Old furnace - burner shoots flames

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  #1  
Old 03-28-04, 03:48 PM
Bruce Mencer
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Question Old furnace - burner shoots flames

Hi,

I have an old furnace in a cabin that is propane fired. We normally keep the heat turned down to 50 during the winter as we don't visit it often. Started having trouble this winter. Went down in January and the pilot light was out. Relit with no problems. Furnace cycles on and off very frequently but for less than one minute on each time.

Went down in February. Same thing. Went out and got a thermocouple and a new thermostat to install.

In March, went down to install the items. Again had to relight the pilot. When I turned up the thermostat, the burner kicked on, went "swoosh...swoosh" each time swoosh flames shot out two to three inches beyond the pilot light hole. Shut it off, waited an hour started up again. Same thing.

I do not know what brand it is. It is mounted in the wall between two studs. Has the burner/pilot/valve at the bottom and the fan on the top.

My question is...could this be a cracked burner and can they be replaced or should I start looking for a new furnace of some sort?


Any info is appreciated.

Thanks

Bruce
 
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Old 03-28-04, 04:21 PM
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In March, went down to install the items. Again had to relight the pilot. When I turned up the thermostat, the burner kicked on, went "swoosh...swoosh" each time swoosh flames shot out two to three inches beyond the pilot light hole. Shut it off, waited an hour started up again. Same thing
Need more info here . Did you run out of gas anytime ??

When was the last time the burners where cleaned out and looked at. Is the regulator ok out side and working right for 11" W/C at the burners. Any little spiders up there in the venturi tube of the burners

My question is...could this be a cracked burner and can they be replaced or should I start looking for a new furnace of some sort?
Clean the burners good, Check the regulator for 11" W/C and see what it will do. Vent hole open on regulator outside. Did you clean the pilot out good also when you put the T/C on ?
The tstat dont have anything to do with this . Cracked heat exchanger should light ok then blow out the flames when the blower came on. ED
 
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Old 03-28-04, 04:38 PM
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Hello: Bruce and Welcome to the Do-It-Yourself web site.

Furnace type is vertical wall mounted unit. Part of it is inside the wall between the studs while the other part of it's depth is outside the wall. Vent inside wall and not visable.

The unit can have a spider inside the burners venturi. The venturi is the part of the burner between the burner head where the flames come out and the other end is on the orifice which is on the gas valve. Hope the description is understood. If not will try to explain it in another way.

The spider web will be in the venturi and or can be in the orifice. Orifice is on the gas valve where back end of the burner venturi is. Chances are spider may be the problem.

Another possiblity is air in the gas lines. Especially when left unused for some period of time. Can be but may not be. Just another possibility.

You will also need to inspect upwards into the firebox. Use a bright flashlight and a hand held mirror. Mirror facing upwards resting on burner or near front of burner.

Flashlight shines into mirror. Adjust mirror as needed. Looking upwards into firebox for any unusal obstructions like siper webs, mice nests, etc.

Might have a blocked exhaust vent but not as likely since the unit has a built in downdraft divertor. Downdraft divertor is the hood like device near the top of the firebox behind the front louver.

The problem description is the key words...swoosh...swoosh. Thanks for including them. Tips we needed to know...

Suspecting there is either a lack of air flow in the firebox or a problem with the gas valve, pressure to it, etc. Problems which can best be determined once the usual and minor detail checks are done.

Kindly use the reply button to add any additional information or ask additional questions. Attempt the repair solutions or correctional method(s) provided first. Than update the question.

Check back on your question several more times. Other professionals and members posting replies in this forum topic may offer you additional advice, suggestions and or repair methods.

Regards & Good Luck. Sharp Advice.
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Old 03-28-04, 04:52 PM
Bruce Mencer
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Thanks for QUICK replies

I am glad I found this site. Quick replies and advice from both are appreciated. At least now I have some direction.

Thanks

Bruce
 
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Old 03-29-04, 08:21 AM
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Hi: Bruce

Another thought and possibility just came to mind....

If the pilot flame is not all blue and hot, clear the pilot assembly to remove any dust and lint. A can of compressed air chemical used for cleaning computer keyboards works well.

Even if all appear well do it anyway. The swooshing also indicates a delay in burner ignition which may be cause and is likely caused by a weak pilot flame and or one not hot enough to light the burner.

A weak pilot flame may have the ability to keep the pilot flame on but not be sifficient to light the burner flames when the gas valve opens. Thus the swooshing of flames results.

Also insure that the pilot flame is either facing the burner or points over the burner, depending on it's setup. Usually two flames. One keeps the pilot generator hot while another pointed flame faces over the burner or point upwards to the burner.

Kindly excuse me for 4getting to mention these other possibilities in my first reply. I just may have been out of the field too long or a "Senior Moment " was in progress at the time...
 
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Old 04-18-04, 11:45 AM
Bruce Mencer
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More info

Hi again,
Well, I changed the thermocouple and the t'stat (figured it couldn't hurt), cleaned the area around the pilot light, cleaned the area around the blower. Thought I had it fixed as first indication was that it worked properly. Last couple days have been unseasonably warm (mid 70s) so until last night it never came on.

Well...last night it clicked, and again...whoosh, whoosh shooting flames each time and it blew out the pilot. It was late at night so I just shut it down.

This morning I reread the posts and tried to see with the mirror. I cannot see past the burners as they are mounted at the bottom of the firebox (?). I also don't see a way to check or clean the burners.

I did find out that the furnace is a "Forsaire" by Williams.

Any advice is appreciated.

Thanks

Bruce
 
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Old 04-18-04, 12:38 PM
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Dont know the furnace. But the burners do come out to clean on the gas furnace. With power off try a shop vacuum on them and see. Make sure that lighter strip in the front there is clean all across the burners
LP when was the last time you had the pressure regulator checked out for 11" W/C. At any time have the burners lit down in the Venturi tube.Check the regulator vent hole see that it is clear out side there
This morning I reread the posts and tried to see with the mirror. I cannot see past the burners as they are mounted at the bottom of the firebox (?).
Take a wire coat hanger straighten it out and see if you can run it up in the furnace over the burners and get up to the draft hood

ED
 
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