Heat pumps of the 1800s are becoming the technology of the future • Hacker News Board

Re: Heat pumps of the 1800s are becoming the technology of the future

#41

Post by rsynnott » Mon, Jan 16, 2023, 5:29 PM UTC

macinjosh wrote: post #30

jakedata wrote: post #19

In 2017 we installed a very efficient air-source heat pump and solar panels. My electrical utility offers 1:1 buyback of electricity so I am able to build up a credit in the summer and run the heat pump well into the fall and winter on that surplus. The system is sized for cooling the house which means that it is undersized for heating, but during cool fall and spring temperatures it operates satisfactorily as a heat…

Still waiting for one of these people who rave about their heat pump system to actually rely on it full time without a backup. Most folks could barely afford to replace an existing furnace in a place that has all the fixtures installed, much less pay to install a second one based on different setup, and then pay for maintaining two systems on top of everything else. It is absurd to think that this is a plausible way…

> Still waiting for one of these people who rave about their heat pump system to actually rely on it full time without a backup.

Eh? Most new houses in Ireland have them these days (it's more or less the only way to meet the efficiency requirements). There's never a backup.

> Same thing for induction stoves.

Eh? Again, these are pretty standard these days, and why would you need a backup?

Re: Heat pumps of the 1800s are becoming the technology of the future

#42

Post by LatteLazy » Mon, Jan 16, 2023, 5:29 PM UTC

Everyone is looking for an easy answer to climate change / energy costs / energy independence etc. But there isn't one. Fusion remains decades away, Fission is very expensive and unpopular, Most renewables are intermittent etc. Heat pumps are one more tech with very limited potential (range of temperatures, efficiency over that range, power output limits, need for a heat source, size, cost etc).

Re: Heat pumps of the 1800s are becoming the technology of the future

#43

Post by ComputerGuru » Mon, Jan 16, 2023, 5:30 PM UTC

ghettoCoder wrote: post #16

retrac wrote: post #10

Earlier quoted context omitted.

> it seems crazy that I warm the air of my house and then use electricity to keep the fridge cooler than the air I just heated The fridge is simply moving a little of the warmth in your room out of its box, and adding a little more warmth to the room in the process. You lose no heat from the room, which is what matters, really. It would be worse to dump the heat outside! At least in winter. The heat has to be removed…

I always joke that in winter all appliances are 100% efficient (I know they're not). Some look at me funny but the ones who pay the gas bill get usually get it.

This is the first year where heating the home with gas isn't an order of magnitude cheaper than with electricity here in the Midwest. Gas still wins, but not by as large of a margin!

Re: Heat pumps of the 1800s are becoming the technology of the future

#44

Post by zdragnar » Mon, Jan 16, 2023, 5:30 PM UTC

fasteddie31003 wrote: post #8

I had a similar idea when I was designing a heating system for a mountain house I was planning on building. I was planning on primarily heating with an oversized wood stove. The excess heat the wood stove would produce would be captured by a heat pump inside the house with its coils in a 500 gallon tank of water that was well insulated. When the house needed heat you could run the heat pump in reverse or make a syste…

Outdoor wood boilers have been a thing for a long time. Back when I had mine, it kept the water at 180F.

https://en.wikipedia.org/wiki/Outdoor_wood-fired_boiler

If you have enough sufficiently dry wood, downdraft gasification models burn extremely cleanly (they're effectively rocket stoves), but those models require a fair bit of maintenance, especially if your wood is slightly wet or green, because soot can quickly build up on the water envelope.

Re: Heat pumps of the 1800s are becoming the technology of the future

#45

Post by TeMPOraL » Mon, Jan 16, 2023, 5:31 PM UTC

jdmichal wrote: post #37

ballenf wrote: post #28

Earlier quoted context omitted.

I've often wondered if opening windows while AC is running and outside temp is below inside temp is less efficient than keeping them closed. My thought is I should keep them closed due to extra load on the AC to dehumidify the outside air. Or open windows and turn AC to fan-only mode to prevent stagnant air in rooms without windows.

Unless you have a very strange setup, centralized A/C does not have humidity sensors nor run just to dehumidify. Nor does removing humidity increase the load on the A/C system. Removing humidity is just a happy by-product of how centralized A/C works. So no, you would not be increasing load for that reason.

Happy in some times, unhappy in others. There are days I'd love if the A/C would have a humidifier built-in, for those winter months when you might want to use A/C to warm the interior.

Re: Heat pumps of the 1800s are becoming the technology of the future

#46

Post by rini17 » Mon, Jan 16, 2023, 5:33 PM UTC

Interesting! Do I understand correctly that the additional water storage just cycles between 0°C and below room temperature to further cool/preheat the coolant? Hard to believe it could have such a big effect.

And how does it fit into existing setup? I can imagine it can be connected before water boiler to supply the lukewarm water.

Re: Heat pumps of the 1800s are becoming the technology of the future

#47

Post by renlo » Mon, Jan 16, 2023, 5:35 PM UTC

Wouldn't using a lake as a heat/cooling source cause "thermal pollution"? It's probably fine if a couple houses surrounding the lake use it, but if the technology begins mainstream enough to where everyone is using it, it could cause a lot of issues for the flora and fauna of that lake / downstream habitats.

Re: Heat pumps of the 1800s are becoming the technology of the future

#48

Post by wpietri » Mon, Jan 16, 2023, 5:35 PM UTC

LatteLazy wrote: post #42

Everyone is looking for an easy answer to climate change / energy costs / energy independence etc. But there isn't one. Fusion remains decades away, Fission is very expensive and unpopular, Most renewables are intermittent etc. Heat pumps are one more tech with very limited potential (range of temperatures, efficiency over that range, power output limits, need for a heat source, size, cost etc).

Wait, you are telling a bunch of technologists that no technology is perfect? Stop the presses! Which, dang it, are clearly also an imperfect technology if we have to stop them every time there's fresh news.

Re: Heat pumps of the 1800s are becoming the technology of the future

#49

Post by PinguTS » Mon, Jan 16, 2023, 5:35 PM UTC

Sorry, but I don't see any novelty here. Everything described in the article is commercially available. At least here in Germany.

Heat pumps are used to heat a storage container called buffer, a water container of 200l or more of water. This is used to run the heat pump when energy is cheap to warm up the buffer. That is for example in daytime when energy is available from the photovoltaic. If you don't have photovoltaic you can also have a good energy price when running this at night.

Also the storage of the heat in summer is nothing new. These systems are also commercially available for years. It is only that they are so expansive that many companies have backed out of those.

The idea here is that in summer time you heat up a big tank in the ground like with a thermal system on your roof. Then in winter time you use that "saved" energy to run the heat pump. At the end of the winter the water in the tank will likely be freezing. That state change of the water will give an additional energy boost, because it is the same amount of energy you need to boil water. All this is well known and working and commercially available for years.

Re: Heat pumps of the 1800s are becoming the technology of the future

#50

Post by richjdsmith » Mon, Jan 16, 2023, 5:36 PM UTC

ddalex wrote: post #20

mikewarot wrote: post #14

For our house, a ground loop heat pump would be best. A long slit trench, with the slinky style of coolant loop, in the back yard (away from utilities) could easily handle all our waste heat in the summer and source heat in the winter.

Wouldn't it be cheaper/easier to dig a well, fill it with tubing, and pouring concrete all over? The concrete being the constant-ish temperature heat reservoir ?

My parents built a new home a couple years ago. The property had a well despite being on city water. They have other homes with ground source heat pumps. When asking the geothermal contractor if they could use the same well borehole, the contractor said why don’t we just circulate the water and not bother the existing well. So that’s what they do - their geothermal system uses the well water, circulates it through the condenser, then sends the water back down into the ground.