It's weird that heat pumps are seen as so exotic and complicated when they're really just air conditioners plus reversing valves.
this post was submitted on 26 Jan 2024
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- Air conditioners in UK houses are pretty weird and complicated
- Potentially having to rip out aall the (usually underfloor) pipe work and replace all your radiator is pretty complicated, compared to switching out the existing gas-fed box on the wall
- Working out the capacity needed to heat your home is pretty complicated
- Finding the space outside in a small urban garden than can take the unit, without annoying the neighbours next door with the noise can be pretty complicated.
The capacity calculations and potential noise complaints are the big ones imho.
I can definitely see issues with installers not giving a toss about noise, and having to be chased later.
Calculating capacity isn't that complicated, you can look everything up to work it out (wmk losses, etc.), but it is a step up from the current "slap a new boiler in" mentality.
And I wouldn't be surprised if most heating techs don't consider requirement at all when changing a boiler, they'll just put in a big one, and run the rads at 70 if the client complains.
There is talk about ASHPs that can still maintain efficiency at higher temps, which may help a lot of households avoid changing the radiators too. But it's still early days.
You can leave the pipes there. They're not doing much. Radiators aren't much threat either, unless you trip into one.
Not really. Since the radiators operate at a substantially lower temperature, you may well have to replace them - you need larger, more efficient radiators than may be typical with gas-fired systems
Oh, using the same system, instead of switching to forced air.
... why does efficiency matter if the heat stays in the house? They're just always-warm instead of sometimes-hot, yeah?
We don't tend to use air/air heat pump systems in the UK, even for new builds, always air/water.
Because of lower water temperature output of heat pumps compared to the gas boilers they replace, usually you need to increase the size of radiators to be able to achieve a room temperature change in a reasonable time. What is being referred to as efficiently, is actually just a measure of performance of the radiator, not actual energy efficiency.
What an odd way to encourage people to get heat pumps.
‘It’s much simpler than you think : Experiment with your flow temperatures, get your pipes widened if necessary, and if that doesn’t work, get on twitter and hope that a random software engineer outside the industry can get you sorted ‘
It's more an article about the barriers that the industry needs to sort out, I think
I just had one installed in Canada during that -30C > -50C cold snap on the prairies. I paired it up with a backup LNG furnace for the coldest of cold snaps we get. It’s only been a couple of weeks but it has not warmed up enough for the pump to kick over. I plan to keep detailed notes this year to compare data.
A lot of the people I know and work with think these things are a fad/gimmick/wont work in Canada… I aim to prove them wrong!
-50C !!! When did that happen?
Here is a comment with a picture of my weather app from that weekend.
A couple of weeks ago on a Saturday. The actual outside temp was -50 overnight but “feels like” -60.
I'm curious about a similar setup, but want resistive electric heat instead of a gas furnace so that I could completely eliminate the gas bill since you pay fees wether you use gas or not.
Not my personal story, I hasten to add, but I found it very interesting.
Yeh, interesting article, ty
This explains why heat pumps are getting a bad reputation in the UK. Basically, no one knows how to install them properly.
I saw that about at week ago. Seems to be getting pushed in the algorithm.
The TL; DW for people:
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The installer didn't place the heat pump on a solid level base. This resulted in the unit not being level, which caused bearings to wear at a highly accelerated rate. Killed the unit in a couple of years.
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Hugely over-complicated plumbing install which introduced unnecessary heat exchanging between water loops and mixing of heated & return water. All introduced losses. The unnecessary components in the system just added expense.
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Due to the unnecessary losses, the heat pump had to run at a higher temperature for the system to work. Hence the heat pump was a much more expensive unit than really needed. (Dual stage with two refrigerants rather than single stage).
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The water tank used was unsuitable for a heat pump fed system, having too short a heat exchanger for the water temperature being fed to it.
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The system was set to a fixed temperature with no weather compensation curve. The system was always working as if it was a really cold day, killing its efficiency and putting it under more load than necessary.
The fix would be to simplify the system and reinstall the unit on a proper base, replacing it with a smaller cheaper one. Basically the guy was completely mis-sold by a dodgy company.
So…these heat pumps are doing recirculating hot water systems? I presume they have a heat exchanger that either heats the flow directly or has a (small?) reservoir tank that connects to the legacy system?
I ask because nearly every heat pump in the US is forced air and I’m not even aware (and I work in the architecture industry) of a residential product that uses an exterior heat exchanger to heat water. Your outdoor heat exchangers are indistinguishable from ours (the small units we refer to as “mini-splits”).
Forced air is vanishingly rare in the UK, because air conditioning is vanishingly rare as a built in system in residential housing. Yes ours use direct heat exchangers
I don't know why, but I somehow assumed that you were getting traditional mini-splits as your transition. I had to replace my boiler system (in the US) because there were no heat-pump boiler replacements, only forced air. My conversion was from oil, common in the 1950s/60s when my house was built, but my house isn't serviced by gas, and domestic oil service is getting more expensive to maintain due to fewer vendors and higher fuel oil costs. It would have been nicer if I could have just dropped in a boiler replacement using heat pump technology.
Nope. In the UK the vast majority of heating systems are gas boilers, heating water which flows through radiators and the hot water tank. Some houses will have boiler a that heats water on demand, so no hot water tank.
Oil is only used if people are off grid (exteremly rare) and requires bulk deliveries once or twice a year.