new house new combi boiler

unclebulgaria

rogerblack wrote: »

The cited document in that post.
Several combis were found not to be cheaper.

I totally agree with the document.
What I'm saying is, in the real world heating a large body of water to a certain level and keeping it there is surely more expensive (even if only a little).
When in space heating mode there can't be any difference in efficiency.
But hot water mode is different matter. I haven't met anyone who has a hot water cylinder set up so perfectly it beats a combi and I've got a few tight Accountants as customers who count every penny to back me up.
The only thing that they will never improve with a combi is the appliance kicking in when a hot tap is opened for a very short run which wastes that initial lighting. IMO