Faulty Baxi 105e / Flashing "fan / flue" (50 degre

[stevelanc]

Hello all

I have inherited a "non-working" Baxi 105e in my house that I moved into a couple of weeks ago.

From reading posts about these boilers if I describe the symptoms it probably points to a faulty PCB - but if anybody has any other ideas I'd be grateful (Kevplumb - you are probably the man!!)

I have no heating at the moment and would like to get it fixed before the snow sets in.

The symptoms of the boiler are - up until about a week ago it worked on and off for varying lengths of time but progressingly shorter. When firing the boiler up - the heating/water LEDs lit up together with the orange burner LED. Then (after a while, could be 5 minutes, could be 2 hours) it would trip out and the LED above 50 degrees (the fan/flue LED starts flashing). I have checked the fan and it spins freely and when putting an electrical tester to the live terminal power gets to the fan for a split second and I hear a click (sounds like a relay).

The flue pipe is completely clear.

For the last week the boiler does not kick in at all - only the 50 degree LED starts flashing after about 30 seconds. I can still hear a click after resetting or selecting hot water or heating.

Assuming it is the PCB does anybody know where I can get a replacement (secondhand is OK) or my faulty one repaired.

Any comments / advice will be greatly appreciated.

Thanks
Steve

 

[newcomers]

Could be the air pressure switch. I replaced 2 of these on this boiler last week

 

[baxpoti]

Clean the venturi

 

[Agile]

I am not under any time pressure to get a repair done quickly so I would measure the APS to see if it operated when the fan started.

Perhaps I might disconnect the wires and electrically test it.

Normally I would then remove and clean the venturi. I never blow through them as that does nothing.

In this particular case the OP has implied the fan is only powered for a "split second".

Most boiler circuits would allow at least 5-10 seconds for the APS to operate. So I would check that the APS is correctly wired from the interconnection plan.

If everything checks out then I would suspect the PCb as the last and most expensive item.

Tony

 

[Slugbabydotcom]

For the last week the boiler does not kick in at all - only the 50 degree LED starts flashing after about 30 seconds. I can still hear a click after resetting or selecting hot water or heating.

If it isn't the PCB I will eat my hat. Theres a lot of 80e's and 105e's around here. I have changed so many that I now keep 2 as spares. One day they may become as famous as suprima pcb's for going wrong.
Part number is now 5112380 [changed from 248074] About £80 if you know where to look. If you dont know where to look search for a site the likes to 'keeptheheaton'

 

[Agile]

I have not seen that fault display when it was anything other than the fan/APS yet.

The most common fault I have encountered with the PCB is that it gets up to temp on CH but then fails to ever come back on again.

Have you seen that ?

I have also been called where someone else has changed the PCB but it has not cured the problem and its really the min gas pressure setting or the flame detection electrode which seems rather critical.

Tony

 

[ChrisR]

With the Slug on this one. Signature split second fan-on pulse points to pcb.
The "Instant"'s do it too - 248731.

 

[Slugbabydotcom]

The most common fault I have encountered with the PCB is that it gets up to temp on CH but then fails to ever come back on again.

Have you seen that ?

I should keep a diary of symptoms and causes. I recall one like that where the owner had to run outside to reset it but it was about 4 months ago.

I have not seen that fault display when it was anything other than the fan/APS yet.

That may be the case on other boilers but not these in my experience. I always check the fan anyway just to cover my arse.

 

[stevelanc]

Thanks to everyone for their advice.

It was the PCB.

I got one from a website that "keeps the heat on" - ordered it Sunday, it arrived Tuesday, and took me half an hour to fix.

Steve