Why is my Combi boiler heating radiators when the central heating function is not on?

Question

British Gas have advised me that I need to have my system Powerflushed

which I think is where they flush the system. How does this fix the

radiators coming on when the hot water runs? If a system becomes scaled up how does this cause the radiators to heat up?

Answer 1

I don't know anything about how Brits do plumbing, but here in The US the hot water (potable) is NEVER connected to the heating system. Could it be that someone tried to find a cheap way to run a hot water line by using the heating system pipes?

Answer 2

Careful, power flushing is expensive.  If your heating is coming on when you have not programmed it to come on then it could be a faulty valve (the thing that tells the programmer to turn it on or off).  I would call out a plumber who deals with central heating to check it all out.  Power flushing doesn't sound like it will fix the problem.  Although our boiler is not a combi we had the same problem earlier this year and it was the valve.  Did not cost that much to have replaced.