Baxi 80 combi eco not firing up

[zubsgela]

Hi i have a baxi combi 80 eco i have replaced the diaphram on the boiler after it had ripped and now found a secondary fault on boiler. The hot water works perfectly however when i turn the heating on the boiler locks out. If i keep the micro swith on the hot water side of the manifold pressed the boiler lights up and provides heating. Can someone help me out with this..

 

[Andygasman2010]

When you say it locks out, do you mean the red flame-failiure light comes on?

 

[zubsgela]

Yep the flame failure light comes on.

 

[Andygasman2010]

Does the burner attempt to fire when you put on a heating demand? How far does it get in the sequence? I.E. Demand - pump - pump proving switch - fan - burner.

At what point does it lockout?

 

[zubsgela]

pump, fan, burner ignigtor all work. flame even comes on for like a couple of seconds then shuts of, boiler retires to light for a second time then it cuts of. But if i push the micro switch that is pushed by the hot water pin on the manifold then the boiler lights porviding me heating. so far i have changed the diaphram and the overheat stat.

 

[Andygasman2010]

Sounds like it's not rectifying. When the burner ignites does the sparking continue on until it extinguishes?

 

[zubsgela]

Yep the sparking stays continous but shuts of after the flame extinguishes. When swithced to hot water the boiler seems to be running fine. fault only occurs on heating side. Cud it be the divertor valve???

 

[Andygasman2010]

The problem is that the PCB isn't seeing the burner light during initial heating demand so it tries a few more times before locking out. It's ok on hot water because gas pressures are higher. I'm affraid you'll need to get an RGI in to do any further checks as they're either gas pressure related or within the combustion chamber. Shouldn't be too difficult to sort out though.

Hope that helps.