Baxi Combi Boiler 80e Printer Circuit Board PCB has blown?!

Hi, Hope someone can help, I found this site on the web.

We have got a Baxi Combi 80e, it was in our flat when we bought it and I am pretty sure it is around 7 years old.

Last night we noticed a burning smell coming from the boiler (it smelt like TCP!). I did not want to touch it and planned on ringing our engineer man we have used in the past the next morning, however within the hour, all the lights had gone out on the front so I turned it off in the hope it would prevent any further problems.

Boiler man came today and showed me the PCB and it (or components on it) have blown. The back is black and you can see where something has burnt and it smells strongly of being burnt!

He was concerned that the "auto-shut off fuse thing" did not go as this should go first to save damage to the PCB.

We are not sure what to do as he is not 100% sure himself. He says he can fit a new PCB for about £200 but as we do not know what caused this problem it may happen again in the near future.

Does anyone know about this or had experience in dealing with problems with this PCB?

Any advice welcomed.

Many thanks for reading.

there's no known faults with this board that i'm aware of. get your RGI to check resistances of componants on the boiler such as the fan/pump/gas valve etc, check incoming voltage is correct and change the board. it's likely to be the board i'd say but it's difficult.

Hi Andygasman,

Many thanks for your reply to this and I will pass your comments on to the gas engineer when I speak to him next.

You say it's likely to be the board but difficult, do you mean it's difficult to say it is definately the board or difficult to say that it could be the components?

Thanks for replying so dam fast as well!

it's difficult to be sure what it is. i can't see any of the components on the boiler being faulty, there is a built-in fuse on the board protecting them. Supose it's worth checking though. To be honest it's most likely just the PCB. i think they're about £140 plus fitting

What he means is although the Pcb is obviously burnt and therfore U/S its possible that the fault lies elsewhere in the boiler. I have seen a few with burnt out fan relays due to low resistance in the fan windings causing to high a currant to flow,as suggested have your rgi check the resistances before replacing the board as it may well fail again hope this helps.

Many thanks to you both, I will report back and update this topic and of course if anyone can add to this etc... I would be most grateful.

mr-crs said:

What he means is although the Pcb is obviously burnt and therfore U/S its possible that the fault lies elsewhere in the boiler. I have seen a few with burnt out fan relays due to low resistance in the fan windings causing to high a currant to flow,as suggested have your rgi check the resistances before replacing the board as it may well fail again hope this helps.

Click to expand...

When you say you have seen a few do you mean a few Baxi PCB's or a few PCB's?
I only ask as Baxi's are normally more than reliable for blowing the 1 of the 2 PCB fuses before the board itself with any fault on either the pump or fan, however i cannot think of anything else that would blow the board except what you stated?

Hi,

Just to update this now.

Boiler man came and installed a new PCB yesterday. He checked again the fan, pump, wiring, gas valve etc... All looked fine.

Installed the new board and powered on and all is working fine!

We monitored it for a good 15 mins while it fully powered up, checked heating came on, hot water etc etc...

All is good.

He reckons that if it was to blow/burnt out again it would have done it pretty much straight away. Therefore we are hoping that this will be ok for a good while now.

I found no more information about this on the web and having really examined our boiler and finding no other issues we are putting the fault down to a old PCB with old components, one of which just basically developed a fault and burnt out.

Anyway, thanks again to those that replied, much appreciated.

You seem to have been lucky!

Unfortunately many gas engineers are not very good at testing the boiler components. Sometimes they only fail at mains voltage and seem to test OK at low voltage.

Perhaps you would have accepted paying for two PCBs if the new one had failed but i would never charge a customer if I even did that.

So I always test VERY carefully and then when I repower its done with a very low value quick blow fuse in the supply.

Tony