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  1. #1
    I have An ArcoAire (Snyder General) HVAC:
    Model #:GUA080A016-IN
    Serial #0000246426-P05-0106

    I have a flame rollout in the #2 combustion chamber that begins at 2-3 minutes after the main blower starts.I was having a flame rollout in both #2 and #3 that began immediately after ignition. I had the unit professionally cleaned/inspected, which eliminated the #3 problem. The tech found no cracks in the exchanger. The flue is clear. There is venting at the #2 exhaust. The combustion fan is running and appears strong. We even tried removing the baffle at the top of the exchanger. Still, the tech was unable to diagnose the problem and recommended replacement. Any suggestions?

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    33,398
    The GUA is forced draft. You have to have the burner box cover securly on when running the furnace. If not, you will have rollout. Still, seems funny it is only 1 cell. Could be a crack the tech isn't finding.

  3. #3
    Join Date
    Oct 2004
    Location
    The "Burgh"
    Posts
    1,255
    I agree with John. Further inspection of the rollout condition is needed, especially since it is not an end burner, but a #2 burner rollout. Are we sure we are not overfiring ?

  4. #4
    Thank you. I'll check. But wouldn't overfiring affect all the chambers?

  5. #5
    Join Date
    Apr 2003
    Location
    Iowa
    Posts
    763
    does that model have a sealed burner cover? if so tape off the intake and exhaust pipes..... hook your magnehelic up to the burner box pressure port....cycle fan off and on with the switch....if you get a reading you have a hole in a heat exchanger....

  6. #6
    Join Date
    Mar 2003
    Location
    North St Paul MN
    Posts
    858
    Does this unit have the outside combustion air intake connected to the draft motor? If it does, disconnect it. These units had a tendency to get rusty burners due to humid air from the intake. Rusty burners=incomplete combustion=sooty heat exchanger=flame roll-out.
    I'd rather have a bottle in front of me, than a frontal lobotomy.

  7. #7
    The unit was overfiring. The manifold pressure was at 4.0", and btu/hour was 96k (by meter check). Nameplate is 3.5" and 80k btu/hour. I eliminated the rollout problem by reducing the pressure to 3.4, which resulted in a btu/hour of 84k. My question now is, which is more important, manifold pressure, or btu/hr?

  8. #8
    Join Date
    Jan 2005
    Location
    Gilroy, Calif
    Posts
    188

    Hmm

    You called it. Rating on Gas control valve should say 3.5" W.C to 4.0" W.C. Manifold pressure + orfice size should equal Btu rating. RTd 80kBtu fnd at 94kBtu. Wow that's 20% overgassed. Did you check the heatexchanger for soot?

  9. #9
    Yes it was very sooty and had to be cleaned. Thanks everyone for your help!

  10. #10
    Join Date
    Oct 2004
    Location
    The "Burgh"
    Posts
    1,255
    We all guess lucky once in a while !

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