Dave Plowman (News) wrote:
In article ,
The Natural Philosopher 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.

It would then be a matter of finding out what the actual switching signal
consists of. I suppose it might be some form of digital multiplex - how
many wires go to this controller?

But no matter how oddball it would be *possible* to intercept this control
data and alter it.

Sure. Knock up a pic and some mains relays