Potterton boiler fault

[Mike]

I have a Potterton Netaheat 10-16 boiler about 15 years old. Radiators not getting hot enough, so checked pump. all ok there. Output from boiler not as hot as usual. Noticed only pilot light on inside.

Don't recall there being a pilot light before but may be wrong. It's electronic ignition.

So, fan runs to reduce case pressure, ignition sparks and lights pilot light. Sometimes main burner ignites a second later but sometimes pilot stays on. Some time later hear another spark and main burner lights.

Could not hear click from thermostat and setting to max made no difference so have changed it but still have same fault. Cleaned burner and sparker etc.

Sometimes house is cold and then as tonight it's hot !!

Suspect now the pilot injector or the main gas valve.

Any help would be appreciated.

Thanks, Mike

[Peter Andrews]

Had a similar fault with my Netaheat last week. The fan pressurises the boiler by the way. When the pilot light comes on, the circuit board should detect the flame and turn on the gas valve. There should be 230v across T1 and T3 about 5 seconds after pilot light comes on.

I fitted a replacement PCB from

no connection with them, but had seen them mentioned on this group, one phone call and a replacement arrived the following morning, cost including sending old unit back