The Temperature Sensor (thermistor) has been suggested as a possible cause of my boiler going off just after a normal ignition sequence.
It looks normal, physically. Can anyone tell me if it is a positive temperature coefficient (PTC) thermistor, Posistor, i.e. it's resistance increases with increasing temperature. Or a negative temperature coefficient (NTC) thermistor, i.e. it's resistance decreases with increasing temperature. On my Fluke multimeter it measures 1.1Mohms at room temperature!
Thanks for any help.

Tim, October 2007

at cut off (at 80c) it should be 75k ohm at cold 1000000ohm.

Hope you've fixed it by now.

Hugh Fixsen, October 2008

I think its an ntc 1300k I think is normal - more likely to be flame proving sensor or partial flue blockage

Colin, October 2007