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| Miyuki:
Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses. 10 or so years ago was common to install heat pumps rated to 15-25kW output in old uninsulated houses. The cost of the bigger pump was still cheaper than house insulation. And making the heat pump bigger can be relatively inexpensive. Two times bigger compressor does not cost two times but just lower tens of percent more. The evaporator is also relatively cheap and the expensive control electronics remains the same. |
| Monkeh:
--- Quote from: Miyuki on February 22, 2023, 09:20:10 pm ---Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses. --- End quote --- 'just' replace every radiator in the building and all the pipework. Five minute job. |
| coppice:
--- Quote from: Miyuki on February 22, 2023, 09:20:10 pm ---Just use suitable radiators to have a 45°C system, it is not a problem, they are thicker and have denser fins inside, but they definitely can be fitted to old uninsulated houses. 10 or so years ago was common to install heat pumps rated to 15-25kW output in old uninsulated houses. The cost of the bigger pump was still cheaper than house insulation. And making the heat pump bigger can be relatively inexpensive. Two times bigger compressor does not cost two times but just lower tens of percent more. The evaporator is also relatively cheap and the expensive control electronics remains the same. --- End quote --- If you are going to that much expense and disruption, why would you use radiators at all? If you want radiators to run at 45C in most rooms you will need to used forced air. A passive radiator would be huge. You might as well force much cooler air around the entire house, and get a much better COP from the heat pump. |
| tom66:
--- Quote from: Monkeh on February 22, 2023, 09:21:16 pm ---'just' replace every radiator in the building and all the pipework. Five minute job. --- End quote --- Hmm, radiators aren't *that* difficult to change if you're also going to be installing a heatpump. Doing insulation throughout though, that requires redecoration and most rooms to be emptied out, so isn't really trivial. |
| nctnico:
--- Quote from: tszaboo on February 22, 2023, 09:28:16 am --- --- Quote from: nctnico on February 21, 2023, 07:54:43 pm --- --- Quote from: Ice-Tea on February 21, 2023, 07:28:22 pm --- --- Quote from: nctnico on February 21, 2023, 07:00:26 pm --- --- Quote from: Ice-Tea on February 21, 2023, 06:36:29 pm ---So, uhm, that's your argument then? You disregard any data that doesn't fit your narrative and call all those that run with it idiots? :o --- End quote --- There is no narrative and there is no argument. Just the fact that heatpumps are not economic to run when it is cold. This is obviously clear from looking at specifications from actual heatpumps. There is no need for yet another fantasy number that is invented to compare heatpumps because it says nothing about the suitability of heatpump for a less insulated home. --- End quote --- But.... it does. Nobody is arguing that the efficiency of a heatpump goes down when temperature does. That's why you have the SCOP value. It tells you what your seasonal efficiency will be. And it does say something about suitability for less isolated houses as you typically have this value for 35C and 55C feed temperatures. And if 55C doesn't suffise: get crackin' on isolating your barn, please. --- End quote --- If you look at what SCOP actually means, you'll notice it is not a number that tells you something about the suitability of a unit. Seasonal efficiency doesn't mean that a unit will be able to heat a home when it is cold. The COP might be too low and SCOP doesn't tell you that at all. Also, you don't need high water temperatures perse. It is relatively easy to retrofit an existing home with underfloor heating (been there, done that) which doesn't need high water temperatures at all. --- End quote --- Why do you think this is happening? Do you think that this is a huge mistake that half the households are doing in these countries? --- End quote --- You keep missing the point here which has been explained by several people already. But I will repeat is once more so you may finally understand it: a heatpump can only work for a home that is well insulated. When the COP bottoms out, it has still has the capacity to provide enough heat through resistive heating. However, in many countries that have relatively mild climates (like UK, NL, Germany), homes (especially the older ones) are not insulated well enough to be heated with a heatpump all year long. It is logical that you see heatpumps in countries with colder climates because those homes are way better insulated already and thus suitable for heating by a heatpump. It is not about black / white, heatpumps bad / good, it is about suitability. I have been using the word 'suitable' a lot but people keep missing it. |
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