Baxi Maxflow Combi RM

[bygravey1]

Have a Baxi Maxflow Combi WM - approx 2.5 yrs old.

Worked like a dream until recently the air flow monitor neon comes on and cuts the hot water/heating. Does so intermittantly and can take up to 15 attempts turning boiler off and turning back on before lights again, then can go for a couple of hrs before doing again. Checked flue and no restriction.

Lots of suggestions in the manual - any obvious quick wins?

Thx for your help.

 

[bygravey1]

anyone any suggestions?

Thx

 

[budstar]

Did you ever get to the bottom of this? We have EXACTLY the same problem and it's been intermittent since June. Driving us mad.

 

[ChrisR]

SOunds like a standard problem, which will unfortunately need a standard qualified gas man to fix.

 

[budstar]

SOunds like a standard problem, which will unfortunately need a standard qualified gas man to fix.

We've had our engineers in 5 times now since June and it is still not sorted. They have tried various things, including (but not limited to) replace PCB, replace AFM button, checked air flow, looked for loose connections, and they are a reputable company, but seem to be stumped.

So any clues as to what the standard problem is, would be most welcome!

 

[ChrisR]

I'd have changed the air pressure switch by now. They can be intermittent and do funny things. As can temperature sensors.
When boilers get awkward, an element of "changing things just to eliminate them" gets valid! If they can't catch the boiler reliably going wrong, have some sympathy, tho 5 times sounds a lot.
I'd have called Baxi too, there are always boiler-specific weaknesses. Nobody knows them all.

 

[sam73]

Check for condensing water inside the APS rubber tubes. This usually happen in winter time when the outside temperature drop down and condensing water built up inside the tubes.

Alternatevely it could be a Baxi serial problem with the APS

 

[apcosantana]

Didn't have the airflow monitor neon coming on but it would nearly always shutdown less than a minute after the burner had ignited.
I checked everything I could and there seemed to be no reason for its intermittent reliability other than the PCBs
I got a new Baxi Maxflow Combi WM main PCB, installed it, reset the safety thermostat and slightly adjusted the trimmers; now all seems well. It was just over £100 for the board though. The firmware is slightly different from the old board in that it starts up on CH cycle for 5 secs. then stops for 10 secs. then starts up again and continues. This seems to eliminate pipe hammer on start up. HW just starts up like the old board.