Author Topic: Does anyone have any ideas why the exhaust stack fumes re-ignite? (Read 781 times)

Jim · « **on:** June 01, 2021, 07:22:50 pm »

This is my 4" gas fired boiler, does anyone have any ideas why putting a flame over the exhaust stack re-ignites ? Surely I would think that all the gas is combusting inside the boiler? Any thoughts why this is happening would be appreciated guys.

Stoker · « **Reply #1 on:** June 01, 2021, 07:33:33 pm »

The logical assumption would be that you are running too fuel rich in your mixture and need to be getting more air into the combustion chamber.

Jim · « **Reply #2 on:** June 01, 2021, 07:42:13 pm »

Quote from: Stoker on June 01, 2021, 07:33:33 pm

The logical assumption would be that you are running too fuel rich in your mixture and need to be getting more air into the combustion chamber.

Daniel nothings changed the way I use it same gas etc and I've had this boiler for years, its either always done this and I've just noticed it or its something has changed that I'm not sure of?

Stoker · « **Reply #3 on:** June 01, 2021, 08:19:06 pm »

Could it be that what you are seeing is actually gas from your torch, being deflected by the hot exhaust rising up your stack. I do agree that it looks like it really is unburned gas from your boiler's flue, but perhaps that is only how it looks?

Perhaps it's just a bad can of gas that you are currently using. Have you tried this experiment using any others?

Meanwhile, I'd mark your air vent collar position, and try adjusting it a little at a time, allowing for a bit more air into the mix and see if your situation changes noticeably. If you get to wide open without any change apparent, then I'd try the next size smaller orifice.

Raphael · « **Reply #4 on:** June 02, 2021, 01:51:02 pm »

Bonjour,
Stocker's last remark sounds correct to my opinion.
Did you smell the exhaust flow of the chemney. I was learnt that if your nose stings you is because the mixture is indeed too rich and it would then be advisable to raise the jet a little to clear the holes of the burner and let more air arrive

Jim · « **Reply #5 on:** June 02, 2021, 06:17:19 pm »

Quote from: Stoker on June 01, 2021, 08:19:06 pm

Could it be that what you are seeing is actually gas from your torch, being deflected by the hot exhaust rising up your stack. I do agree that it looks like it really is unburned gas from your boiler's flue, but perhaps that is only how it looks?

Perhaps it's just a bad can of gas that you are currently using. Have you tried this experiment using any others?

Meanwhile, I'd mark your air vent collar position, and try adjusting it a little at a time, allowing for a bit more air into the mix and see if your situation changes noticeably. If you get to wide open without any change apparent, then I'd try the next size smaller orifice.

Thanks Daniel, its Thursday morning here and I'm planning to spend some time having a look at what might be the cause.
Appreciate the thoughts.

Jim · « **Reply #6 on:** June 02, 2021, 06:17:51 pm »

Quote from: Raphael on June 02, 2021, 01:51:02 pm

Bonjour,
Stocker's last remark sounds correct to my opinion.
Did you smell the exhaust flow of the chemney. I was learnt that if your nose stings you is because the mixture is indeed too rich and it would then be advisable to raise the jet a little to clear the holes of the burner and let more air arrive

Thanks Raphael.

Stoker · « **Reply #7 on:** June 02, 2021, 06:58:35 pm »

One other thought here Jim ..... are you opening your gas valve all the way to the stop point every time you fire this boiler? If so, you might want to try turning the gas down a little, and then maybe the mixture will lean out and stop wasting gas out the stack. If that turns out to be the case, and you still want to use your gas control valve at max setting, then I would think the next smaller jet might be the way to go.

Raphael · « **Reply #8 on:** June 03, 2021, 12:11:15 pm »

Bonjour,
Stoker's idea is also another possibility. Please also take in account that, if you do not use a liquide phase gas, the tank will freeze and the pressure will drop after a fe minutes of use.
I was told that a good gas operating pressure is about 0,8 - 1 bar (10 - 15 PSI) and I know that I always start with 2,5 bar, pressure of the bottle during the refill.
To solve this problem, the gas regulator (détendeur, not attenuator = régulateur, the words are confusing in French) :

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Author Topic: Does anyone have any ideas why the exhaust stack fumes re-ignite? (Read 781 times)

Jim

Does anyone have any ideas why the exhaust stack fumes re-ignite?

Stoker

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Jim

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Stoker

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Raphael

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Jim

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Jim

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Stoker

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?

Raphael

Re: Does anyone have any ideas why the exhaust stack fumes re-ignite?