Central heating

[tamborine]

when the electric switch goes on for the gas ch system to fire up it blows the house electrics......any ideas what the problem is; and is it easily fixed?

[buildersmate]

In the first instance, usual suspect is the pump (goes short circuit to earth). Try isolating it (by temporarily removing the connections to it) and see if the MCB / fuse still trips.

[gucciman]

i'm guessing its an old style system rather than a modern combi type boiler, could be the pump but the last time i came across this problem it was actually the gas valve causing it.