DIY Doctor UK DIY Forums

Does any body know what this could be ? I have just had my boiler serviced by BG and all was ok. However, now the hot water in the bathroom ( I live in a flat) runs alternately hot and cold ? the kicthen hot water tap is fine and so is the heating.

I would be grateful if anybody could explain why this would happen.

Sounds like the service engineer needs to be called back ;-- suspect a problem with the water-flow or pressure sensor which fires-up the boiler when the hot tap opens, or the water input valve to the combi is not opened fully, although sometimes a restricted input works better for nearby taps.
Try varying that input valve before recalling him.