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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

#201

Post by footydude »

IshKebab wrote: post #190
ifwinterco wrote: post #161

Earlier quoted context omitted.

Houses in the UK typically have 100A supply and the whole local grid is sized assuming people use relatively small amounts of electricity. If everyone gets an electric car and a massive heat pump, lots of local transmission will need upgrading

Right but unless everyone is drawing large amounts of power at the same time it doesn't matter if you use 1kW for 10 hours or 10kW for 1 hour. To the grid they look the same. One interesting case where "at the same time" actually does happen is overnight car charging. Some chargers are configured to start charging exactly when a cheaper tariff kicks in, which causes big transient issues for the grid. I think modern c…

> Some chargers are configured to start charging exactly when a cheaper tariff kicks in, which causes big transient issues for the grid. I think modern chargers have a random delay to help with that.

Here in the UK some electricity providers offer 'smart' charging (e.g. Octopus Intelligent Go).

In that situation the energy provider controls when to charge the car - e.g. you say "I want the car at 80% by 7am tomorrow" and the energy provider controls the timing of charges.

That's how my EV charges - I plug it in, and Octopus control it.

Benefit for me is that whenever the car is charging my entire home's use gets the overnight rate (even if part of the schedule is charged during the day).

Benefit for Octopus is they can use my car to balance grid demand / schedule the charge when it is most financially effective for them.

I can - at any time - override that logic if I just want it to charge at a specific time for whatever reason.

(I presume this sort of arrangement is becoming more common in other countries too)

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

#202

Post by footydude »

hippo22 wrote: post #153
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.

It really depends on how well your home is insulated. Heat pumps don’t work well on old, poorly insulated houses in cold climates. If they can keep up, which is a big if, the price of electricity generally dwarfs natural gas, even if the heat pump is running at 250-300% efficiency.

> Heat pumps don’t work well on old, poorly insulated houses in cold climates. If they can keep up, which is a big if, the price of electricity generally dwarfs natural gas, even if the heat pump is running at 250-300% efficiency.

I've got a 1930s semi-detached house (UK, north of England) - heated solely by a ASHP for both heating and hot water.

Our Seasonal Coefficient of Performance is currently 3.47 (347% efficient) - even if limit that to just last month (coldest month of the winter so far in the UK) our COP was 3.25 (325% efficiency).

Roughly speaking if you can achieve a COP over 3.2x in the UK it should be roughly on a par with gas, assuming you go 'gas free' (i.e. you can make the saving on the gas standing charge).

Personally we're running at ~£200 annual saving vs. my estimate of what costs would be for equivalent gas boiler - that's thanks in part to being able to do all our hot-water heating at night rates.

House wise - we don't have cavity wall insulation, have 15+ year old double-glazing and probably should have more insulation in the loft (it fills the rafters but I think these days that's considered not enough).

Also with changes to ECO (energy company obligations) and RO (renewables obligations) the differential between gas and electric will reduce further

Anyhoo - added my example to show that ASHP can work perfectly fine in old, poorly insulated homes in (moderately) cold climates.

ECO/RO link - https://www.moneysavingexpert.com/news/2025/11/energy-bill-c...

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

#203

Post by elric »

hnburnsy wrote: post #12

Related, TIL the US is effectively banning residential electric resistance water heaters in 2029, with heat pump water heaters being the only type that can meet the new standards. Users will see a 2-3x in cost difference and a 3 to 8 year payback on savings.

That seems like a stupid ban. Heat pump water heaters are impossible to install in many smaller dwellings, even if we're ignoring the need for large storage tanks.

The only problem with resistance heaters is the large current draw to heat water for bathing. Central heating can be done at lower temperatures (as is the case with heat pumps), but bathing cannot.

There are some resistance heaters with built in (electrochemical) batteries aimed at reducing peak current, but I'm assuming the ban would affect those as well...

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

#204

Post by stratosmacker »

ProllyInfamous wrote: post #172
moooo99 wrote: post #169

Earlier quoted context omitted.

It does. However, the hotter the water becomes, the less effective the heatpump becomes. With anything beyond 60C becoming very inefficient. With hot water tanks, they are unfortunately pretty badly insulated as well, with some of them loosing heat very quickly. Depending on how you plan on using that water, you also have to make sure the temperature never dips below ~60C to avoid legionella from spreading. I actuall…

I have two heat pump water tanks, one Rheem and one AO Smith (our local utility heavily-subsidizes these, with a net-cost less than a standard tank water heater ). They both are rated for annual kWH usage less than the US EPA yellow label can display (for their category of tanked water heaters , i.e. competing mostly with resistive heating models). Annually water heating is about 3% of my energy consumption.

Do you prefer one to the other? I’m in the market

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

#205

Post by account42 »

LoganDark wrote: post #115
Loughla wrote: post #97

Earlier quoted context omitted.

And yet, if you make it like I do, there always manages to be one piece that is ice cold while the rest is shockingly hot. Even if you're start with warm ingredients. Physics does not apply to lasagna. Also I suck at making lasagna.

I don't know how you cook your lasagna, but cooking for longer at a lower temperature usually results in more even heating than cooking for less long at a higher temperature. (This is one of the reasons microwaves are so terrible at heating evenly.) If you're not already, that may help. (I also imagine using the circulation in a convection oven might help as well. Also, preheating your oven! Even if it's a toaster ov…

Preheating isn't really important for most things, essentially anything that doesn't specifically call for very high temperatures. The main thing it gets you is more predictable baking times which is important if you need a number to print on a box that will work in most ovens but less so when you just leave something in the oven until it is done.

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

#206

Post by shellfishgene »

ZeroGravitas wrote: post #30
chickenbig wrote: post #28

Perhaps I am missing something; this product already exists as the Sunamp Thermino. https://sunamp.com/en-gb/hot-water-solutions-thermino-range/

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.

I think the advantage is that hot water loses heat over time, depending on how good the insulation is. However with phase change materials, the heat is trappped in the phase change and is stable until you release it.

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

#207

Post by sokka_h2otribe »

chankstein38 wrote: post #57

They should've used lasagna. You could be in a tundra heating it over a fire and, as long as you get it sufficiently and consistently hot, it'll still burn your mouth 20minutes later.

To whatever degree you are serious, this can be a phase change thing.

Cheese melting takes energy Cheese freezing, releases energy.

So you do actually get the temperature to remain at the melting point of the cheese for a longer period of time if you have enough % cheese to be significant.

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

#208

Post by LunaSea »

luckystarr wrote: post #78
matwood wrote: post #67

Earlier quoted context omitted.

I think a heat pump only for water isn't the right way to go. In the EU, new systems I see use a single heat pump for all heating and cooling in the house including heating water. I do miss my natural gas on-demand water heater from when I lived in the states though. Unlimited hot water was nice, and it took up almost zero space.

While they are not as efficient or flexible, they are many times more efficient than resistive electric water heaters. I've installed one with in house air intake (due to construction reasons) in my house and it cooled down the basement by a few degrees (and removed air moisture as an added bonus). In summer the thermal capacity of the ground heats up the basement again, in winter it's a bit cooler, but it still work…

They are efficiënt but all that efficiency is eaten up by electricity being more expensive than gas.

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

#209

Post by IneffablePigeon »

moooo99 wrote: post #169
jcattle wrote: post #165

Earlier quoted context omitted.

Does heating water in a boiler work well with a heat pump? How about a release of energy 10 hours later (peak solar at noon, to first shower the next morning)? I actually don't know the answer. I'm just thinking that there must be more to it, if the answer was as simple as "just heat water".

It does. However, the hotter the water becomes, the less effective the heatpump becomes. With anything beyond 60C becoming very inefficient. With hot water tanks, they are unfortunately pretty badly insulated as well, with some of them loosing heat very quickly. Depending on how you plan on using that water, you also have to make sure the temperature never dips below ~60C to avoid legionella from spreading. I actuall…

The legionella thing is a little overblown fwiw. 50 degrees is perfectly adequate, and you can go lower with very little risk if you set it to briefly bump up to 60 every week or two. Even that is not hugely necessary in a domestic setting.

https://www.heatgeek.com/articles/legionella-and-water-tempe...

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

#210

Post by Tor3 »

manmal wrote: post #185
Tor3 wrote: post #156

Earlier quoted context omitted.

Hm? Around here oil was never been in the same (low) order of magnitude. Those who installed oil heaters many decades ago regretted it quickly. And it's been illegal to use them for a couple of decades as well now. Gas has never been an option in my region, there's no infrastructure for that. We have used gas in Japan until now, but even that we'll be phasing out (I live in two places)

> Those who installed oil heaters many decades ago regretted it quickly. That really depends on the oil heater, no? You can't compare a heater from the 70s with a modern one. That's like saying I don't drive modern cars because cars in the 70s were unsafe and stank.

Needing an oil tank, smell, expensive (oil price typically increased drastically compared to the beginning), pollution, and, as I said, made illegal in cities for various reasons, pollution and expenses related to dig up and get rid of the oil thank, and more.
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