Hi
I have had the same problem, i could only get hot water when the heating was on, we called a plumber who fitted a diverter, when that was fitted i had no hot water at all, so then he replaced the gas valve, now you have to turn the hot tap fully on to get the boiler to spark up but the water is only luke warm anyone know what the problem can be now

kim, June 2009

He fitted a diverter and that didn't help? Hmm.

Okay. Does the hot water demand light come on when you open a tap? If not, then assuming he DID fit a diverter and isn't yanking your chain, then we could be looking at a problem with either the microswitch (when water flows though that diverter, it pushes out a plunger which hits a switch that tells the boiler to fire), or the wiring harness or PCB.

If the light DOES come on, then something more sinister is at work. That tells me the diverter is working correctly, and that the switch is making contact, it's just that the boiler is choosing not to fire for whatever reason. This could be sensor-related or it could be a pcb problem.

Does it fire OK for heating?

Let me know what happens with the light and I will try and make some sense of it for you.

Bunslinger, June 2009