baxi 105e fault. tried everything and still wont fire up !!

[jeffc1970]

been directed to see if anyone has come across this fault before.

I have a baxi 105e, on both water and heating it goes through all the motions as it should ie fan kicks in, ignites then lights the burner up briefly but then goes out within 1 second, repeats this and no warning lights come on, Ive been on with this for a week and so far replaced..

Pcb
gas valve
temp sensor
flame sensor

checked the gas supply into the house at 41mb and 37 hen the burner demands gas.

checked the 2 black wires voltage at the gas valve 19v (its on lpg)
Ive switched over the jumper for the lpg.
tried it with flame sensing wire
stripped everything out cleaned and re assembled.

and to rule out my bad luck of having 2 faulty pcbs tried my pcb on another boiler and that works fine , all 3 pcbs wont fire up mine.

Ive spoke to the baxi tech guys and the senior tech guy and they cant help me


realy appreciate any input before I go out and fit another boiler

 

[Kev F]

had the same problem mate changed both the pcb and gas vavle very expensive after the helpline said it could be NOTHING else, and still didnt work apologised to customer and told her to get baxi out, who changed both the pcb and gas valve and the pump, left the job and got one of their other technicians out not sure what it was in the end so would be interested to see what it is

 

[fitz1]

check your earth and neutral connections

 

[shambolic]

check your earth and neutral connections

What he said if you have reverse polarity most modern boilers wont light as the flame is rectified through the neutral and earth connections.
In reverse polarity you will get a reading of 240v neutral to earth(this should be 0-15v)
If this is whats happening then you need a spark to check the wiring in the house but it is normally the spur at fault (broken neutral).
This will make the boiler light for up to 10 sec while it is trying to sense a flame. It thinks there is no flame and shuts down on the FSD.

 

[jeffc1970]

check your earth and neutral connections

What he said if you have reverse polarity most modern boilers wont light as the flame is rectified through the neutral and earth connections.
In reverse polarity you will get a reading of 240v neutral to earth(this should be 0-15v)
If this is whats happening then you need a spark to check the wiring in the house but it is normally the spur at fault (broken neutral).
This will make the boiler light for up to 10 sec while it is trying to sense a flame. It thinks there is no flame and shuts down on the FSD.

checked polarity with mulimeter and this is fine, just been back onto baxi and they say as a last resort try spark generator , will give it a try but not hopefull

 

[Kev F]

forgot to say i checked the polarity and it was fine then changed the spark generator and still nothing, in a horible way im glad im not the only one who has had problems with this boiler

 

[shambolic]

Is the flame passing all the way accross burner to the rectification probe I have had this on LPG mini's where the flue length is too short and they have forgot to put in the ring to reduce pressure in the inner flue resulting in flame lifting and not crosslighting.
I cant see it being spark generator as it is lighting!!!!!!

 

[namsag]

Had one doing similar although not as quick it was about ten seconds and it turned out to be a faulty multipin plug on the gas valve it needed wedged slightly to keep it in position.
Did you change both temp sensors

 

[jeffc1970]

it goes through the motions and a low flame passes across the burner as soon as it reaches the right hand side it goes off and a click in the valve is heard at the same time, it then does the same again..

I only changed the flame sensing probe and left the other as it looks to me like the other one is just to light it and it does that and it is detecting that there is a flame as it stops igniting ? iyswim

Im struggling to get my head around Im going to have to replace this boiler to get it to work

 

[baxpoti]

checked the gas supply into the house at 41mb and 37 hen the burner demands gas.

The gas valve needs to be set up for LPG.

 

[jeffc1970]

checked the gas supply into the house at 41mb and 37 hen the burner demands gas.

The gas valve needs to be set up for LPG.

can you elaborate on that please ? tried adjusting the larger nut (hi flame? ) and no different ? fault is exactly the same with both valves fitted.

 

[HarrogateGas]

Are you compentent to be messing with Gas valves-particually on LPG???


If only you would have got a competent Corgi in the first place it would have cost you a lost less in the long run.


Lesson learnt?

 

[jeffc1970]

Are you compentent to be messing with Gas valves-particually on LPG???


If only you would have got a competent Corgi in the first place it would have cost you a lost less in the long run.


Lesson learnt?

you would think so wouldnt you Ive had 3 different corgi engineers out allready this week and still no further forward!

 

[dave18]

Simple.................

Change the lead to the spark electrode

and the lead to the flame sensing electrode.

use only Baxi genuine parts about GBP3 for each lead........

cheaper than a new boiler.


David.

 

[jeffc1970]

Simple.................

Change the lead to the spark electrode

and the lead to the flame sensing electrode.

use only Baxi genuine parts about GBP3 for each lead........

cheaper than a new boiler.


David.

Ive allready checked the lead for continuity and its fine