combi boiler

[samjit]

I have a Vokera combi boiler,when the switch is set to summer and tap is opened I cannot get hot water,
however if switch is set to constant and room thermostat is turned up ie calling for heat to radiators,then hot water will work.
Does anyone know what the problem with the boiler is
thanks.

[gasman]

Probably a worn diaprham to the hot water side if you have not had it regulary serviced every twelve months then do so now get an engineer to fit a service pack to the boiler this includes new diagphrams it will be sorted.