Baxi 105e Flue problem Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[ericmark]

My daughter had a problem with her Baxi combi boiler which seemed to be connected with the flue. Originally it seemed to be linked with a broken clamp around the flue and as a result the pressure differential switch was not activating. Repairing this helped but then it went off again at this point we found some insulation had dislodged and fell on the burners but not until we had tried to adjust the switch. I noted before we adjusted switch it seemed to have a centre position where a small pressure differential caused it to change but larger one caused it to return and after fiddling this no longer seems to be the case. So was the switch faulty to start with or faulty after we tried to adjust. Also three cables on the switch blue N/C then brown and black when my son-in-law removed and replaced the brown was on common and black on N/O but the instructions on lid say brown on N/O and black or common tried both no luck. The Brown is live and unless connected to black on start the fan does not run. Boiler type 105e I think we will need to get a baxi engineer to replace the boiler lining but if I could get it to run to give hot water while waiting it would be bonus can anyone help?
Eric

[htg engineer]

If looking at the air pressure switch connections from the front, the wires go Black, Brown, Blue. Sensing tubes - white to right.

The pressure tolerances on the air pressure switch are very very fine. (0.2 mbar I think) adjusting this could cause problems- You can buy a new air pressure switch for about £15.

Is it a vertical or horizontal flue ? if it's vertical - look at the flame picture (should be small blue cones on burner) if the flames are lifting off the burner then there's a break in the flue somewhere.

Hope this helps


htg

[ericmark]

Thank you very much. Found original fitter not Corgi so playing safe kids at my house having bath at moment and gas fitter due tomorrow so not taking a chance.
If it had been a week to wait I would have tried to get it working but for a day not worth it.
Eric

[ericmark]

Just as well I didn't try to fix it seems main board needed replacing it was not working ignition coil. They also replaced the switch I had played with and the ignition coil it's self. Hind site I think there were a number of faults and I had found one and stopped looking.
A little worried when the gas fitted did not put any new heat sink compound on heat sink when moving it from chip on one board to chip on new one. Could not get good look but looked like a 78 series voltage reg.
Also dip switches on new board where not on old board so I would have not been able to set up.
All running now but I think I'll hang on to old faithful boiler I have these new fangled boilers have too much to go wrong.
Thanks for your help.
Not too expensive either £175 fixed fee from British gas at those charges not worth messing with how do you gas fitters make money?
Eric

[htg engineer]

Not a bad price at all, considering the PCB is about £130 and the air pressure switch about £35 to buy over the counter, you can get them cheaper if shop around online, like the PCB for £90.

Obviously BG will get them cheaper as they'll get discount.

But as I have said on here a few times, Baxi are cheap for spare parts compared to other manufacturers and all parts are easily accessible and easy to replace. I bet it took the engineer 15 mins to change both parts.

I like Baxi boilers, I'd install one in my house.


htg

[ericmark]

Don't think BG guy liked them three trips. First he found fault and ordered parts. Second different guy said it was wrong part and ordered more bits. Then first guy returned found he was right in first place but new board had dip switches not on old board and they were set wrong so about 6 hours on site in total.
I don't think BG made any money.
Baxi wanted £299 but that included 12 months guarantee on whole boiler.
Eric

[htg engineer]

I could have replaced the PCB and Air Pressure Switch, in 20 minutes for about £100.

Not sure why they have to order parts, when most places stock them. They are easily purchased over the counter, at HRPC and places like that.

£299 too steep, not sure why they'd offer 2 moths warranty on whole boiler - they wont if it turns out the parts have failed becasude of incorrect installation eg if diverter or pump needs repairing and there's no ihibitor in system.


htg

[freddy871]

Probably not relevant now .. but had similar problems today with Baxi 105e showing fan/flu error. After replacing replacing APS with no sucess turned out to be a small cobweb found in Venturi... Removed cobweb and hey presto all working again.