Baxi 105e instant problems

[MK Heating]

Went out to look at a 105e instant earlier, Im normaly ok on these, I rather like them.

However, this one whe I arrived had the fan light flashing, reset it and it fired up, fan was pulsating very erratically, and the flame was going up and down. I checked the voltage at the fan ad was getting between 25v and 730v???

while lit the burner sounded like it was spluttering.

After a while the fan did start to spin at a constant speed, but the burner didn't improve

When running DHW turning the hot water dial down didn't alter flame size or hot water temperature

I thought PCB. But the more I think about it, the more I change my mind

 

[Billy Bob Bob]

possibly fan relay in the pcb,however if its a HE version take a good look at the aps

 

[mountainman]

possibly fan relay in the pcb,however if its a HE version take a good look at the aps

And the flue, had a boiler recently displaying similar symptoms and the flue had perforated.

 

[MK Heating]

Not a HE but Il check the aps anyway. Il get the analyser on the flue first thing. Cheers

 

[MK Heating]

Opened it up to look at the board and you could fry an egg on the big square relay, that normal? Don't ever recall noticing it before

 

[mountainman]

Doesn't sound right to me.

 

[bewsh]

I've had a similar problem on an Ariston Microgenus (horrible) - there's a plate which is riveted to the back of the burner box just above the heat exchanger, the rivets had snapped and he plate was blocking half the heat exchanger. The burner was all over the place!