Gas or electric boiler for flats?

If you have gas supply available then stick with gas. It’s unbeatable in terms of price, service, reliability. I assume this is a combi boiler and one each per flat. I see no reason for electric boiler.

I am a supporter of ASHP if you know what you are doing with them. Way too much I’ll informed opinion out there.

Hello,

Good luck with your build.

To overcome this uncertainty approach your trusted EPC assessor and obtain a projection with different systems. I always pay for such prior to renovations.
My choice as always is heat only boiler with cylinder with immersion. You have a back up then when the boiler fails. Or if your have a combi boiler ensure you have an electric shower as a back up with a heavy duty “shower bath” which are 6mm construction and reinforced bottom and stands. My shower of choice is Mira Sport, very reliable product I have tens of them but avoid the 10.5kw as they are sensitive to water pressure issues and will overheat and trip out easily. 7.5kw are far better in my opinion.

Reply to the comment left by at 08/12/2025 – 12:15
cheers for the info. I had thought about the issue if boiler goes down and worth having a separate elec shower.

I would add at least oversize your radiators by say 1/3rd as for the extra cost now it gives the ASHP option in the future

OP clearly ruled out ASHP and I can see why in this situation. If you’re building from new and want to protect for ASHP then water UFH in all rooms without radiators would in my view be a better choice. The space saving and efficiency and can cool in summer. Combi gas with UFH for 2 x 1 bed flats is the most efficient and also cheapest option. OP also didn’t mention if they were letting or selling after build completes. But if you have gas supply it’s unbeatable especially when they introduce hydrogen mix in the next decade. Electric boilers are a good compromise if you don’t want ASHP and have not access to gas. I find electric showers weak, pain the arse and still not efficient.