MY combi bolier a Potterton 80e, ignites as when there is no demand for it. No hot water taps on, CH switch in off postion, room thermostat turned right down and the radiators get hot and then a fter a while the lockout light illuminates and flame light goes out. After to switch the bolier off to stop it

Any help please much appreciated

Phil, September 2008

Have recived and fitted the microswitch and now the boiler works fine . Thanks to all especially Ian for your help.

Thanks
Phil

Phil, September 2008

Thanks Ian for the part number of the microswitch and have ordered it and will let you know of the outcome.

Thanks
Phil

Phil, September 2008

Hi Phil,

The microswitch is a common part to buy on its own any decent heating spares company should know what it is without part numbers. I looked on keeptheheaton site and they sell a microswitch, this may be the same one.

Potterton 21/18677 Microswitch
Microswitch (289-543) 21-18677

Price: £10.55 (Excluding: VAT at 17.5%)

To fit it you screw it in until it clicks then unscrew it back out until it clicks off then unscrew one further turn, check the operation by turning the hot tap on and off, the microswitch should click on and off.
The only other problem you might have is that the pin on the diaphragm unit may be stuck out holding the microswitch in the on position.

Ian, September 2008

Thanks for advice everyone. Disconnected a wire from the the microswitch which is on the DHw flow switch and then switched on boiler and the bolier failed to light. I have a part number for the flow switch but no number for the microswitch. DId look on it and could not see one.

Any help on this please or does it come with the flow switch. It is Potterton Puma 80e

Thanks for all your help

Phil

Phil, September 2008

Hi Phil

Just noticed your other question, if the hot water microswitch sticks on, the boiler fires up but as there is no flow of water through the boiler to the hot taps the boiler gets hot fairly quickly the diverter is set in the central heating position so the pump sends the heat into the radiators.
If you put power to the boiler and it fires up when there are no hot taps running and the heating is switched off it is very likely that the microswitch is the problem. If you take one wire off the microswitch and power the boiler back up if it does not fire up this will confirm it is faulty.

Ian, September 2008

Hi Ian,

Thanks for your reply. I will check your suggestion out. But would that microswitch also be for the CH as the radiators get hot and no demand from any hot water tap, and the CH switch on the bolier in the off position and the themostat turn right down in the living room.

Thanks
Phil

Phil, September 2008

i agree micro switch getting stuck keeping boiler on, replace microswitch

baxi man, September 2008

Hi Phil

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.

Ian, September 2008