When I turn on my hot water or central heating, my breaker trips?

its a BBU you have i assume then (Baxi Back Boiler, with a fire front) I would still be thinking its the gas valve or the external pump, both draw enough power to trip your fuse. If the zone valve has seized, it normally will just fail to operate. (ie, you call for hot water, but it still only heats ch)

T
June 2008

Thanks, had a bit of a chat with my neighbour who has the mirror house of mine with the same system and he's explained what he has. It's an old back boiler system. The Electric switch on my immersion to heat the water doesn't work, never has. So the only way to get hot water has been through the back boiler. There is a control panel to turn on the CH/Hot Water on the wall beside the gas fire. Any time I turn on either of them, the breaker trips straight away. I've done as much as I know how to do, checked fuses etc and these all appear to be fine. Am I on the right lines to think that the problem is either the pump or the diverter valve thingy (technical term). Cheers.

John M
June 2008

I assume you mean you have a gas combi boiler, that does your ch and dhw.....

if so, it does sound like the gas valve solenoids have shorted (gone faulty) and the gas valve may need replacing, sometimes in the worst cases that fault may have also taken out the pcb, so could be a double wammie....

T
June 2008

immersion heating only heats your hot water not your heating.
so try telling us what boiler, controls etc you have.

hi-spec plumbing & heating
June 2008