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Old 04-15-2009, 05:03 PM   #1
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Pilot flame...too big?


Hi All,
I have been struggling with my Bryant 394GAW furnace (20+ years old) over the last couple of days. Pilot would light ok and then burners would light ok, but then they would go out after ten seconds or so. That would repeat a time or two until the blower would finally come on. After much online searching, I ended up cleaning and sanding the flame-sensing pilot assembly as well as the pilot gas tube. Seems to be working much better now, but the pilot flame itself is now MUCH bigger than it was before.

Before the cleaning it was maybe a one-inch, easy-going flame, all nice and blue like it's supposed to be. After the cleaning, it's still nice and blue, but is now at least three-inches long and a little more jet-like. Is this normal for this type of furnace? Again, the sequence of operations seems to be fine, and everything is working better than before.

I am fairly certain that I didn't inadvertantly adjust or change anything else...just the cleaning.

Thanks for any input.

Tim

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Old 04-15-2009, 05:48 PM   #2
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Pilot flame...too big?


You either dropped the pilot orifice or enlarged the orifice opening.

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Old 04-15-2009, 07:05 PM   #3
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Pilot flame...too big?


You did something.
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Old 04-15-2009, 07:42 PM   #4
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Pilot flame...too big?


I know that I "did something," I just don't know if I did something wrong, or simply cleaned out a dirty orifice and the flame is now the way it should be.

Is there a "right" size for the pilot flame? There is actually some discoloration on the wall of the heat exchanger, adjacent to the pilot, as if the pilot flame used to be this way.

I guess I am wondering...is it wrong? And if so, can I adjust something like that somehow? Can I "raise" the orifice if I dropped it? Or do I need to replace the pilot/ignitor assembly?

Thanks again.
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Old 04-15-2009, 07:54 PM   #5
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Pilot flame...too big?


Did you put the orfice in upside down.

You can adjust the amount of gas going ot it.
But first, you have to see if you did anything to the pilot that needs corrected first.
Did you ream the orfice out.
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Old 04-15-2009, 08:02 PM   #6
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Pilot flame...too big?


If you reamed that orifice too large than adjusting the pilot press is not going to cure your problem,

Too big an orifice with too little gas is gonna make a dirty flame.
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Old 04-15-2009, 08:10 PM   #7
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Pilot flame...too big?


I never even took the orifice itself out of the assembly, so I know it is not upside down. I did use a straight pin to try and clean out the orifice, although "reaming" would be a pretty strong word for what I did. I basically just stuck the pinhead in there and twisted it a little bit to clean the hole. The pin would not go throught the hole, and I didn't force it, but I used a wee bit of pressure just to clean out any scuzz. Are they THAT precise?
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Old 04-15-2009, 08:54 PM   #8
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Pilot flame...too big?


Yes they are.
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Old 04-15-2009, 09:02 PM   #9
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Pilot flame...too big?


Maybe I put too much into the cleaning. Would you say that if I can get a nice soft blue flame by reducing the gas a bit, that would be okay? I would rather not replace it if I don't have to, but I will if that's the only way.

Are you familiar with the ignitor/pilot assembly I am talking about? Is there a guideline for how high the pilot flame should be?

Thanks for all your help,
Tim
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Old 04-15-2009, 09:13 PM   #10
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Pilot flame...too big?


The pilot flame should engulf the top 1/3 of the thermocouple only.

You need a new orfice.

If you lower the gas down, you won't get a good air mix.
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Old 04-15-2009, 09:36 PM   #11
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Pilot flame...too big?


There really isn't a thermocouple with this one, just the pilot assembly and the ignitor, so i'm not quite sure how big the perfect flame is.

It doesn't really matter, it's clear there's something wrong, I am going to go ahead and replace the assembly. It isn't worth the aggravation or the worry - bloody thing's over 20 years old anyway, it deserves a new part every now and then.

Thanks for your help!
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Old 04-15-2009, 09:55 PM   #12
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Pilot flame...too big?


beenthere, would you say this is a big safety issue, if it operates like this for a few days, until my new parts arrive? As I said, everything appears to be working correctly, if not better than before - the sequence is all correct, no false burner starts, etc. - there's just the large pilot flame.

Thanks
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Old 04-16-2009, 04:37 AM   #13
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Pilot flame...too big?


More of a waste of gas.

Has the potential to produce some excess CO.

Dangerous if it were to go out for some unknown reason and putting in all that excess gas, which won't always vent up the chimney.
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Old 04-16-2009, 06:56 AM   #14
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Pilot flame...too big?


Wonder if he has that old bryant 3 wire pilot assy ??
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Old 04-16-2009, 07:18 AM   #15
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Pilot flame...too big?


kenmac,

Yup, it's the old 3-wire pilot assembly.

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