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Where's the water coming from.

Discussion in 'Commercial' started by Rather B Riding, May 10, 2017.

  1. Rather B Riding

    Rather B Riding Behind bars

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    608
    I just started this account about 1 year ago now. Good customer bad equipment installation. The first time I ever walked into this mechanical room I got oh shit feeling. So many things just visibly wrong. The the building is 18 years old customer had it redone from office space to a salon / spa in 2014. On the first time through I noticed evidence of water leak in a couple of the furnaces. Didn't think much of it because the hack install of this equipment is so bad. TXV s are outside the plenum and unwrapped. Now I'm finding evidence that its not the TXV dripping.
    There are 6 - 80% furnaces in this mech rm. All the flue pipes are Christmas treed into 1 -14" flue to the roof. Craziest thing you ever seen. I posted it when I first saw it. I'll post pics of the evidence I see but I have never seen them leaking. Need a little help determining cause and solution. I got my own ideas but want to see what some of you have to say. I can post more pics later.
    Thanks IMG_20170510_081036489_HDR.jpg IMG_20170509_123337761.jpg
     

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  2. Rather B Riding

    Rather B Riding Behind bars

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    608
    Hard to get good pics of the flue piping but all 6 go into 1 common flue. IMG_20170510_081315412.jpg
     
    oroy54 likes this.
  3. doc havoc

    doc havoc A cunning linguist

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    Is the common flue power vented? If not, my initial guess is that if only one or two furnaces are running, the flue is drastically oversized and flue gases are condensing in the flue pipes.
     
  4. Rather B Riding

    Rather B Riding Behind bars

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    608
    The 14" flue is not power vented. It runs 2-3' horizontal then 16' vertical to a roof penetration. No evidence of water leaking on the 14" pipe. Only at the furnaces and not all of them. Some are worse than other. The 1 shown is the farthest from the 14 and it is the worst.
     
  5. Chuck

    Chuck SSP

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    Underfired furnaces. Get the flue temp up over 300 and it will stop even with an oversized flue.

    I fixed a boiler chimney that was literally raining by removing the liner and firing it at full input rating. Dry chimney after that. Before you hit me for removing the liner it was very slightly undersized. And the larger existing liner was still in perfect shape. It was way oversized for the boiler so conventional wisdom said it shouldn't work. But they went from water running across the floor when the boiler ran to a completely dry chimney, no more moisture.
     
  6. Chuck

    Chuck SSP

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    Low return air temp can make the problem worse. Is there a lot of outside air or are they setting the space temp too low?
     
  7. Chuck

    Chuck SSP

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    What were your combustion readings?
     
    Zman likes this.
  8. Rather B Riding

    Rather B Riding Behind bars

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    608
    They do have 10 out side air piped to the returns that come off and ERV roof top unit. No heat or cool on the unit just heat recovery and desiccant wheel. I dampered those back most are 90% closed now. I did that day one of this account due to the problems they were having.
    I haven't checked combustion. Everything checked normal on fall start up. Gas pressures were good.
     
  9. mike1020

    mike1020 entitled millennial

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    on the roof of target
    It was running good
     
    Chuck and Jon like this.
  10. tuna

    tuna New Member

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    Is it all single wall pipe? If it is and it's going through cold unconditioned space, that would make water in the flue.

    You say just some are showing water. Are the wet ones the way water would trickle if it was condensing up above.
     
    Anita sannich likes this.
  11. Zman

    Zman Hanging by a Thread

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    1,017
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    The "I know a Guy" State
    I can't see that water heater Drafting properly on its own during the warmer months ,when no space Heating calls! I would add all BTUs,pipe sizes and chimney Height,then consult the National Fuel Gas Code Book,for proper Vent requirements.
     
    Rather B Riding likes this.
  12. Chuck

    Chuck SSP

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    And even if the sizing is correct and it still drips then what?
     
  13. Chuck

    Chuck SSP

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    This isn't aimed at anyone in particular, but I find it interesting that guys will pull out there volt meter instantly when a machine doesn't start but can't be convinced to use a combustion meter when there is a combustion issue. They will make multiple trips, swap parts, swap venting, and otherwise spend hundreds of dollars in time and materials and never use the tool that (with the proper training) would tell them exactly what was wrong, first time. Mind boggling.
     
  14. Jon

    Jon Team Canada

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    Canada eh!
    :D
     
    Chuck and Jay 41 like this.
  15. Chuck

    Chuck SSP

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    Nice edit :lachen:
     
  16. mike1020

    mike1020 entitled millennial

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    Seal the joints with foil tape and red silicone.
     
  17. mike1020

    mike1020 entitled millennial

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    Chuck it's burning good.

    Next thing you know, you will be telling me I need to buy a micron gauge.
     
    GTT and Chuck like this.
  18. Zman

    Zman Hanging by a Thread

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    Towels,lots if towels!:D
     
  19. Zman

    Zman Hanging by a Thread

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    At least you rule out one thing without replacing parts, even if all checks correct.Thats one reason I'd check Vent sizing.
     
  20. jamesyarbrough

    jamesyarbrough Amateur Gynecologist

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    Easy fix. Run a separate flue for every unit.
    :D