Ideal Mexico HE18 intermittent re-ignition fault, update

[fourtytwo]

I wrote about this the other day thinking it was wind but it is not. Instead it seems after the heating has been running an hour or so and the radiators are all hot and the TRV's progressively closing, the boiler is modulated right down, the room stat does not shut it off but perhaps it does itself due to flow temperature, for whatever reason it ends up with FE error (ignition failure) possible when it tries to re-light. Manual intervention by pressing the reset button immediately succeeds (on 1st attempt).

Now perhaps the mods or whatever can tell me if I am wasting my time putting this on this site as i have read comments like "we do not advise on gas boilers", if that's the case please tell me rather than me hoping for an answer.

 

[blup]

I doubt it

Blup

 

[old duffer]

years ago I had a recurring issue with a combi when it would work fine then would have period where the ignition failure would occur. Tested everything and even changed the fan and the pcb (default when the NVQ "engineers" have no idea)
Then I began monitoring the conditions under which the boiler would fail and it was always when windy. The combi had a vertical flue through a roof and when I checked, the flue was being blown to the side and in doing so, was lifting the flue from the boiler...by a tiny amount....
Added metal flue bracing and replaced the boiler/flue seal and screws and it worked fine.
This was after 4 NVQ "engineers" had looked at it....

 

[Madrab]

You won't get a locked thread until you are asking specific question about doing DIY gas work, that's what's not allowed.

As far as your ignition issue is concerned then, if it can be re-created consistently then that's half the battle, as if it can be seen then chances are it can be fixed. If it is an ignition issue though then it needs opened up and that's when you're into GSR engineer territory and you won't get advice on how to do that I'm afraid.

 

[fourtytwo]

years ago I had a recurring issue with a combi when it would work fine then would have period where the ignition failure would occur. Tested everything and even changed the fan and the pcb (default when the NVQ "engineers" have no idea)
Then I began monitoring the conditions under which the boiler would fail and it was always when windy. The combi had a vertical flue through a roof and when I checked, the flue was being blown to the side and in doing so, was lifting the flue from the boiler...by a tiny amount....
Added metal flue bracing and replaced the boiler/flue seal and screws and it worked fine.
This was after 4 NVQ "engineers" had looked at it....

Yes I thought it was the wind as we have had a lot recently, there were cobwebs down the flue so I cleaned it with a radiator brush but to no avail. Guess I will just have to try and get down to exactly when it happens and make it repeatable so a GS engineer can fix it. It does seem to be after it has been on long enough for the radiator demand to reduce and the boiler throttle right back so guess I will have to get up with the lark and sit in the garage babysitting it early in the morning Brrrrrr
I don't think this flue is moving as it's tight through a double brick wall and it only sticks out of the building a few inches, but it's something to ask the GS engineer thank you

 

[fourtytwo]

Update from testing today. I removed TRV's from lounge as thermostat is also in there and I was concerned about reduced flow upsetting the boiler. I ran the heating just to the two radiators in the lounge, all other TRV's off. It ran faultlessly with the boiler cycling on and off to maintain the flow measured at a radiator between 48-61C. After 70 minutes I noticed the flow had dropped to 43C, no smoke from boiler! Found room thermostat had opened but also boiler was purging (fan running slowly and led flashing slowly so it was in a retry cycle. Sure enough the fan started to wind up and the gas solenoid clunked but no boomph of igniting gas so fan wound back down and went through a purge before flashing LF (ignition fault). So I must have caught it on try 3 of 3.

Reset it, wound up room thermostat and the boiler re-ignited no problem. Let it run a few minutes then turned down room thermostat again to open it. Boiler stopped normally and ran through it's purge cycle.

So will try this again tomorrow to see if I can get a repeat performance, might try the room stat lower to see if that opening has anything to do with the dreaded LF. Certainly a weird one. Earlier in the day I used the frost stat to force the boiler on and off many times on just the hot water circuit and the boiler started many times without a problem.

I am slightly bemused as to why it was trying to start with an open room stat, it has permanent and switched lives, Y-plan.
Maybe the purge cycle gets it's knickers in a twist sometimes.

 

[fourtytwo]

Just another update, I have been watching it and cataloguing circumstances and am pretty sure it fails after about 70 minutes because two things happen.
One is the flow to the radiators reduces as many rooms have come up to temperature so the boiler reduces output, eventually this is not enough to stop the flow getting to hot so it shuts down altogether, requiring ignition when the flow temperature reduces again.
Two is the lounge where the system CH thermostat is located getting warm and said thermostat cutting off the boiler, requiring re-ignition when the room cools a little (the hysteresis only seems to be <1degC).
Prior to these two events the boiler is lit continuously so doesn't require re-ignition.
This boiler has a fairly large combustion/heat-exchanger box in the bottom with the ignition module/transformer located directly above it, so that is certainly subjected to a fair amount of heat cycling especially as the boiler is out in the garage. It is well known in the electronics industry that thermal cycling = poor reliability so it would not surprise me if this part might have something to do with the problem (sorry mods if I have said to much there, delete as required).

 

[old duffer]

Just another update, I have been watching it and cataloguing circumstances and am pretty sure it fails after about 70 minutes because two things happen.
One is the flow to the radiators reduces as many rooms have come up to temperature so the boiler reduces output, eventually this is not enough to stop the flow getting to hot so it shuts down altogether, requiring ignition when the flow temperature reduces again.
Two is the lounge where the system CH thermostat is located getting warm and said thermostat cutting off the boiler, requiring re-ignition when the room cools a little (the hysteresis only seems to be <1degC).
Prior to these two events the boiler is lit continuously so doesn't require re-ignition.
This boiler has a fairly large combustion/heat-exchanger box in the bottom with the ignition module/transformer located directly above it, so that is certainly subjected to a fair amount of heat cycling especially as the boiler is out in the garage. It is well known in the electronics industry that thermal cycling = poor reliability so it would not surprise me if this part might have something to do with the problem (sorry mods if I have said to much there, delete as required).

so a replacement of the module will solve all issues!

 

[fourtytwo]

so a replacement of the module will solve all issues!

I hope so, still in the post..........
But there was more besides, the design and construction in the area was very poor. Rivet nut's used back to front so the practically fell out, unplated brass tags for earths so they were heavily oxidized together with poor spade terminal tension. It would never have made it out the door of factories I worked in lols
UPDATE 22/11 Having finally got the unit from the clutches of the post office it's FAULTY!! nearly dead short on LN that fried the controller (fortunately just overheated resistor and burnt plastic case). I made a mistake, I trusted a supplier on Fleabay selling used TESTED spares, never again!! Cheapest source for new including delivery found Sfix.

 

[old duffer]

I hope so, still in the post..........
But there was more besides, the design and construction in the area was very poor. Rivet nut's used back to front so the practically fell out, unplated brass tags for earths so they were heavily oxidized together with poor spade terminal tension. It would never have made it out the door of factories I worked in lols
UPDATE 22/11 Having finally got the unit from the clutches of the post office it's FAULTY!! nearly dead short on LN that fried the controller (fortunately just overheated resistor and burnt plastic case). I made a mistake, I trusted a supplier on Fleabay selling used TESTED spares, never again!! Cheapest source for new including delivery found Sfix.

so you are blaming a faulty part as being the reason it failed AGAIN on your system! Have you considered it might not have been the reason? Well at least when the brand new one arrives you can be sure that it will work this time

 

[fourtytwo]

so you are blaming a faulty part as being the reason it failed AGAIN on your system! Have you considered it might not have been the reason? Well at least when the brand new one arrives you can be sure that it will work this time

Not quite sure what you mean there, the Fleabay replacement that turned up was faulty, I was not blaming it for the original fault as it was not there.........
Anyway the new part from Sfix arrived yesterday and was fitted, not only did it work yesterday but the boiler worked this morning without fail ie past the 70minute point and re-ignited many times when hot, something it would not do before. So on the basis of one day's trial so far the problem is fixed. I will update again in a few days if it remains so Xfingers

EDIT 25/11 Another faultless run this morning and last night so I think it is safe to say it was the ignition transformer that was intermittent and failed when hot, replacing it has fixed the fault and the boiler is restored to being reliable