231–240 of 243 posts
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).
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> 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% efficie…
The issue with poorly insulated houses in cold climates is not about efficiency. The issue is that the thaw cycle makes it impossible to actually come up to temp because too much heat is lost during thawing. Most of the UK isn’t really considered “cold”, which is probably why you don’t have this issue.
From a quick skim around it appears ASHPs can continue to work at -20c even -30c IF they are units that were designed for cold climate operation, albeit they can't secure the same SCOP/efficiency as they can with warmer temps.
It also looks like homes in these colder areas will often install the ASHP + have some form of additional heating as a back-up (e.g. electric heating) to compensate for the limitations of the ASHP in the coldest weather.
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.
Try Toast Hawaii. The weird mix of ham, pineapple and cheese the Germans make. I am still convinced the lava cheese insulator is there only to burn people's insides with boiling pineapple.
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A heat pump gets more heat from a given amount of electricity than if the electricity is use for resistive heating. So the ideal design is solar cell + sodium battery + heat pump.
Also when the temperature differential is lower, so ideal might be solar -> battery (to time shift to warmest outdoor temperature) -> heat pump -> thermal battery (to time shift to when you need heat). Does seem like a lot of added complexity (and likely machinery cost) though.
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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.
> I do miss my natural gas on-demand water heater from when I lived in the states though. Isn't that what we call a combi boiler in the UK (and Europe?) I've recently moved from having a big hot water cylinder to a combi. The space saving is nice, but there are downsides. Waiting for the hot water to come through is annoying and I'm often just wasting cold water waiting for it to come through hot. There is a "pre-hea…
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This assumes the consumer doesn't know and can't look up the price of the hardware.
The cost of installation vastly exceeds the cost of the hardware. And the installers will only warranty hardware you buy from them.
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These are credits that only work if you have owe federal taxes and they cannot be carried forward. I've seen estimates that 40-45% of taxpayers owe 0 or close to 0.
Eh? If you have income you owe taxes, Uncle Sam just takes it before you even see it
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This is exactly the kind of thing government is for, even though it's missing the other half: subsidies. At the very least buying heat pumps for the next 5 years should be tax deductible. Even better: a $2000 or similar rebate.
That's probably exactly what will happen. Energy property - Heat pumps and biomass stoves and boilers Heat pumps that meet or exceed the CEE highest efficiency tier, not including any advanced tier, in effect at the beginning of the year when the property is installed, and biomass stoves and boilers with a thermal efficiency rating of at least 75% qualify for a credit up to $2,000 per year. Costs may include labor fo…
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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.
You are right in your analogy. Earth's oceans and seas act as giant heat sinks. And that means more trouble as global climate change impacts.. https://www.earth.com/news/ocean-warming-broke-records-for-4...
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Isn't it better to heat the water up to a point (let's say 40 or 50 degrees) and to heat it the rest of the way with resistance heating? >Versus resistance, which is exactly as efficient at 0°C and 1000°C It isn't. The difference is smaller than for a heatpump tho obviously.
1. No, absolutely not. Why would you settle for COP=1 when you can have COP>1? 2. The electrical to heat conversion efficiency is indeed 100% regardless of the temperature of the resistor. And if you're putting out 1000W, then all input losses are also identical. If you put a 1000W light bulb in the middle of your room, or 2 of them but run both at 500W, you'll get EXACTLY the same heat output in your room, but the s…