Baxi Combi 80e Fault on Fan/Flu

[bbob]

Hi, i wonder if anyone could comment on this.

Our boiler recently developed a fault where the "fault on fan or flue" light would illuminate.

I can hear a faint clicking and the "flame" LED flicks at the same time, but the boiler doesn't light. After 3 or four attempts the fault light comes on.

This doesn't happen all the time, it seems to be related to whether the boiler has run recently.
If I leave it for half an hour or so, it will fire up.

Also, if I run the hot water with the heating on, it will usually be fine. But after I have say run a bath full, when I turn it off, the boiler will shut down, and then wont fire up again until a half hour or so later (same fault light).

we've had a local gas engineer out to look at it, we had the heating on when he came, he switched it off, back on again and it wouldn't fire up. He hasn't even looked inside, but told us it needs a new PCB.

I guess what I'm asking is, could he tell from just watching the boiler that it was a PCB fault, and not something simpler (cheaper).
Is there anything I could check before calling him back and getting the PCB fitted?

Thanks in advance for any advice...

 

[namsag]

Personally i would be checking the air pressure switch first especially at a tenner as opposed to ninety odd quid if it needs changing

 

[bbob]

is there a way to simply check this switch?

looking at manuals online, this has 3 wires? a common, NC, and NO?

If i put a test lamp/meter on these connections which should show voltage if all is well? I'm assuming the common will be live all the time and the others shoudl switch when the boiler fires up?

Can I test this without disturbing any of the gas system?

thanks for the help

 

[Slugbabydotcom]

If the 50º light comes on and the fan doesnt run; nine times out of ten its the fan relay not sending power up to the fan. A very common problem which is sorted by a new pcb. Sometimes the 30º light comes on with it

I can hear a faint clicking and the "flame" LED flicks at the same time, but the boiler doesn't light. After 3 or four attempts the fault light comes on.

You may have another fault from hereon in the sequence ie fan, APS, gas valve, flame sensing or gas pressure fault but if I was looking at it I would be ruling out the PCB first

 

[bbob]

i can hear the fan come on as soon as the heating/water is turned on, and the 30° light never illuminates, just the 50°

 

[Slugbabydotcom]

Listen carefully to find where the noise is coming from
If that clicking is the sound of the spark generator, then the APS has activated and you need to know if there's any gas coming out. You now need a corgi bloke to connect a manometer on the gas valve to check this.
Meanwhile you could check the coil resistances on the gas valve and see if theres any current geting through. Where the wires go is all there in the MI's