Boiler goes off when Hot tap turned on Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[tdkm]

A Biasi combi boiler central heating works fine but no DHW as soon as hot tap is turned on boiler goes out

[waynetheplumber]

sounds like a thermistor sort of problem as its obviously sensing the demand for DHW at the flow switch otherwise she wouldnt change over from heating to DHW.

your best bet is to get a heating engineer to take a look.

[waynetheplumber]

if the boiler is on central heating mode then you turn the tap on, if the boiler tries to switch over from heating to hw, then its a thermistor problem or if you dont have the central heating on and you try turning your tap on and it doesnt work then it sounds more like your diverter valve diaphragm.

[tdkm]

thanks wayne the plumber - will give that a go