Thermistor issue or measurement issue?

[imrichardcole]

I have two thermistors from the flow/return pipes of a British Gas 330 boiler (actually a Glow worm).

They came from a boiler that was failing to modulate and constantly ramping up, then turning off in an endless cycle.

I'd expect them to measure around 12k ohms at 25 degrees C, however they register as openline/infinity with a multimeter. What are the chances of both them failing?

Also, would them being knackered explain the ramping up/down symptoms?

Thanks in advance.

 

[ShaunCorbs]

Send me your gas safe card (pic front and back) also get your post count upto 10 plus please

We don’t talk about boilers in the open part of the forum