The incentive is just window dressing unfortunately.
I don't know how to find or assemble all the data or have time/desire to do it but I would say the vast majority of UK housing stock is miles away from being suitable for retrofit of a heat pump as a simple substitute for a gas boiler, so the idea that £5,000 will bridge the gap between a £2,500 boiler replacement and a £7,500 heat pump installation is just nonsense, on stilts. My 11kW heat pump and associated pre-plumbed 300 litre tank cost about £9,000 from memory, so at best the £5,000 will cover the extra cost only of the pump. That's the least of it.
I expect a heat pump to work for me because my, almost completed, new house won't actually need much heating of any kind. The heat loss should be less than a tenth of that of a 1980's house as built to the then prevailing standards.
My insulation is in the inner walls, not on them or in the cavity (I do have a 60mm cavity and brick/block cladding just like a traditional house). The ground floor has 90mm of Kingspan and 150mm of thermalite block under it.
We have no external vents other than the 2 roof terminals that the ventilation system connects to, the ventilation system that will provide better air exchange than passive vents and recovers 80% of the heat from the exhausted air. The heating of course is underfloor. The ventilation system only cost around £5,000 but to replicate it in an existing house you would have all the ground floor ceilings to make good - even assuming you could find a route for the ducting. Mine is 75mm radial stuff that passes easily between or across and through the metal web joists (which the 1980's or earlier house probably doesn't have).
It has cost a lot, I don't even know how much as I haven't added it up separately but I can't imagine what it would cost to retrofit to that 1980's house to achieve anywhere near similar running costs - chances are its piping and rads would be inadequate for heating the house properly with a heat pump even if the heat loss has been reduced by 1/2 since it was built.
The most effective way to achieve decent penetration of heat pumps would be to mandate them on new houses, or at least direct the incentive towards that.
The biggest payback on existing houses will come from insulating them properly. It would probably be possible to save at least 50% of fossil fuel use in a few years. What's needed is for the insulation to be rolled out like central heating in the 60's and 70's, and double glazing in the 70's and 80's. I'm sure the home improvement industry must be desperate for another racket.
Last edited by: Manatee on Wed 20 Oct 21 at 11:04
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