baxi 80 eco not firing (when hot)

[mike291201]

Hi all,

Realy hope you can help me with this as its been getting on my nerves for a while now.

I have a baxi 80 eco combi boiler, it all works fine when the heating system is cold. As in, if i switch the central heating on it fires up no problem and the same with the hot water, fires up fine.

The problem that i have is when the central heating is on and it gets up to temp, the flame goes out. (which is correct i know) but after this it wont relight again. The pump and fan keep running but theres no flame ignition. If i turn the hot water tap on, it wont light either.

I have to wait for the whole system to go cold, and then it will be fine untill it gets hot again.

I've tried resetting it on the switch on the front and also the little switch on the safety thermostat but it doesn't help.

Its had a new temp sensor and also a flame sensor but with changing these it hasn't helped atal.

Any ideas much appreciated

Mike

 

[MANDATE]

that type of heat related problem would lead me to examine the printed circuit board for poor soldered joints.

 

[mike291201]

cheers ill take a look if theres any obvious signs.

Also, is there a way of checking the spark generator is working correctly??

 

[MANDATE]

Don't think I can help on the spark generator.
I know sometimes the spark may not go across the gap as it should.
I would clean the electrodes and check the size of gap is to specification.
Make sure the position is correct.
You may find after use, signs of arcing in the wrong place.
I take it you can't see it in operation.

You could always try a small piece of paper between electrodes. If it's not working it will not burn it.

 

[mike291201]

ok, very strange now. I think it could bad connection somewhere.

Ive taken the front off the boiler and have had a look at the pcb. Theres not signs off burnt joints so it seems ok.

The thing is, with the boiler hot i tried to run hot water and it didnt light, but with the water still running i started to lift the pcb unit back up into position and boom, it lit. So i tried again, put pcb down (the pcb sits on a hinged front) tried to start heating, nothing until i started to lift the pcb again.

There isnt like a saftey tilt switch in there somewhere or is this realy the case of a bad connection somewhere??

 

[Agile]

I know sometimes the spark may not go across the gap as it should.
I would clean the electrodes and check the size of gap is to specification.
Make sure the position is correct.

You could always try a small piece of paper between electrodes. If it's not working it will not burn it.

Do you really think that you should be advising a DIYer to open the CC and do those things?

He should call an RGI for those that.

Obviously now there is a fault on the PCB. I have always found that model to be electronic faults but in this case there is apparently a bad connection.

These are usually bad soldered joints and particularly on plug connections which are mechanically stressed when the plug is inserted or removed.

Tony

 

[mike291201]

i do understand your concern but im not doing anything silly like disconnecting pipes or anything.

Im and electrician by trade so i know how to do thing safely on that side of it.

Just looking for pointers that all before i call someone out and the just go straight to it.

Cheers mike

I take take it you think its just a bad connection somewhere??