DIY Doctor UK DIY Forums

have a worcester boiler .
problem is hot taps on all sinks work fine but the shower runs hot when adding a bit of cold to get temperature right for having a shower the boiler cuts out and starts running cold.i have two showers in the property and both do the same. what do you think is wrong. any help.

Is it a combi (instant hot water) boiler?

If so, what happens when you turn a cold tap on at the sink at the same time as the hot tap?

@ tidy

I'm assuming your boiler is a combi and that you are running a shower fed directly from the mains and boiler.

Sounds like a water pressure problem to me or possibly blocked inlet filters at the showers or boiler.

If you turn a hot tap on at a sink/basin and then turn the cold tap on at the same time, does the hot flow, slow dramatically? If it does, then you have low water pressure or the stop tap has been restricted for instance, giving a low flow volume- have you done any work lately requiring you to mess with the stop tap?

Failing it being a pressure problem, I'd check the water filters at the boiler/inlet to the shower.

has been ok for about 7years now but just started to get this problem.
this inlet filter on boiler .do you mean the heat exchanger. as a friend did say it might be that.
if so would this not make the hot taps the same as the shower.

I'm guessing that as you mention it cuts out when the cold water is used, that it is fine if just the hot water is used. It's probably a stretched or split diaphragm in the diverter, when another outlet is used there's not enough water flow to lift the diaphragm. Especially given the age of the boiler, what model Worcester?