Exotic pilot light problem

[Agile]

Holty are you suggesting that I am not able to identify faults on simple boilers?

As you know none of us have visited this boiler or had the opportunity to ask relevant technical questions.

You may not think o/h stats were fitted to this model but Kirkgas certainly thinks they were:-

an open vent system CAN have an overheat stat, fitted plenty to BAXI BBU's, they come as an accessory and are required if the vent doesnt rise up from the boiler

All I have done is to suggest that if an o/h stat were fitted, then it could be the cause of the problem and offer the OP a simple way to test if thats the case.

Tony

 

[holty]

calm down agile. i know your fault finding skills.alls i was saying is what your implying to the OP. he get someone in who at least knows the difference between a thermocouple and a precision pilot.chill

 

[holty]

plus the baxi bbus kirkgas was on about, proberbly used the same spec newer electronic bbu. that could use overheat stats.

 

[gremlin16]

plus the baxi bbus kirkgas was on about,

Thought op had a GW 45

 

[palmyra]

Sorry guys for getting back to this with some delay, my Saturday was chaos.

Indeed, it's Glow Worm 45, in its manual and what I saw during last 3 servicing visits since '07 there was no sign of separate o/h stat, seems pretty 'dumb' - i.e. I only see now (from a frontal look) thermocouple cable, and thermostat control box with adjustment.

I'm not yet pre-judging the chap's competences as unfortunately, instead of popping round for a look, is currently waiting on a thermocopule (Said it's cheapest part and let's start there... plus admittedly my initial theory may have influenced his).

I hope once he does come with or without thermocouple, he can be diverted away from that and looking at the other ideas - certaily asd sounds very plausible, but until the explanation I received last night, couldn't see the connection with the long burn vs. short burn (hence assuming boiler overall temperature) and the cutting off of pilot light.

So currently, just to summarise as it may be of help to others I guess (there are apparently thousands of these old boilers around in just my county):

- doesn't seem to have o/h stat just adjustable boiler stat
- latter may be gone as it doesn't make any difference to water / radiator temperature (although if it only changes let's say 70 degrees to 75, then I guess both feel piping hot to my hand... so could be false alarm)
- it should only cut out main burner, however we have pilot light cutting out *right after* main burner goes out, IF there was a long proper burn
- the first thing that cuts is house thermostat, then after few seconds pilot light clicks out ==> first suspicion was related to thermocouple , for whatever reason incl. ventilation, deciding that pilot is not there hence safety cuts out
- ventilation etc. was measured on last visit, but whether something changed now, not sure - it never decides to cut out during burn , I would expect a fatal airflow problem to lead to something prior to normal ending of the burn

As soon as I have any more info (I hope first I manage to book him in... finally), will let you know - thanks again

 

[palmyra]

Quick update- probably by end of this week will be looked at.
In the meantime, has to be re-started every time it finishes a burn - few more phone conversations concluded that it might be an 'adjustment' of the thermocouple relative to the flam in case it got moved during last servicing somehow. It certainly started to play up right after that was carried out.

 

[Agile]

The boiler stat should adjust between about 60-85° approx.

According to your info then it is faulty and RGI whould replace it.

Has he measured the gas pressure at the meter with a fast response gauge at the point of burn ceasing?

Sometimes the meter regulator overshoots and this can kill pilot lights. Its rare though as the gas in the pipe will act as a buffer store.

Tony

 

[palmyra]

Thanks - last week when servicing was done, only measured the gas pressure at the boiler measurement point. So will suggest this, too - from visual assessment, can't see pilot light change in the short (5-10seconds) time period between burn ending and pilot clicking off, but this is something that can drive one nuts (or at least start imagining things).
I see the 'safety' part of the pilot, as I can make out the lateral flame and almost enveloping the thermocouple tip, but not quiet (if I look at a neck breaking angle through the monitor window). Interestingly it doesn't look different prior to burn and after, so very subtle changes could make a difference probably.

 

[palmyra]

Hi,

quick update - had the visit today and cleaned gas injector for pilot light, also the engineer said that he adjusted a bit the thermocouple position relative to the flame, as it was barely touching even on maximum setting for pilot light gas flow.
So explanation was that it may have been enough for a while but after a burn the changed air flow etc. due to everything being hot around it could have been enough to alter it so it wasn't enough to keep thermocouple happy.

At the moment it's working OK and will "test" it for a while.

 

[SteveB100]

Hi - I realise this post is quite old - but I seem to have the same problem - same BBU Glow Worm 45 , following a service & the engineer doesn't seem to have a clear idea of a fix.

If the original poster is stilll about - did the fix work long term? Does anyone know how to "adjust a bit the thermocouple position relative to the flame"? as described.

Has anyone else come across this problem and can offer a fix? Prior to the service the pilot has only gone out two or three times in the last 15 years, so it looks like something that has been distturbed during the service.

 

[Agile]

Hi - I realise this post is quite old - but I seem to have the same problem - same BBU Glow Worm 45 , following a service & the engineer doesn't seem to have a clear idea of a fix.

I think we can assume the adjustments sorted out the OP's problem.

We cannot tell you how to do gas adjustments as that has to be done by a gas registered enmgineer. They can ask in a special part of this site.

Its always difficult when someone is employed to do a service and ends up causing a fault and being unable to sort it out.

The best suggestion I can make is that you discuss the problem with him and if he cannot solve it then he returns the service fee and you get another engineer to sort it out. We have a contributor to this forum in Herts.

Tony

 

[palmyra]

Apologies for the 'silence' in terms of longer term behaviour after the adjustment happened. Reason is that I changed the entire heating system after a couple of months, hence was not (and would not) be able to comment whether the slight mechanical adjustment of the thermocouple relative to flame works in long term.
It was certainly behaving for that remaining period of its life without any problem.

 

[SteveB100]

Thanks for the replies Agile & Palmyra.

The chap did come back the other day (after a bit of a chase) before I posted on here and he adjusted the heat input down as originally I had told him it was the larger GW 55 boiler (I subsequently found the model stuck on the bottom plate of the boiler) and the hot water was getting really hot since the service so I thought maybe when the pump stopped running the hot water in the boiler being static then tipped an overheat over the top (I have since found there isn't one fitted from this thread). Any way this made no difference and after about 10 hrs the house heating timer turned off and the pilot was out again next morning. javascript:emoticon('').

I phoned him again and mentioned the manual pilot adjstment and injector clean and he was supposed to return this afternoon to have a look and fit a new universal thermocouple - "just in case". Any way he still hasn't arrived so looks like he has "forgotten" the appointment again (or isn't coming back).

Assuming he doesn't appear tonight or phone me tomorrow this leaves me with a bit of problem. I was thinking of buying a new Glow Worm 45 Thermocouple and a new thermostat (as the water temperature doesn't seem to cool down much even when the stat on the boiler is clicked just over the off position) and seeing if someone experienced from this forum could fit these (obviously I would pay the appropriate cost) and ensure that all is well. Has anyone any comments of this line of thought or is an experienced engineer (or knows a good one) in the Cheshunt area willing to take on a challenge and restore my faith. I am not sure if this forum has a section where an "engineer" could get in touch with me.

 

[expertgasman]

The chap did come back the other day (after a bit of a chase) before I posted on here and he adjusted the heat input down as originally I had told him it was the larger GW 55 boiler (I subsequently found the model stuck on the bottom plate of the boiler) and the hot water was getting really hot since the service so I thought maybe when the pump stopped running the hot water in the boiler being static then tipped an overheat over the top (I have since found there isn't one fitted from this thread). Any way this made no difference and after about 10 hrs the house heating timer turned off and the pilot was out again next morning. javascript:emoticon('').

I phoned him again and mentioned the manual pilot adjstment and injector clean and he was supposed to return this afternoon to have a look and fit a new universal thermocouple - "just in case". Any way he still hasn't arrived so looks like he has "forgotten" the appointment again (or isn't coming back).

It seems a little odd that you had to tell the RGI (?) which mdel it was!
I would advise against a universal Thermocouple, they are useless and don't always last until the next service. Best to insist on a genuine Honeywell Q309A (I'm fairly sure that is the right one), they don't even cost much more than a cheapo"

 

[SteveB100]

Just an update for anyone else whom has this problem & thanks to those who replied. The engineer did eventually return and to cover all the bases I had bought a replacement Thermostat and a Thermocouple from one of those boiler sites on the internet. I wathched whilst the chap changed these - he had to use a universal Thermocouple in the end as the replacement, although supposed to be the original part had the wrong size thread on one end. He also cleaned out the pilot injector light. Touch wood since it was done about 4 weeks ago it has been as good as gold - may even last another 15 years!