#ClimateDiary We are in intense #Heatpump vs new boiler discussions in our household at the moment, and it is quite something how geopolitics and radiators (and other practicalities like: will the humming be loud?) all swirl through my head at once.
(Our house is old, terraced and high ceilings - it looks like it’s not impossible but challenging. Costs come into it too, of course. Also worried on this front: might geopolitics mean i will not earn any money next few years?)
Narrator: And as the days passed, the seasons turning, year after year, the old house became more and more aware that yes, the humming was loud.
(Yes, I've repeatedly heard people complain about the noise and no I haven't had enough experience with this personally or insight into how this can change from manufacturer to manufacturer)
@folfdk I can offer some insights: There are different designs. It depends on where the loud part of the heat pump system is. The loud part might be inside the building hidden in a well-insulated cellar, or outside on the front yard, or worst case on the side in the narrow gap between the buildings facing the neighbour's bedroom window.
Air heat pump consists of among other parts of a compressor (like in refrigerators or air conditioners) that makes deep, annoying humming noises, and a heat exchange (a ventilator pulling outside air over some pipes) that make a ventilator sound, so much softer, not deep humming.
One architecture of air heat pumps is to have one integrated box of machinery outside, and to pump the water that is used for heating (in floor heating or radiators) from the inside of the building out to the heat pump, where everything happens, and the warmer water back inside.
The other architecture is to have only the heat exchange outside (because it needs open air) and the compressor inside the building. The water used for heating goes only to/from the compressor unit, and between the compressor and the heat exchange outside there's a second cycle with a different liquid.
The first architecture ("monobloc") is cheaper but much louder for the surroundings.
The second architecture ("split") is more expensive but much quieter outside.
@pvonhellermannn
@pvonhellermannn do you know about https://www.visitaheatpump.com/
We got a heat pump at the end of last summer
Mostly it is quieter than our old gas boiler which had a tendency to vibrate a bit
It sits right by our lounge window, below our bedroom window.
You can hear it if the TV is off and people are being quiet.
During the very cold snap (below freezing) when it was coming on at 4am for cheap rate - it did occasionally wake me up for a minute.
2 new radiators - the rest are from 1980.
@pvonhellermannn oh and I live in a *very* quiet area
Where I used to live in London I would never have been able to hear it over the traffic noise.
Even now it is still quieter than next doors diesel car starting up in the morning.
Not to say people don't ever get annoyed by the noise of heat pumps - just that it's interesting what people do and don't get annoyed by.
@sean @pvonhellermannn One rad upgrade. Heat pump external unit can only be heard if standing right next to it or listening very carefully with a window open and everything else outside is quiet. Lack of rad pipes clanking is the biggest noise reduction over the gas combi!
@pvonhellermannn @sean Including bonus live updates towards the end of the page today while the system is getting #annual #maintenace...
Living on the edge!
As I recall, you live in Eastbourne??
If so, then it may be possible to have aquathermic heating, which is a LOT more efficient than air-air heatpumps.
We switched from gas ~5yrs ago and it reduced our KWh consumption to 1/4 of before ... + our old house is now at ~20.5°c for 24hrs a day throughout the winter. No more chilly mornings.
If it's of interest, I'd be v.happy to fill you in on all I know on the subject. 🙂
OK some of the criteria that persuaded us to go this route:
• Aquathermic is the most energy efficient currently available
• We have an old house with wrought iron radiators, which are ideal for 'slow heating'
• We have a large enough garden, to enable an extraction drill hole and a return drill hole, which under French law, must be 10m apart with the return hole 'down hill'. Maybe different under UK law?
• You must have workable access for the drilling machines
• Cost … we were elligible for a subsidy which was great, but I looked at it simply as a financial investment, like shares. I estimated that we would recover our investment over 8 years, but what’s important to take into account here, is that after the 8 years, you continue, every single year, to gain the same return on your investment. Our case was slightly blown apart by Covid, in which energy prices exploded somewhat.
... but our aquathermic, which consumes only electricity, wasn’t so affected. Either way though, our savings relative to our previous gas heating, became pretty huge, so much so, that we’ve pretty much recovered the initial investment, plus of course, with a brain dead psychopath as US president, we’re set to increase our gains. (NB, our gas still worked fine. This was about renewables and climate change).
• We went with a German make of heat-exchanger, Vaillant, which we’re very pleased with. You do need a fair bit of space for it though, which for us was ok, as we have a basement. If geo/aqua thermic are 'no go' for you and you’re still considering air-air, then they may be good for that too, notably they talk of very low-noise levels. I should add that I researched and chose the heat exchanger.. then asked them to recommend a company in my region.
https://www.vaillant.co.uk/product-systems/heat-pumps/flexotherm/
@pvonhellermannn we had this discussion as well.
Current heatpumps are much quieter than old ones.
We are getting an indoor version. It is the size of a fridge. Outdoors will just be the air ventilation.
I believe it will be as loud as a fridge.
Now our neighbours are fine with it.
(We are in an apartment building so had to ask hoa for permission)
There are also split heatpumps which will also reduce noise on the outside.
All the best for finding a good solution for your house!
@pvonhellermannn I got one last August. It works well and it's quiet. Needs more room than boiler, and because electricity cost is excessive (due to gas setting the price point) heating bills have stayed about the same.
If you already have solar panels this will help the economics of it substantially, even more so if you have solar + battery. I do not, that's next on my list
@http_error_418 @pvonhellermannn we're doing quite well on the Octopus Cosy Tariff
It's a bit hard to work out costs - I made a start on number crunching but so far I just have a bunch of daily figures based on how much power was used at what time of day and how efficient the heat pump was running.
Today I have had heat at 4.4p per Kwh
gas at 6p per kwH * 85% efficiency would be 7p
During colder times the heat pump has been less efficient but I think overall it's been cheaper.
@pvonhellermannn I think the anxiety about heat pump noise is very much driven by the fossil fuel lobby
Have you ever heard anyone complain about the noise of air conditioning ?
(air conditioners and heat pumps are the same thing just used in different ways)
This isn't to say I can promise nobody will ever complain about the noise - sounds can trigger very emotional reactions
But it isn't actually about them being loud.
@sean @pvonhellermannn Yes, that's my thought too. It does make some noise, but so did the air conditioner it replaced.
In my climate, the savings are substantial in the summer, and it's about equal to gas heat during the coldest months. This may change going forward!
@bencourtice @pvonhellermannn @ClimateJenny in the UK domestic Aircon is very unusual
In order to encourage transition from gas boilers to heat pumps the government is offering a subsidy which only applies to heat pumps that heat via radiators
They don't offer cooling
You can get air to air systems here which offer both heating and cooling - you just can't get the subsidy for them
@pvonhellermannn from the Politico heat-pump article I posted earlier
"I later discovered the company Warmur*, who provide a survey service that charges one upfront fee, but allow multiple installers to provide quotes based on the same report. It's the first of many things I wish I’d known earlier."
@sean @bencourtice @pvonhellermannn @ClimateJenny
As of November 2025 the UK government offers £2,500 grant for Air to Air Source Heat Pumps (which can do cooling). Also Heat batteries come under the same scheme
https://www.gov.uk/government/news/discounts-for-families-to-keep-warm-in-winter-and-cool-in-summer
@michaelokarimia @bencourtice @pvonhellermannn @ClimateJenny
Interesting - sounds like it isn't available just yet though
https://renewableheatinghub.co.uk/air-to-air-heat-pump-bus-grant-explained/
Ukraine, Putin, Iran, Trump...
I'm very happy to be on British renewables :-)
Cheaper and less bloody
Can you not also have a hot tank with an immersion heater for the last little bit of heat-boosting? Or does that kind of system intrinsically not have a tank?
@adamgreenfield @pvonhellermannn mine heats to 55C vs 60C for the gas boiler
60C is painfully hot and always gets mixed down - in fact if you have a mixer tap you wont notice.
So the only real impact is that you need a slightly bigger water tank to store the slightly diluted hot water (if you see what I mean)
We have a legacy solar diverter that sends "excess" solar to the immersion and that does go to 60C on sunny days - I only notice when I'm hand washing dishes and it gets too hot.
@pvonhellermannn
On heat loss calcs, they are critical to comfort and efficiency. You don't want too big or too small. Our neighbours were offered too big a pump because installer hadn't correct size in stock.
Older terrace, you might need better insulation - it will work OK without but would use less energy and reduce running costs (but up front will cost - go for 'low hanging, cheap fruit' first).
I don't have Mark's practical experience, but liked watching 'Heat Geek' explainers on YouTube.
Also, someone was telling me underspecification or bad installation by contractors is a big problem in social housing and a reason why some people are heat-pump-sceptical.
@pvonhellermannn
Also
Skill Builder is a tradesman.who produces self help media but is also helpful in being a constructive questioned of HP versus gas.
There's loads to overfill your brain but a read around this might be helpful (hopefully)
Nb - Earth Notes (in Yr feed) is definitely worth a follow.
@pvonhellermannn I’m in the US, so this may not be relevant as I don’t know the differences between how they’re done there. Here, we get temperatures above 115f regularly, and freezes a few times, so it had to be more robust on the cooling than the heating. There’s a unit about the size of a fridge in my attic, and an outdoor unit. The attic I never hear, the outdoor I hear occasionally when it’s kicking on or off and decompressing or whatever magic it’s doing.
Big, old, drafty house with high ceilings. Dropped our winter bills by 50%, and about 30% on summer. (Last summer was brutal.)
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