Baxi 105e No CH or HW Flame Failure and Fault on Flue or Fan

Mattsell · 20 Jan 2011

Hi all, Please can you help me. I have a Baxi 105e boiler 4.5 years old. Its just stopped working. When it is turned on the Flame Failure and Fault on Flue or Fan lights up. No sounds come out of the boiler. The fan motor is slightly corroded.

Do you think its the Fan?

The hot water microswitch is fine as for anything else I'm not sure. It says in the fault finding (if I got it right), check flow microswitch , something about Check primary temperature sensor. Cold resistance 11K ohms, how do I check this? Then Check fan is not jammed (its not), finally PCB.

Any suggestions? Many thanks in advanced.

muggles · 20 Jan 2011

Could be the fan, especially if that isn't running, would be worth finding out if there's power going to it, probably best to get an RGI in though

bengasman · 20 Jan 2011

This is not the kind of fault that is suitable for diy, best to get a breakdown specialist out for it.

Ray84 · 21 Jan 2011

quite right its not a repair you can carry out yourself. although it points to a fan/flue point id guess its the PCB though in theory could be a sticking APS or fan i think probably the pcb.

Ray[/i]

Mattsell · 21 Jan 2011

Thank you for the advice. It was strange that I tried it from cold and I held in the Hot Water microswitch and it fired up, I then let it go and it stopped again.

No it stays quiet no noise from fan pump etc.

Mattsell · 22 Jan 2011

We have had an engineer out it. Unbeleiveable my little boy must have been playing with the thermostat that's why no demand! Typically silly mistake!

However, It all worked for a bit and then same fault lights. This time pump is on, still no fan.

Engineer didn't know what is wrong so he phoned Baxi and they think the problem is Air Presssure Switch. Which goes against what's in the Fault Finding solutions I found in section D on
http://www.partsarena.com/baxi/System/DATA/Dx/DS1/installation/2288/I05-2288/I05-2288.htm

Which asks to check Primary Presure sensor and possible PCB fault.

Air Pressure Switch coming Monday... so hopefully its right. Sound Right to anybody?

Thanks

fine tune · 22 Jan 2011

air pressure switch should do it , boiler does a quick check of parts when first switched on and if the aps was faulty would not go any further , fans usually ok on these ,

GodKnows · 22 Jan 2011

Hi all,

Get an experienced RGI out

Second guessing and parts swopping isn't popular in our field. A waste of your money and our time

A decent guy would take about 2 mins to suss out the problems with your boiler....

Mattsell · 24 Jan 2011

Plot thickens. Engineer came back, replaced air pressure switch and same fault. Said it was PCB and would be £230 +VAT to replace. So I said we would have to think about it.

Decided to look at the PCB myself, looked at connector A5 7 & 8 and wires were loose, so fiddled with them and original fault went away, now I have a new fault with the Fault on Pump or Low Pressure (triangle in a circle, red light flashing). Pressure in system, Next it says check the tap on the automatic air vent is open, so I opened the screw (took it out!), still fault.

Last check is Primary Flow Valve Diaphragm damaged? To options replace it or flow rod obstructed. (Can't find this in the manual)

Can anyone point me in the direction of the Primary Flow Valve please?

Many Thanks

Ray84 · 24 Jan 2011

sounded like the pcb!

flow switch is the one located on the top side of the diverter valve (the hot water microswitch is at the front of it.

When the pump runs the pin should pop up and hit the microswitch so if its not doing that might need a clean/diaphragm/pump (probably just the first one seeing as the systems not been on much might be sticking)

Ray

Mattsell · 24 Jan 2011

No worries Ray, thanks for the reply. I thought so too before engineer came out!

Both pins on DHW and CH pop out and make with microswitches (green lights on the front)/, Fault still there, quite strange, as I thought this would be the problem.

Ray84 · 24 Jan 2011

try holding the reset knob in its position for 10/20 secs. If the pump runs and microswitch makes but still comes up with a pump error it could be the microswitch itself is faulty else could still be the pcb
could you check the microswitch was making and breaking contacts ok?

Ray

Mattsell · 25 Jan 2011

I think the 2 microswitches (if DHW and CH on at same time) are making, and have conectivity (buzzed out) ok. I will check again tonight, when I'm back from work.

Mattsell · 25 Jan 2011

Had another look at PCB, as microswitches were making, took board out to check under the baord. Found that The wires in the connector weren't making with the connector on the board! Had multimeter over it to check continuity and boiler started to fire than original faul. Sorted connections now so back to same fault as top of post.

Am thinking it is PCB, or maybe just a relay on the PCB, there is no 240v on Fan connections from PCB, so thinking of hot writing this from supply to test if this is problem. Will this work?

Mattsell · 25 Jan 2011

Tried hot wire, fan powers up fine, put I think because it doesn't do the checks in the correct order or fault still on PCB boiler doesn't fire up.

The actuating rod to CH microswitch goes in and out all the time. I tried giving 240v to the fan after turn on but this didn't work fault kicks in too quick.

Not sure what to do?! Buy a non-refundable PCB as this is what Baxi manual, fitter, and Ray think it might me. Or pay out for someonelse to come out, who may say PCB!?

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Baxi 105e No CH or HW Flame Failure and Fault on Flue or Fan

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