I was going to add this to the Boiler Upgrade Scheme funding reduced by circa £750 million in 2026 budget thread, which is showing some signs of morphing into a why don't people choose heat pumps thread, but decided the topic is better off in a thread of its own.

The scale of the problem

One of the first things I learnt about assessing medical research is always to check the sources for statements made. Academic literature makes heavy use of references to back up statements made in a paper, and yet it is surprising how often the reference fails to back up the statement made. This problem applies even more to 'market research' and 'industry insight' papers where statements of apparent fact float around like Wordsworth's lonely clouds, bereft of any grounding in solid fact. One such lonely cloud is the current annual number of fossil fuel boilers installed in the UK. A number around 1.7 million crops up all over the place, but none of the references or sources that I have found substantiate this number. Google's 'AI' efforts on this question are spectacularly pathetic, even by its own poor standards:

The first 'source' is an undated (maybe around 2023/24) British Gas marketing plug that incidentally drops in a statement that 'up to 1.7 million domestic-scale natural gas boilers are installed in the UK every year' without anything to back up that 'up to' number. Unsubstantiated tosh, binned.

The second 'source' is a Johnson government October 2021 policy paper on its Heat and Building Strategy. Note the date, because of pandemic effects. Two thirds of the way down a long page the policy paper asserts that 'Currently 1.7 million fossil fuel boilers are installed per year (natural gas, oil and coal). [footnote 396]' Unfortunately, footnote 396 no longer exists, if indeed it ever existed. The wayback machine (see note at bottom of page for link) does have archived pages for the relevant period, mid 2021, but they do not appear to contain any actual market research, let alone substantiated numbers. Instead there is a graphic:

which sort of sums it up. Unsubstantiated tosh, binned. Nonetheless, it is possible, but not proven, that this was the 'source' for the British Gas number.

The third 'source' is 'Written evidence [to a select committee?]submitted by Energy & Utilities Alliance (EUA) (WFP0062)' The EUA, we are told, 'provides a leading industry voice helping shape the future policy direction within the sector. Using its wealth of expertise and over 100 years of experience, it acts to further the best interests of its members and the wider community in working towards a sustainable, energy secure and efficient future'. Really? It goes on to assert that 'In 2024, just under 1.5 million natural gas boilers were installed into homes with around 90,000 heat pumps installed in comparison'. Note the heat pump number, we shall come back to that. However, for now, no source is given for either number. Unsubstantiated tosh, binned.

All that we have established so far is that google AI doesn't have a leg to stand on when it comes to evidence. It just churns out tosh. However, buried within [footnote 396] there is a glimmer of hope shining though the clouds: a named organisation, and a general indication that it does market analysis: 'BSRIA (2020), Domestic Boiler Market Analysis – United Kingdom'. And indeed they do, but at £1,410 for the latest report for a single country, I won't be getting that report anytime soon:

BSRIA (Building Services Research and Intelligence Association) does have a News Page and Archive, but none of the available press releases contains anything about the number of boilers installed in the UK in recent years.

In the interests of thoroughness, I did a more forensic analysis on the wayback machine, and still drew a blank: the earliest BSRIA heating market reports available are from 2025, long after the Johnson government's paper was published:

The bottom line appears to be there is nothing in the public domain to substantiate the often quoted 1.7 million annual (domestic?) boilers installed in the UK number. The best that we can hope for is that the goons who wrote Johnson government's policy paper (a) splashed out and got the then current, now at least several years out of date, BSRIA report (b) bothered to read and just as importantly critically appraise the report and (c) had reasonable grounds for believing the 1.7 million number they quoted (d) it wasn't a number distorted by pandemic effects and (e) it still applies today. Quite a lot to wish for...but at the same time, maybe it is the best we have? Who knows?

In passing: possible evidence that google AI just makes things up: I did a search for an organisation called the Heating and Hotwater Industry Council (HHIC) which may or may not publish domestic boiler installation stats. Google AI thinks it does:

See the first entry in the box on the right: a press release date 3 Sept 2026 on the number of gas boilers sold in the UK last year which 'saw the market grow...' but tantalisingly failed to show the numbers. However that press release does not exist. It is not on the HHIC press release page, instead, it looks very like google AI made it up. When you click on the three dots by the link you get this:

The reference has disappeared, and another, which does exist, and is intriguingly about 'zombie boilers', appears in it's place. But the giveaway is a bit further down, where it says 'This result is generated by AI to be relevant to your search'. If that doesn't mean made up, I don't know what does.

If the fossil fuel boiler numbers are but clouds in the sky, then we are at least on somewhat firmer ground with the heat pump numbers, thanks to the government grants. These numbers by definition exclude non-grant aided installations — anybody care to guess how many there are of them? — but the grant numbers are at least reasonably solid. There is still an element of smoke and mirrors in play, with folks wont to quite the number of applications (which is in fact a measure of heat pump aspirations) rather than the number of grants paid, which better reflects the numbers installed. The latest (published on 29 October 2026, link will go out of date when the next lot are published, but should get you near enough) available statistics (England and Wales only, not all UK) show in Table M1.1, that in the year to September 2026, 32,096 air to water heat pump redemptions were paid (and 32,780 redemptions applications were received). This is rather less than the 90,000 suggested by the EUA (mentioned above) which most likely mistook aspirations for installations. It also got confused over geography, making it unclear whether its aspirations number is for the whole UK, or just England and Wales.  

The numbers for the UK as a whole ie including Scotland and Northern Ireland for air to water heat pumps, based on MCS certified retrofits (excludes new builds and non-MCS certified, which most likely means non-grant aided installations), are equally depressing. Last year, in 2025, 52,940 air to water heat pumps were installed in the UK, but numbers in 2026 appear to have fallen. In the first two quarters, 20,705 air to water heat pumps were installed, giving an annual number of 41,410 heat pumps installed, if installations continue at the same rate during the last two quarters of 2026.

The scale of the problem? For the UK, something like 1.7 million (or whatever) boilers vs something like 42 thousand heat pumps. It looks like this:

Now some of those 1.7 million boilers with be so called so-called distress purchases. Personally I don't like the phrase 'distress purchase', it conjures up images of a 'boiler victim', or in modern parlance, a 'person living with boiler failure'. But the key point is that the 'official stats', such as they are, for distress purchases include both those truly living with boiler failure, as well as those who are aware that at some point in the future they too are likely to find themselves living with boiler failure. The distinction is important, because the first group, those already living with boiler failure, are likely to find themselves rushed into a panic purchase (the term I prefer) because of the urgency of the situation, while those in the second group, soon to be living with boiler failure, do at least have some time, be it maybe days or much more likely weeks or months, to consider their options — and one of those options is to replace their fossil fuel boiler with a heat pump.

At a rough estimate, around 30% (see the other post for details on how this number is arrived at) of all heating system replacements are true panic purchases (living with boiler failure purchases). That leaves 70% that are not panic purchases, where the occupier does in most if not all cases have time to consider their options. We can redraw the pie chart to show that proportion and the numbers: 

That is around 120,000 occupiers per year who have at least some, and possibly quite a lot, of time to consider the option of installing a heat pump, but who in the event decide to stay with a fossil fuel boiler. Putting it another way, only around one in thirty of those in a position to consider a heat pump actually go on to install one. That is the true scale of the problem.

The next obvious question is why do people overwhelmingly choose to stay with a fossil fuel boiler? I rather suspect the answer may lie as much as if not more in psychology as it does in economics.

Edited repeatedly to fix the broken BSRIA wayback machine link, but failed, again and again. The url is

https//web.archive.org/web/20210629095802/https//www.bsria.com/uk/

You need to manually add the two missing colons between https and //