Heating but no hot water

[Gnomecalleddave]

Hi All

I have a Combi Boiler that's playing up. Modulator board went pop so I've replaced it but now the hot water won't work unless you remove one of the wires from the temperature sensor. The central heating works just fine.

If I run the hot tap the boiler fires up as usual but then switches off 10 seconds or so. If I remove a wire from the temp sensor the boiler fires up and will stay on and give me hot water.

I can't work out what's wrong?

Has anyone come across this before?

Thanks.

 

[Agile]

Telling us the make and model might help!

Is it an old Ideal?

Tony

 

[Gnomecalleddave]

Hi Tony

Sorry. It's a Potterton Combi 80.

Someone has said it's the heat exchanger (and as they're expensive to replace I may as well have a new boiler installed...) but surely I'd be getting no hot water at all if it was that? If I remove a wire from the temp sensor the boiler fires up as normal and stays on giving me plenty of hot water. I've also replaced the temp sensor so it's not that either. Could it simply be that the new mod board is faulty?

 

[picasso]

I am not sure if this would be classed as gas advice, if it is I am sure the mods will delete it, disconnect one of the wires going the the modulator coil on the gas valve, if the flame does not modulate down the coil if faulty.