RESISTANCE THERMISTOR RETURN

Isolate Mains Power to appliance as per TOPs P4

Set Multimeter to Resistance

Remove the air intake and flue manifolds
Remove return thermistor electrical connector

Measure for resistance across the exposed pins of the return thermistor.

Resistances vary with temperature and should conform approximately to the table below:

Note:
Clicking on the resistance table will switch between table and graph view.