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