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  1. #1
    Join Date
    Feb 2013
    Location
    Tri-Cities, Ontario
    Posts
    8

    Lennox RTU, manifold pressure

    Working on a GCS16-653-125-3J. Im not to familiar with these units. My issue is my manifold pressure jumps up and down. From a high of 2.8" to just below 1". I have a rock steady inlet pressure of 6.6"
    Any help would be great.
    Thanks

  2. #2
    Join Date
    Feb 2012
    Location
    Ottawa, Ontario Canada
    Posts
    40
    Gas valve.... dont think those rtu's have slow opening gas valves but could have crap in the gas valve. I'd replace.

  3. #3
    Join Date
    Feb 2013
    Location
    Tri-Cities, Ontario
    Posts
    8
    This is the 2nd valve, original valve did the same thing.

  4. #4
    Join Date
    Oct 2011
    Location
    Chicagoland Area
    Posts
    4,322
    I believe 2.8" lowfire and 3.7" wc highfire is what you should have
    Officially, Down for the count

    YOU HAVE TO GET OFF YOUR ASS TO GET ON YOUR FEET

    I know enough to know, I don't know enough
    Liberalism-Ideas so good they mandate them

  5. #5
    Two stage valve?

  6. #6
    Join Date
    Feb 2013
    Location
    Tri-Cities, Ontario
    Posts
    8
    Its single stage, Manufactures specs call for 2.7".

  7. #7
    Join Date
    Jul 2005
    Posts
    5,153
    Sounds like you may have a manometer issue. Cracked hose?

  8. #8
    Is that model one with the " gun type" burner, where the inducer mounts with the gas line and blows the flame into the heat exchanger?

  9. #9
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,365
    A little off topic but I hate gcs units.

    Sent from my SGH-T999 using Tapatalk 2

  10. #10
    Join Date
    Feb 2013
    Location
    Tri-Cities, Ontario
    Posts
    8
    manometer is six months old and my hoses are fine. The same hose and meter was used to test all my other pressures at the same time.
    The burner is kind like an in-shot, the heat exchanger is kind of diamond shape to tubular to combustion fan. If that makes sense?

  11. #11
    Join Date
    Sep 2008
    Location
    rensselaer,ny
    Posts
    112
    what kind of issue you having with unit , I had one giving me problems it was heat exchanger ,new exchanger replaces the one inshot burner design.

  12. #12
    Join Date
    Feb 2013
    Location
    Tri-Cities, Ontario
    Posts
    8
    I'm getting low temp rise, 15 - 20 deg F. Manufactures specs 40 - 70 deg F. Indoor fan speed is ok, im not getting any outside air in, and i tried to clock the meter, i couldn't tell the scale of the dail due to the age of the meter. My guess is that im only burning 61000 btuh. Units input is 125000.

  13. #13
    Join Date
    Feb 2006
    Location
    USA
    Posts
    4,365
    And the inlet stays at 6.6" the entire time?

    Sent from my SGH-T999 using Tapatalk 2

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