Baxi 35/60 Pump Fault

[GJ7]

I've recently had a fault on my Baxi System 35/60 boiler, where the flame failure LED was illuminated. There was also smell of burning from the boiler. On closer inspection I found the PCB was badly burnt on the back where what looks to be a relay is located.

The part number for the PCB was 248074 but now replaced by 5112380. I purchased this replacement part and fitted to the boiler. Now when the boiler is turned on the pump starts running for a few seconds then stops for a few more, then restarts but the 60 degree `fault on pump or low pressure` LED starts to flash.

The pressure is fine and the push rod on the differential valve is operating the switch, which tests fine back to the PCB.

Is there any other possible causes other than still a PCB fault?

 

[D_Hailsham]

There is a fault finding section in the installation manual at http://www.partsarena.co.uk/baxi/

 

[baxpoti]

Have you opened the air vent on top of the pump?

Was the board brand new, or re-con?

 

[GJ7]

The PCB was supposedly brand new, but bought from eBay.

Not sure about the air vent, there is a small threaded piece at the back top of the pump that appears not to be screwed in correctly, but this has never been touched.

 

[gaspro1981]

i assume the pump is working if the primary flow switch is operating and if the mircro switches are sound as you say
have you checked the pressure/flow switch for correct operation

 

[GJ7]

No, have not checked the pressure/flow switch for operation, where will it be located?

Been experimenting with the boiler and got it firing up by a unconventional method. If I unplug the differential valve micro switch before turning on the boiler, once powered up, the pump fault does not come on (although neither does the burner). But if I then plug the micro switch back in live, then the boiler fires up and begins to work, if the boiler then is switched off and on again, it reverts back to the pump fault.