Video: Promax SL issue

[bolst3r]

I have an on-going issue with our boiler which is presenting as follows:

• Tries to fire, burner briefly starts
• Burner goes out after 1 second
• Cycle continues until the boiler locks out
• If you leave it a day to two and reset it, it might fire up again, it was regularly locking but would start immediately when resetting but that has stopped now

My plumber came out due to a leak from the heat exchanger manifold and managed to successfully change it and stop the leak. Whilst he was here he did the following to try and sort my issue:

• Cleaned the condensing container (was full of soot)
• Checked and cleaned the burner
• Checked the burner seat/seal to make sure it was secure
• Replaced the cover seal
• Checked the flue seal
• Checked the efficiency of the burn and carbon monoxide
• Checked the main gas feed and regulator and we're getting between 24-18.5
• Checked the ignition (although this was replaced 12 months ago)

Not sure where to go next, the plumber said he could change the gas valve, that would perhaps be the first thing he would check, but before I do this I wondered if someone could look at the videos I took and maybe shed some light on anything else that should be checked. I know the PCB can be funny on these things...

VIDEO OF IT WORK

VIDEO OF BURNER WHEN WORKING

VIDEO OF IT FAILING TO LIGHT

VIDEO OF THE LIGHTS WHEN IT FAILS

 

[CBW]

Following the fault finding in the manual, the spark gap, some wiring and the burner need to be checked. One of the more experienced Potterton pro’s might be able to help, or call Baxi for a fixed price repair.

 

[picasso]

Have the lead and the connections on top of the condensate trap checked.

 

[sugarlips]

the flow switch situated at the top right side are notorious for sticking causing this very fault. link it out and then try it.

 

[bolst3r]

hmmm, It sounds like it could be a rectification issue, going by this video from Baxi.

The cable has been disconnected as per the video instructions and it still exhibits the issue...

Is there anything else I can check to get to the route cause?

 

[bolst3r]

the flow switch situated at the top right side are notorious for sticking causing this very fault. link it out and then try it.

ooof, that looks a pig to change according to the Baxi help videos this usually presents with a certain light error and mine doesn't show that. Leads me to think it's something else...?

 

[bolst3r]

Have the lead and the connections on top of the condensate trap checked.

I believe by disconnecting the white lead from the ignition to the condense trap, this would rule that out as the fault? (as per the Baxi video below). I could be wrong, happy to clean and check something else...

 

[bolst3r]

Following the fault finding in the manual, the spark gap, some wiring and the burner need to be checked. One of the more experienced Potterton pro’s might be able to help, or call Baxi for a fixed price repair.

i'm tempted to check and clean all the connections in the PCB. There was moisture in the case due to a leak... clutching at straws I know

 

[ianmcd]

i'm tempted to check and clean all the connections in the PCB. There was moisture in the case due to a leak... clutching at straws I know

Get a hair dryer on the PCB to dry it out and heat it up and see if the same fault persists

 

[picasso]

If that does not work check the ignition and rectification probes are clean.

 

[bolst3r]

Get a hair dryer on the PCB to dry it out and heat it up and see if the same fault persists

the plumber did do that for a little while and it didn't seem to make a difference. In my mind I felt water could lead to a short circuit but wouldn't that be binary? It comes on from time-to-time

 

[bolst3r]

If that does not work check the ignition and rectification probes are clean.

It had a new ignition/probe about 12 months ago. That being said, sub standard parts can break down pretty quickly. Assume it's ok to remove and wet 'n' dry with a fine grade to make sure there is no carbon build up on the end?

The old ignition that was replaced was like some old shrivelled twig. I'm suprised it even worked. It clicked 3-6 times before firing with a loud whoomp. Much better when it was done

 

[bolst3r]

So over the weekend I removed the ignition, cleaned the prongs and adjusted the gap as per specifications as it was too wide. I also removed the PCB, inspected the connections and reassembled. It's been working off/on since (didn't work after the ignition work, so I don't believe it's that).

I wasn't able to totally split the PCB and look at the back of the circuit board as the bottom part of the case didn't feel like it wanted to split, and I didn't want to force it. Is there a technique for opening it fully?

One thing I did noticed when it wasn't firing was a very faint sound of arcing from the PCB area. There are two defined relay clicks in the firing sequence, then I can sometimes here this really faint noise. I've tried to wiggle wires in the vein attempt of tracking it down but was unsuccessful.

I wondered if anyone has experienced a similar issue?

When the PCB goes, does it exhibit with the same symptoms?