661-Pete wrote: ↑10 Nov 2021, 8:58am
But I'd dearly love to get away from gas - for the CH at the very least. So I asked him about heat-pumps. He said, yes, he does install them. But there are all sorts of hidden problems. The CH water comes at a considerably lower temperature than with a gas boiler. All the radiators would need replacing, he told us. And the house would have to be assessed for insulation standard. I know the windows are OK and the loft insulation could be added to if need be (although there's masses of junk in the loft that would have to be shifted).
The main problem is the cavity wall insulation. The house was built in the 1970s before insulation was enforced. We had the polystyrene-balls type of insulation retro-fitted many years ago, but apparently that's not good enough.
I think we may be stuck with gas for quite a while. Unless anyone has a better idea...
Those don't sound like hidden problems. They sound overt. I would also say that things like poor insulation are problems that need addressing with any heating system. Doing so will save you money and the planet carbon even with a fossil boiler.
The big problem, I guess, is that heat pumps are currently so expensive that the government grant is needed to make them competitive, and for that, government insists on everything else being up to spec too, to avoid too many "heat pumps wrecked my life" stories, although there are still plenty.
Things will change in March, with the next grants being a flat-rate yes-no as I understand it, rather than the current sliding scale prioritising larger homes and replacing oil more than gas.
In the above situation, I would probably go gas again, ideally one ready for conversion to something less harmful, and definitely with a weather compensation sensor. During its life, I would seek to sort out insulation and any other prep which can be done before a big switch to heat pumping.
pwa wrote: ↑10 Nov 2021, 9:12am
The problem is that an air source heat pump won't get the central heating water as hot as a gas boiler will. So if you just changed the boiler for an air source heat pump you would have a cold home. You will need more radiator surface, at the very least, and possibly significant insulation work. And some homes may not be suitable for that.
That is not quite true. Some heat pumps will get heating water (but not tank water) as hot as an older boiler did but performance will drop below 200% and the cost saving over gas will be gone. The carbon saving remains, of course.
There is some development of high water temperature heat pumps, which should in theory be possible because other countries have low air temperature ones, but I doubt they will become efficient enough to rival mainstream ones and so will be limited to special situations.