Baxi ignition

I have a Bax Barcelona 100 HE boiler. The boiler has been locking up upon startup (to red light) more and more frequently recently.

It is an intermittent problem. I would appreciate some guidance on troubleshooting whether to order electrode kit and/or ignition

I hear relay clicks followed by retries and red light. When it is working I think I hear an additional click (is that spark generator?) Usually, if the boiler fails on the first attempt, none of the attempts work. Occasionally, I have witnessed the boiler fire up on the 3rd/4th attempt.

My thoughts and plan:

- Replace the electrodes (they look a bit corroded and are pretty cheap). Is there a way to test these? No difference from a wire wool clean. The engineer tried to get a spark from electrode to insulated screwdriver he was holding - should that work anyway?

- replace air box and combustion seals as they are starting to disintegrate

- Ignition pcb - could this be at fault, even though the boiler does still work sometimes? Presumably hard to be sure it needs to be replaced in advance of trying a new one

- Spark generator - could this be at fault, even though the boiler does still work sometimes?

- The condensate drain was half full but did not seem blocked. I haven't tried removing the white lead to rule it out but I would have thought that the boiler would light, then shut down if there was a problem with that?

Thanks for any help and guidance

Andrew

Reply to
Andrew
Loading thread data ...

In message , Andrew writes

First - lets look at the relevant part of the sequence and ignoring all the peripheral rubbish so you can decide where it'#s falling over, since your description looks a bit confused

with a call for heat from the main pcb, the sequence board brings on the fan which in turn causes the air pressure switch to transfer from the normally closed to normally open position. This feeds back to the sequence board which does two things - it opens the pilot valve and initiates the spark (generated on the sequence board). The pilot light is sensed electronically on the sequence board via the FS electrode and then the main solenoid is energised to bring on the main burner

Boiler seals and such will interfere with the APS operation

The spark generator is on the sequence board

condensate trap - not sure on this boiler without looking at the manual

does the pilot light?

Does it keep on sparking after the pilot has lit ?

is the spark electrode generating a spark across the pilot jet

is the sense electrode in the pilot flame?

Answer these questions and you will be in a better position to home in on the problem

whatever,. It shouldn't be too much of a problem or too expensive to sort out

Reply to
geoff

Change both the electrodes, you can buy them as a kit Change both the G2RL-2 relays on the ignition PCB and check the the board carefully for any dry joints Check that the fire door seals are perfect if not replace them.

MILs Barcelona is now 9 years old and apart from the above is still working fine.

-
Reply to
Mark

Thanks for your reply - the pilot was not lighting. It retried (click of relays, but no spark presumably) 4 times until locking out.

I've ordered combustion and air box seals, and a new ignition kit so hope that will improve things.

thanks

Reply to
Andrew

Still a bit headless chicken approach and will in all probability achieve f*ck all

Air seals may be a problem, maybe not

Ignition kit - I presume you mean electrode assy - you're wasting your time, the sequence isn't getting that far

Are there volts (240ac) to the pilot valve some seconds after the fan comes on?

If yes, then I would say it is the pcb, if not, then, I would expect that the APS is not transferring. You should be able to hear the APS microswitch clicking in

And ... as for changing the relays on the sequence board ...

another red herring

One thing you can do to test the APS, on your own hewad be it and only of you're confident ...

suck or blow (gently) down one of the tubes to the APS so that it makes the microswitch transfer, does the boiler spring into life?

If so, then stop immediately, but you have confirmed that the fan is not causing the APS to transfer for whatever reason, and that the rest of the system is OK

do that and report back, and ignore useless advice from others

Reply to
geoff

thanks - as the parts are inexpensive compared to a call-out, I thought it worth just getting them all in one delivery. As you can tell, I'm no expert but I'm keen to understand how the boiler should work and what it might be doing wrong.

The combustion door seal was badly disintegrating when the door was removed, so that's the first thing I'll do. I understand that this could cause multiple problems like dangerous gases leaking, condensate escaping and showing a leak at the top of the cabinet (which I can see) and, the flame being shifted so it's not properly in the detector

- when it gets as far as producing a flame that is!

The electrodes looked corroded, so I thought it worth changing them too rather than just some wire wool cleaning.

Regarding the sequence, I do hear the fan come on, and then shortly after I hear the microswitch/relay sound as it tries to go through the ignition sequence. So, I assume that the APS is OK. The iginition sequence does complete sometimes.

I suppose that the end result may be that the ignition PCB needs to be replaced, but I thought it worth doing the cheaper basics first. The puzzling thing to me is why it works sometimes and not others. I suppose that dry or bad joints on a PCB could cause this. The only thing I could think of is that something is getting leaked on and drying out over time.

thanks again

Reply to
Andrew

Baxi Barcelona

A: doesn?t have a pilot light B: doesn?t have an APS

?"ignore useless advice? is the best advice you have given so far.

-
Reply to
Mark

Yes, I looked at the sequence board and went into the wrong boiler

apologies there

- however, just replacing HT leads and relays ... just in case is not the way to go about diagnosing a boiler problem

the fan operation is monitored by a hall effect sensor in the body of the fan

Reply to
geoff

See apologetic post

could be the pcb, but check out the wiring first. Where the loom connectors go into molex connectors, you can get wires which break but are still touching

Reply to
geoff

Well there you do have a point, But i am reliably informed (Pextron) and by my own experience with this boiler that almost all ignition lockouts, if indeed that is what the OP is getting, are cured by replacing the HT and flame sensor AND the two G2RL relays, cost to do this is about £14, don?t think you could even get a ?plumber? out of bed for that cost outlay.

Door seal are also worth replacing while you are at it, as a leaking seal is common and can cause safety lockout which people mistake for ignition lockout, not helped by logic board often misrepresenting LED fault code (source Pextron again)

Fan not running or below threshold would cause ignition lockout but you would not get an ignition sequence started, ie no repeated relay clicking as described by OP.

-
Reply to
Mark

Really?

Do you mean Pektron, the manufacturers ofd the sequence pcb?

Not Baxi, the boiler manufacturers

A statistical spread of one boiler?

I no longer repair the pcbs myself, (which is why I got the wrong boiler

- the pcb is used in several boilers) but I asked one of my workers that does, and that's just not true

Well, that's certainly true

Wel;l, absolutely, especially as the OP said that they are not in a good condition

Reply to
geoff

yes sorry speling eror.

FUD, little point in continuing this really.

-
Reply to
Mark

Well, since cracked joints on the molex connector are a far more common problem than relay failure (as you said - not an AC fan), then ... no

Reply to
geoff

Yes and i did also say check the board carefully for dry (or cracked if you prefer) joints in my original post. Only the molex connector? my board had more bad then good and that was in year two, by year 4 it stopped working again and thats when i discovered i had a relative working at Pektron.

Feel free to list the common _component_ failures that are found on this board.

-
Reply to
Mark

Have you informed the anthropologists?

To quote your previous post

"But i am reliably informed (Pextron) and by my own experience with this boiler that almost all ignition lockouts, if indeed that is what the OP is getting, are cured by replacing the HT and flame sensor AND the two G2RL relays"

is there something missing there?

When I say mainly on the molex connector, I mean, mainly on the molex connector. That is by far the most common cause of pcb failure

absolutely and without doubt

When it comes to relays, there is only one which is prone to failure, the one which drives the gas valve solenoid, although it's by no way the most common failure mode.

We've prolly repaired several hundred this year (The pcb is used on several boilers e.g. Keston (slightly different f/s configuration))

I had about a dozen come in today from one company, I'll ask the engineer to list the failure modes for me

Reply to
geoff

Im sure i did say in original reply to OP, but have expired that part of the thread. ?Check ignition pcb very carefully for dry joints? as that is as you say usually the start of the problems, but we got onto relays and component failure.

I cant find the schematic for the ignition pcb and it is 5 years since i last needed to look at it, but from memory the Gas valve IS switched by one of the G2RL relays but cant remember what the other one does.

Ok that would be nice to know.

-
Reply to
Mark

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.