in small rooms. Models pulling the heat from outside are more expensive and require more labor obviously, and they don't make a lot of sense for places that are bellow 0c multiple month a year as the COP will drop to 1.x and you will most likely need extra electricity for the anti frost cycles

But dumping the waste cold air into the house when it's below 0C outside doesn't make much sense either.

You already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different?

It does seem a little silly to have these chains of heat pumps all working in various directions. I read about "cold district heat" in a sibling comment which circulated lukewarm water to use as a heat sink or source with heat pumps. Maybe something similar could be done with a water or refrigerant loop through the house. Probably not economical to do all the plumbing though.

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