The boiler runs ok when on heating. If anyone uses the shower, the water runs cold and boiler goes to lock out. Have had new PCB & Wiring Harness fitted but problem still exists. Could this be a problem with the fan being heavy(Dirty) & not running at high speed?
If the fault only occurs when the shower is in use but ok when other hot taps are used then the problem points to the pipework to the shower or the shower itself...
