how can i fix my potterton puma80 combi boiler ?

Hi John,

The problem may be a faulty microswitch which turns the boiler on when you run a hot tap. This is situated behind the circuit board around the middle of the boiler. It is a white plastic switch with 2 wires connected to it and is screwed into a circular brass unit which houses the hot water flow diaphragm.
The problems with this switch is that they stick, water gets in them from the brass unit, or they are not adjusted properly. To check the switch run a hot tap, a red light should illuminate on the circuit board, when you turn the tap off the red light should go out and the boiler should stop. Check the manual on how to replace the switch as it has to be set up properly.

Ian
September 2008