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.

@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?

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.