Andy Burns wrote:
The houses on this estate were built in 1973 with gas backboilers, mine
was replaced by a cast-iron boiler before I bought it. Several
neighbours have fitted a condensing combi, and had to replace tem
already, my lump soldiers on ...

approx 11,000 kWh/year of gas, which covers heating and hot water of a 3
bed semi, at 2.7p/kWh that's £311/year ... where's the sense in
replacing it?

This one suffered from being under a British Gas service plan, and hence
lots of sucking of teeth and 'ye cannae get the parts anymore', and
eventually they refused to cover it.

I don't know if you can actually get the parts these days, or whether
they're sufficiently pattern that you can find or fashion suitable
replacements.

I'm guessing you don't have the gravity hot water as described, though? It
sounds like that was a good reason to fit zone valves and controls on the
hot water, even if you kept the boiler.

Theo