Discuss Pilot light going out? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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M

mcniven

Alright team

Went to a floor standing old boiler today and what's happening is the pilot light is going out after about 5 minutes of the boiler being u
And running, not just the burner going out but the full pilot.

Does this still point towards thermocouple even although it stays lit for the first 5 minutes?

Thanks man!!
 
Only me, but would renew thermocouple and see what happens.

Is there an FSD (tube type) fitted, they can put the pilot out though.
 
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I've not opened her up yet just relit pilot got a call as I was driving home :(
 
Check pilot is touching tc, if not check pilot injector, check when main burner lit if it's being pulled away from tc, if ok check tc then tc interuptor if fitted, gas valve. Has it go o/heat stat ? Is pump running ?
 
An interruptor is an overheat 'stat that acts on the thermocouple, so if the sensor operates due to the appliance overheating or sometimes spillage of POC then the thermo-electric valve drops out shutting off the gas to the main burner and pilot.
 
its a bi-metalic strip on thermocouple lead, when overheated it will interrupt the circuit and TEV will shut
 
Mountain man how does it detect POC?

So most likely because the burner is staying a light for 5 minutes really tells me that the thermocouple is working and that most likely it's an overheat issue and on this type of system that points at the pump. Which...... Could be anywhere!! :D
 
Is it open flued or ballance flue mcvens? A good t/c should hold for about 20-30 seconds. if it's clicking off pretty fast that'll be a poor flame, t/cupl or gas valve in that order .... May also be visceation due to blockage in flue or heatex/flue rotten .... there's a few things to try out :)
 
Mountain man how does it detect POC?
:D

You'd most likely to find this on an Open flued appliance but If the sensor is positioned at the vent of the down draught diverter then the heat from the POC's would cause the sensor to reach a sufficiently high temperature to trip.
 
I'm just off the phone to ideal and he said the Mexico doesn't really have that much too it...


And he's told me that if not the thermocouple it's going to be the gas valve. He said that stat we spoke about is only in the sealed systems.

He told me there's not much to a ideal Mexico parts wise that's where his answer is from.
 
He's right, there's not much to a Mexico.
Is the flue and air intake clear, is the pilot stable whe the burner is alight?
 
What do u think diamond

Visual first on the pilot will tell you a lot. Also visual on lighting up and running. watch see what is happening to the pilot flame! A soft pilot flame can be pulled off the t/c by the burner once alight! ... Nice blue flame enveloping the t/cupl! If you're taking the burner out might as well replace the t/c and clean the pilot injector TBH! Can't be much mcnvens.? Stick to the simple stuff first, watch to see what's going on then decide next course of action! imho
 
When flame goes out (extinguishing pilot as well) can you hear thermocouple magnet release afterwards?

If you can't hear it then it may be that thermocouple is shutting down during the five minutes of burn, then closing gas valve to main burner.

that points at the pump. Which...... Could be anywhere!! :D

Top tip, if you look for a pair of pump valves then the pump is usually between them. Hope this helps.
 
Haha jap

Ok well batter on and see how it goes, always feels like diving into something new when you come across a boiler never worked on, takes you out of your comfort zone when it's not a shiny beautiful combi inside lol...

As I said aswell , I explained the ideal rep about should the pump be faulty wouldnt this cause the burner and pilot to go out due to overheat he said no, this would only cause burner to go out keeping pilot on because it doesn't contain that other stat we mentioned

He said the gas is being cut off somewhere, and on this boiler the only place is the gas valve or tc
 
Haha jap

Ok well batter on and see how it goes, always feels like diving into something new when you come across a boiler never worked on, takes you out of your comfort zone when it's not a shiny beautiful combi inside lol...

As I said aswell , I explained the ideal rep about should the pump be faulty wouldnt this cause the burner and pilot to go out due to overheat he said no, this would only cause burner to go out keeping pilot on because it doesn't contain that other stat we mentioned

He said the gas is being cut off somewhere, and on this boiler the only place is the gas valve or tc

Just always keep 3 thermocouples on the van and change um every time you have any doubt, there dead cheap and it rules it out on the 1st visit, then if you get a call back you can be pretty sure its the gv
 
Haha jap

Ok well batter on and see how it goes, always feels like diving into something new when you come across a boiler never worked on, takes you out of your comfort zone when it's not a shiny beautiful combi inside lol...

As I said aswell , I explained the ideal rep about should the pump be faulty wouldnt this cause the burner and pilot to go out due to overheat he said no, this would only cause burner to go out keeping pilot on because it doesn't contain that other stat we mentioned

He said the gas is being cut off somewhere, and on this boiler the only place is the gas valve or tc

The best advice I got when I was younger because I couldnt fault find on combi's are

When you come accross a new boiler take the case off and have a look around before you start and make a mental note of what parts you see all boilers work the same just the parts look different and some have extra parts. And the only difference between a combi and heat only is that your pump, 3 port, HW stat is in the airing cupboard not the boiler.
 
Job done

Removed burner and cleaned renewed thermocouple old one looked a little battered

Kicked boiler on 20 mins later still burning away. Only logical answer I have is that when burner came on it may just of slightly pulled the flame off tc just slightly enough to cut her off after a couple mins.

Thank you team!
 
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