Hi... I have a Baxi eco80 combi boiler which has been working fine until a couple of months ago. What is happening is that when the CH is turned on the boiler fires for a couple of seconds then stops firing, it then starts up again and once again stops after about 5 seconds. This sequence seems to repeat itself with the time between starting and stopping increasing until it runs continuously. Then when the correct temperature has been reached the boiler switches itself off again. Upon restarting it tries a couple of times and then the centre fault light comes on & the unit needs re-setting. In hot water mode it does exactly the same thing only without tripping the boiler out. It has had a new gas valve, a new burner flame sensor and a new PCB all fitted recently and none of them solved the problem.Any ideas anybody as the plumbing firm is scratching it's head & I am not getting anywhere with them

Ian Reid, March 2009

Ian Reid

If you have a spare pcb for the baxi 80eco then I might take it off your hands. let me know cheers

azotic, July 2009

Problem solved !! I changed the temp sensor on the C/H and also changed the vacuum switch and the HW diaphragm whilst I was at it. None of these made any difference. However when I was at the plumbers merchants I got chatting to a plumber who agreed to come round & have a look at the problem. It turns out that the guys who fitted the gas valve had not set up the min/max pressures and the min pressure was set to nearly zero. Two minutes with a screwdriver & all is now well. I'm not actually sure what bit caused the fault originally, although this new plumber seems to think it might have been either the the CH temp sensor or the vacuum switch. Thanks for all the answers.

Ian, March 2009

hi ian had similer problem solved by the temprature sensor located on the left side of the unit just above the safety thermerstat (the one with red button on it )on a 22mm pipe try that only about a tenner

colin, March 2009

Nick,
Excuse my ignorance but do you mean the DHW and CH pressure switches?

As an aside, we have just had the temperature sensor changed and it has made litte difference.

Look forward to your reply.

Ian, March 2009

I had a similar problem a year ago and it was down to the pressure switches. Cost me £25 plus fitting £40 by local plumber. Could be of use?

nick, March 2009