Radiators not heating.

[bri burgess]

Hi. I hope some one can help. I have a condensing oil burner and it runs fine but the radiators don't heat. Heats the hot water fine. The pump runs and the thermostat turns the boiler on and off.
Thinking it could be a thermistor.
All help greatly appreciated.

 

[oz-plumber]

I would be checking the pump.
Undo the bleed screw on the pump and see if you can stop the spindle with a screwdriver.
If it is slow or you can stop it easily, then the capacitor is stuffed.
Replace capacitor or pump.