burners dont always light ???


  #1  
Old 03-15-08, 03:42 PM
D
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burners dont always light ???

Hello, new to this forum but have been dealing with this for several years now. My forced air furnace(8years old) Rheem model#: FGPJ-05EAUER will begin to ignite normally (right side burner with igniter ) but the left buner(with the flame sensor) sometimes will not follow and the system will shut down. If I blow into the left burner after the right side ignites, the left one will then ignite and will cycle normally. Do I have exhaust flow issue? Why doesn't this happen all of the time? I've dealt with this for sevral years because it eventually lights but sometimes it wont and go into lockout for an hour. I've cleaned and replaced the flame sensor but this did not solve the problem. I've ruled out the flame sensor because the second burner doesn't even ignite for a second before it shuts down. Can anyone shed some light on this?? Thank you

Dave
 
  #2  
Old 03-15-08, 11:45 PM
M
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Hi Dave,

If your looking at the burner assembly kind of from the top down, you know like where the flame is jetting out, you will see the inch or two of spacing from one jet to the next.

This is actually two thin pieces of sheet metal that are very close together.



Not a very good picture but it will have to do...anyway notice as it gets close to the jet section that the sheet metal sort of flares out, well it actually is leaving a very small spacing between the sheetmetal on each side of the jet open and the gas escapes out each side and lights.

If you have 3, 4, or 5 burners or whatever the gas will trace out and light, then light the next trace wich lights the second burner, which lights it's next trace and so on till it gets to the last burner.

...sometimes, however, you will get some carbon build-up in that tiny gap between the sheet metal and the only way the next burner will light is if the gas just builds up so much around that jet that it finally catches from the first jet and will sometimes POP and light. Sometimes it will time out before it gets that far.

If the traces aren't lighting some times a quick fix is to hold a screwdriver by the tip and lightly bang the sheetmetal close to the traces (don't hit it too hard!) to knock the carbon loose. You'll see the flame changing color if you do it while it's running and it's burning the buildup as it get loose. sometimes it's bad enough though you have to take the burner assembly out and take a wire brush to it. Not always though.

...as an after thought, make sure the gas shut-off valve is all the way open and your not getting partial pressure. Let us know how it goes!

Michael
 
 

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