Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!
Why are ASHP installs so expensive?
I have a very bog standard 1970s detached house with cavity wall insulation and double glazing put in 20+ years ago. The radiators were "oversized", as was the style at the time, and we added loft insulation relatively cheaply to qualify for the BUS grant. We had an ancient non-condensing boiler that was so old the brand on the cover wore out and there was no obvious indication of who made it or when it was installed. There must be millions of homes out there just like mine. The heat pump design temperature was 50C, but in reality it barely went above 45, only on the very coldest weeks when the outside temp went below -6C. We didn't need to replace any radiators, although we did in the end so that we could run the system cooler (it's now around 35C).
I think if you were a "cheap" heat pump company, you could put leaflets through every door on a 1970s estate offering to replace old boilers with a heat pump for the same price of a new gas boiler after BUS grants. You would put the same 5kW - 10kW system in every house on the estate, like for like, with no radiator swaps and minimal disruption, all done in 1-2 days. If there are any "tricky" houses that don't have cavity wall insulation or have 15mm pipes or whatever, you just don't reply and move on. Only do the ones where the situation is simple enough to install without doing loads of work.
I'm not saying this is the ideal gold standard for heat pump installs, but it would at least things on a par with the gas boiler industry. The problem, as we see with Heat Geek, is that the ideal gold standard for heat pump installs cost 5x what a gas boiler would cost. If you could keep it to £2k after grants by working on standard sizes and simple properties, you'd sell a lot more heat pumps.
ASHP: Mitsubishi Ecodan 8.5kW
PV: 5.2kWp
Battery: 8.2kWh
@scrchngwsl Absolutely, productize and simplify. Quality and volume would go up, costs would go down, any plumber could do it given a change in the regs to remove the MCS monopoly so the workforce problem is solved. It needs some production engineering but its clearly do-able. The challenge is, does anyone want to set up to do it?
4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.
Post by: @scrchngwsl
I have a very bog standard 1970s detached house with cavity wall insulation and double glazing put in 20+ years ago. The radiators were "oversized", as was the style at the time,
That sounds very familiar. I too have a 1970s detached which now has all the insulation upgrades that I could reasonably do. It still has the original radiators, which I worked out have an output at 70C (and 20C room temp) of 12.5kW. This is now well "over-sized" compared to the heat loss of the house, which is between 6kW and 6.5kW. However, out of interest, I also worked out the heat loss for how it was when the house was built, no cavity wall insulation, single glazing, and at best 50mm of loft insulation. Turns out the heat loss was about 12kW then, so the radiators were pretty much right-sized at that point. That also matches our experience when we first moved in of having to use the gas fire to supplement the gas CH on really cold days. The boiler was about 28kW, but the radiators couldn't deliver that amount of heat.
Completely agree with the productize and simplify approach. It's not that far removed from what Octopus are trying to do. To quote Octopus' PR:
"A typical gas boiler installation in 2026 costs around £3,000. Since Octopus launched its boiler equivalent offer (minimal disruption to existing home infrastructure), 59% of installations cost £3,000 or less, after taking into account the Boiler Upgrade Scheme".
I wonder what Octopus would do with prices and installation simplifications if the BUS grant was cut or even removed completely.
Posted by: @rob-of-york
I wonder what Octopus would do with prices and installation simplifications if the BUS grant was cut or even removed completely.
The whole system seems to work on the basis of making it attractive enough to jump to a heat pump because the additional cost is viable for many people.
Yes, we may see some softening of installation prices were the BUS removed, but I doubt it would be much. Corners would need to be cut, and probably severely. It could become a real race to the bottom.
Trouble is, it would price a significant percentage of potential customer from the market and the installation companies would suffer. Solar FIT all over again - I remember writing to my MP about the stupidity of removing that grant - the one and only time I bothered to write to an MP!
Ironically, our BUS grant was approved today .... happy days !
Escaped to the country : central Devon - 280 sqm converted mill - 4KW Solar - 15 KWh Battery - UFH - Vaillant Arotherm V2 Plus 12KW (soon!)
- 27 Forums
- 2,816 Topics
- 66.7 K Posts
- 1,645 Online
- 7,230 Members
Join Us!
Installer Finder
Degrees of Separation
Latest Posts
-
Should I change my cylinder when changing from a gas boiler to a heat pump.
I have 178 L Gledhill unvented cylinder which was fitte...
By David , 5 hours ago
-
RE: Plug and play solar. Thoughts?
Impressions so far from the one I've installed are that...
By EtchedPixels , 7 hours ago
-
-
@batpred The Daikin temperature probe protrudes from th...
By Toodles , 10 hours ago
-
RE: Air source heat pump roll call – what heat pump brand and model do you have?
@editor And as an occasional contributor, may I say wel...
By Toodles , 12 hours ago
-
RE: Should Households Who Can Afford It Pay More for Energy to Help Those Who Can't?
They don't have to try. Our entire system is d...
By EtchedPixels , 13 hours ago
-
RE: Why don't people choose heat pumps?
Fair enough. I guess I was thinking of pipes that run ...
By JamesPa , 13 hours ago
-
RE: How Can I Prove Coal Was My Main Heating Source Without Receipts?
Got excepted for the grant now so thanks for the replie...
By Chilli304 , 17 hours ago
-
Daikin Altherma 3 R F+W, room thermostat control, weath...
By JanHarley , 18 hours ago
-
RE: Buffer tank on a 2 x 14kw Ecodan system
Pretty much as I had guessed in my crude scaling from m...
By JamesPa , 21 hours ago
-
RE: Help me keep the faith with my air source heat pump installation
Well you have a vibration generator running at some fre...
By bobflux , 1 day ago
-
RE: Who's your electricity provider and what's your tariff?
@downfield Thats a decent rate, I’m shocked they hadn...
By Papahuhu , 2 days ago
-
RE: Adventures in heat loss calculations
@toodles thanks! So as suspected, around a doubling of ...
By SusannaSaunders , 3 days ago
-
Six books in three years and I think I’ve now covered j...
By Mars , 3 days ago





