Dave Baker wrote:
The electrickery bits of central heating are absolutely not my thing but I
can't see why, with any boiler, you can't have an external controller
driving the zone valves and stats which produces a single output to the
boiler telling it when to switch on.

You can.

If the boiler has a way of accepting such input.

This one does not.

Its completely integrated and comoputerised, and the only thing apart
from the mains that it takes, is a 'smart' room stat made by the
manufacturer ONLY.


Even if you had to set the boiler to be
on 24/7 with its own controls it would still only fire up when it got a stat
signal saying the temperature was low enough. If the external controller
sends this signal rather than having the stat itself wired directly to the
boiler why wouldn't it work?

If the whole boiler is off, then no hot water either..


Maybe I'm missing something obvious but as I say, I really don't do
electrics.

Its highly UN-obvious. Thats someone has finally produced the plumbers
dream and the DIY-ers nightmare. A boiler that doesn't need any
electrical installation, beyond hooking up to a switched fused spur and
turning it 'on'..