Old Trane burner problem

[mprob]

I am working on a old standing pilot Trane BLU120E936B. The burners are in suprisingly good shape. There was some debris on them....like some white little foam balls???...some rusty powder inside them. They were'nt that rusty in the slots. So I cleaned them. It has four burners, and one of the middle ones will lite the length of the burner, then after a few seconds, slowly go out until it comes back to where there is a small ball of flame next to the crossover part of the burner next to the pilot. I adjusted manifold press from 2.5 w.c. to 4 in , recleaned burners, cleaned crossovers, adjusted pilot, checked orifice and it was clean. Any suggestions? BTW...the other burners are burning fine, and from what I can see my problem burner looks fine???

[socotech]

Nat or LP?

[fordrules]

If the "ball of flame" is by the pilot assembly, I'm guessing its either the pilot flame itself, or the pilot assembly is in the path of the burner flame and disrupting it. How big is your pilot flame? As far as the manifold pressure, 4.0 sounds more like a boiler setup than a furnace. If it is a furnace it should be 3.5 if this is a natural gas unit. Also check for Flame distortion on blower start-up if it is a furnace

[mprob]

Thanks to everybodies replies I was able to fix it. I had to take the draft hood off and and remove metal pieces inside hx. After cleaning and vaccuming out upper hx the burners were fine. This website rocks! Thanks guys.

[lynden]

I would check for s spider nest in the manifold. It sounds like that burner is starving for some reason.

[trintch9]

Check the orifice ther might be a retriction and adjust your manifold press to 3.5 w.c. Also your burner holes may still have build up off that white powder

[dgussler]

Is that part of the heat exchanger above that burner stopped up?

[gravity]

Make sure the ribbon isn't clogged. Make sure the burner orifice doesn't have a flake of metal stuck in it.

make sure that cell of the heat exchanger is clear.

very interesting call. hope you figure it out. let us know what it is.

[mprob]

How do you check if the cell of the heat exchanger is clear?

[gravity]

you could also have a big crack in that cell. does it do this when the blower comes on?

[rundawg]

How do you check if the cell of the heat exchanger is clear?

As gravity said, visual inspection.

Either remove the flue box cover or pull the burners, and stick an inspection scope in each cell.

At 25+ years old, and with the problem you are describing, my money is on the HX has been compromised.

I would also want to do a combustion analysis on that unit before I put it back into service.

[gravity]

light test. visual inspection. you may have to take off the collector box

[gravity]

Sorry to hi-jack.

Rundawg...Did u make the powerpoint of checking static pressure?

There is a thread in the tools. Guy wants to know how to check it.