# Pilot light going out often...and furnace making a big "boom" sound



## fireguy (May 3, 2007)

you really need to contact a licensed professional to inspect your furnace. That boom could be a warning that you have problem. I am not trying to frighten you, but this "boom"could be serious, and needs to be investigated.


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## beenthere (Oct 11, 2008)

As above, it can be a very dangerous thing.
You may be having a delayed ignition.
Meaning gas is going into the furnace and not lighting when it should.

If the delay increases. It can be very very dangerous. As in deadly.


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## Beth777 (Jul 3, 2008)

Thanks for input.

Leaving the furnace off for now, chillin' out with a little tiny heater, trying to get furnace service. Life can never just be simple, can it?!


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## jehiatt (Dec 14, 2006)

For some reason the the pilot may not be close enough or high enough to the gas flow output on the burners to ignite the gas as soon as the gas valve opens the flow. The pilot is apparently stong enough to keep itself burning by the gas control valve. Maybe a draft is blowing the gas away from the pilot. Just possible!
A few seconds later the "on" gas that did not light immediately, accumulated greatly, and finally found the pilot flame. There is your boom. That was an explosion and it blows out the pilot. So you need an inspection of the pilot lighting or it could be rust flacks on the burner clogging the gas output right at the pilot area. Vacumn the burner tops and area anyway. If you do have a lot of rust make sure you inspect the burner chamber for cracks and leaks. lol


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## hvaclover (Oct 2, 2008)

jehiatt said:


> For some reason the the pilot may not be close enough or high enough to the gas flow output on the burners to ignite the gas as soon as the gas valve opens the flow. The pilot is apparently stong enough to keep itself burning by the gas control valve_*. Maybe a draft is blowing the gas away from the pilot. Just possible!*_
> A few seconds later the "on" gas that did not light immediately, accumulated greatly, and finally found the pilot flame. There is your boom. That was an explosion and it blows out the pilot. So you need an inspection of the pilot lighting or it could be rust flacks on the burner clogging the gas output right at the pilot area. Vacumn the burner and area anyway.


Draft blowing the gas away from the pilot? New one on me.


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## jehiatt (Dec 14, 2006)

*I said it is possible!*

Maybe not probable. You can't make judgement until you solve the cause.
The pilots I worked on were always on the outer limit of the burners and open to air flow. 
Anything that will momentarily suck the gas away from the pilot flame like a small vent suction or a cracked heat exchanger small suction can give the gas time to build up. A dislocated pilot tube is another. That's all it takes to cause an explosion. 
Finding the problem is always the main problem. Repairing it is the easy part.


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## hvaclover (Oct 2, 2008)

jehiatt said:


> Maybe not probable. You can't make judgement until you solve the cause.
> The pilots I worked on were always on the outer limit of the burners and open to air flow.
> Anything that will momentarily suck the gas away from the pilot flame like a small vent suction or a cracked heat exchanger small suction can give the gas time to build up. A dislocated pilot tube is another. That's all it takes to cause an explosion.
> Finding the problem is always the main problem. Repairing it is the easy part.



Yeah:thumbsup:~snicker~


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## fireguy (May 3, 2007)

jehiatt said:


> For some reason the the pilot may not be close enough or high enough to the gas flow output on the burners to ignite the gas as soon as the gas valve opens the flow. The pilot is apparently stong enough to keep itself burning by the gas control valve. Maybe a draft is blowing the gas away from the pilot. Just possible!
> A few seconds later the "on" gas that did not light immediately, accumulated greatly, and finally found the pilot flame. There is your boom. That was an explosion and it blows out the pilot. So you need an inspection of the pilot lighting or it could be rust flacks on the burner clogging the gas output right at the pilot area. Vacumn the burner tops and area anyway. If you do have a lot of rust make sure you inspect the burner chamber for cracks and leaks. lol


Good call, I do not work on gas furnaces, only commercial gas appliances. I have seen something similar on ranges and ovens. A range does not "boom" but I have had ovens do something similar. Grille pilots are sometimes hard to light. I have had grilles where only one pilot will light. In that case, I light the one pilot and then turn on on burner at a time, each burner will go "whoosh" as it lights, then I turn on another burner. Normally, that lights the pilots. Somtimes the pilot flame needs to be adjusted so the pilot flame will be in the path of the gas as it comes out of the burner. Can you adjust the amount of gas coming out of the pilot? Can you adjust the thermocouple so it is in the flame? There should be approximatly 1/3 of the thermocouple in the pilot flame. The tip of the thermocouple should glow red, not blue. The pilot may be dirty, can it be cleaned? or replaced. You might try blowing through the pilot tube also, I have seen them obstructed. Wipe off the tip of the thermocouple, after it has cooled. For a little thing, it gets hot! 

Beth777, all we have done is to give you some options, I still think it is time to call a professional. You might try wikipedai for more info. 

hvaclover, if you have nothing to contribute except snickers, keep it to yourself.


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## fireguy (May 3, 2007)

A little more info, courtesy of a plumbing board. Someone else has a furnace that makes noise on ignition. 

There is a carbon igniter that makes a noise on ignition. A pilot is queit on ignition. So, now what type of ignition do you have? And do not ask me what a carbon ignitor is, I do not know.


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## beenthere (Oct 11, 2008)

Is it fixed yet.


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## hvaclover (Oct 2, 2008)

fireguy said:


> Good call, I do not work on gas furnaces, only commercial gas appliances. I have seen something similar on ranges and ovens. A range does not "boom" but I have had ovens do something similar. Grille pilots are sometimes hard to light. I have had grilles where only one pilot will light. In that case, I light the one pilot and then turn on on burner at a time, each burner will go "whoosh" as it lights, then I turn on another burner. Normally, that lights the pilots. Somtimes the pilot flame needs to be adjusted so the pilot flame will be in the path of the gas as it comes out of the burner. Can you adjust the amount of gas coming out of the pilot? Can you adjust the thermocouple so it is in the flame? There should be approximatly 1/3 of the thermocouple in the pilot flame. The tip of the thermocouple should glow red, not blue. The pilot may be dirty, can it be cleaned? or replaced. You might try blowing through the pilot tube also, I have seen them obstructed. Wipe off the tip of the thermocouple, after it has cooled. For a little thing, it gets hot!
> 
> Beth777, all we have done is to give you some options, I still think it is time to call a professional. You might try wikipedai for more info.
> 
> hvaclover, if you have nothing to contribute except snickers, keep it to yourself.



I'm sorry you were offended. Honestly was not my intention.
Was just giving a light hearted ribbing.
But the truth is I had a hard time with the second statement JEHIATT made made about all the pilots he worked on being exposed to external air currents. 

Just sounded like it was being made up because no standing pilot appliance used for heating is designed that way. Because if they were they would be exposed to ambient air (not being inside heat excanger) and would not be close enough to burner to litght the gas when it comes into the burners.

I think the sticking point is that a furnace burns under draft from the chimney and grill and ovens do not.

Point is we want to give ACCURATE info to our DIY posters and not cause them any harm.

So saying *BETH 777 IT SOUND LIKE YOU HAVE PATIALLY PLUGGED BURNERS.

tHE PILOT MIGHT NEED ADJUSTING BUT I DON'T THINK IT IS THE MAIN CAUSE OF YOUR PROBLEM.

iF YOU COULD POST THE BRAND AND MODEL AND HOW OLD IT IS IT WOULD BE HELPFUL.

iF YOU CAN TURN OFF THE GAS AND REMOVE THE BURNER IT IS A SIMPLE MATTER OF ELBOW GREASE AND A STEEL BRUSH TO SCRUB THE BURNERS CLEAN,*

If the problem persists after cleaning than you need new burners.


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## plunked (Dec 19, 2008)

I am having the same problem with my Rheem gas pack. I removed my burners and as I was inspecting each heat cell ( heat exchanger)I came across a large crack. I Removed all three cells and each one had either a crack or hole. I replaced each one with a new one and put it back together. When I returned the unit to service it continued to flame out at start up. The ignitor would fire a couple more times and then the accumulated gas would ignite with a large boom. The pilot tube was aimed towards the cross burner and this unit has a spark ignition system with no separate flame sensor. I moved the pilot tube so the the flame was aimed directly at the spark ignitor but no improvement. Burners apeear to be clean. Cross burner looks good. Ignitor seems to have a good spark. Large amounts of gas builds up when it's trying to light. Have not found the problem yet.


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## beenthere (Oct 11, 2008)

New cells may not be sealed right.
So gas may not be drawn across ignitor correctly.


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## plunked (Dec 19, 2008)

Thanks beenthere. I spoke with a service man and he said the same thing. I bought some High temp caulk and will attempt to make a better seal. Should I fabricate new insulated gaskets or do you think the caulk will be a good enough seal? I may try and tighten the screws before I attempt to break the whole thing down again though just in case the cells aren't seated well. I also bought a new ignitor board and the cover has melted after one day of use. The old board was melted in the same way and there is no heat shield for this board. Should I fabricate a heat shield? 

Thanks for replying


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## beenthere (Oct 11, 2008)

You can use either.

I prefer to use high temp gasket material with the caulk.

But, it is expensive.


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## 4just1don (Jun 13, 2008)

Anything is possible. I used to live where the furnace banged when lighting too,,,but never blew out the pilot. When looking at the furnace burning,,,not all the burners were burning outside where they belonged. Some were burning inside the burner tubes. Propane guy fixed it one time,,,but quickly did same thing. Said it wasnt to be worried about,no problem. my guess is it was old enough they burned thru and rusted out. basement had standing water in it alot of the year


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## plunked (Dec 19, 2008)

*Re: Furnace Problem*

Here is the latest, I've removed my new heat cells to seal them with high temp sealant. One of the cells did seem to be loose so I made sure they were all very tight and well seated against the manifold. When I returned the unit to service It starts up fine with the cover off. When I put the cover on and seal it up correctly I then get a tripped rollout switch on startup and I have to manually reset it. Seems like this is where it all started. I also remembered using one of those new allergy filters this summer that has the fabric type filter material( or whatever you call it) Vs. the inexpensive fiberglass filter that I used to use. I found that this restricts the air flow through my return a good bit. I'm thinking that maybe this is where it all began. I'm going to replace the roll out switch today since it has been activated so many times by now. If this doesn't get it then I think maybe the gas valve may need to be adjusted. I've replace the heat cells, cleaned the burners and the spark ignitor rod, and replaced the ingnitor box, which still seems to be okay even though the cover has melted a little. ( I still get the heartbeat or pulsing green light and it operates okay so I think its okay) Other than that every thing cycles as normal, it's just tripping the flame rollout switch at start up. Thanks for any comments on this issue


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## zaskar (Jan 22, 2011)

Fireguy,

I'm having a similar problem with a commercial Southbend Range, the right oven pilot light stays lit. But I noticed that it's making a boom, I assume from gas filling up in the oven, but not igniting. Do you have any advice on what you think it might be since you mentioned you work on commercial appliances. I've been watching it to see if I can figure out what is wrong. The left oven has no problem. Thanks for anyhelp.


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## hvaclover (Oct 2, 2008)

zaskar said:


> Fireguy,
> 
> I'm having a similar problem with a commercial Southbend Range, the right oven pilot light stays lit. But I noticed that it's making a boom, I assume from gas filling up in the oven, but not igniting. Do you have any advice on what you think it might be since you mentioned you work on commercial appliances. I've been watching it to see if I can figure out what is wrong. The left oven has no problem. Thanks for anyhelp.


Old thread guy.

Post a new thread or no one will find you here.
Good Luck


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## jehiatt (Dec 14, 2006)

One thing for sure is the pilot flame needs to be tall enough and real close to the first burner or supply line outlet to all burners. For sure and for some reason. the gas flow inputted is not hitting the pilot immediately. possibly the gas is being sucked up by an attic fan, vent fan, AC or Heater. I have seen some that when the main burner comes on the line pressure drops and the pilot goes almost out. Check that also.
look fer it!


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