DIY Doctor UK DIY Forums

we have Flexicom boiler with presumably gravity system. Hotwater sys works fine but when Heating switched on from progamer or room thermostat, it trips.so have kept heating off .3way actuator locked in manual posn so do get some heating to radiators during hot water times.
Two local guys came but could not identify the issue but all they attempted was to sell brand new combiboiler sys for abt 3.5k or so.
so please help as to what could be an issue Many thanks in anticipation.
cheers

When you say it trips, what trips, does the boiler lock out, or does a MCB or RCD or RCBO trip at the consumer unit?

If the latter would be looking at a motorised valve, as default i.e. no power to it is domestic hot water.

Thanks, it was motorised v/v, I presume. It was changed after blowing out 2 programmers, so third time lucky.