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  1. #1
    Join Date
    Jan 2009
    Location
    Harrisburg, PA
    Posts
    32

    Water dripping from ceiling air vents on 2nd floor....

    I have a 2 story house, each floor with it's own zone/heatpump.

    I'm not running the heat upstairs, and I keep all the doors closed to the rooms upstairs.

    I have the thermostat set around 50 degress. There is an air handler in the attic, and I noticed around the air vents in two rooms, water was dripping out of the vents and the drywall was wet around the ceiling vents.

    I went up in the attic, which is probably 40 degress my guess, and removed the duct from the vent in the ceiling and there was water in the duct. Not a ton of water, but enought to drip out. How could this happen? It's winter here in PA and I have't been running the upstairs unit.... Thoughts?
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  2. #2
    Join Date
    May 2007
    Location
    Columbia, SC
    Posts
    58
    If I had to guess (which I do because I really don't know) I would say that warm air from your house is hitting cold air in the attic causing condensation. Again, I'm no expert, but I'd say that your duct work doesn't look like it's attached particularly well to your vent boxes... It'll be interesting to see what the experts say.

    Heath

  3. #3
    Join Date
    Sep 2009
    Posts
    382
    The attic will become very cold (attic 40F during the day when sun is up). It seems that you have a square diffuser box which may or may not be insulated internally. In any case, add more insulation to the exposed box in attic and foam-seal the gap between the box and ceiling dry wall so that the warmer 2nd floor room air won't leak into attic and condensate. This is still not going to be enough, because the room air can get into the diffuser box through the vent and condensate, unless you tape shut the entire vent.

    you will need to leave on the 2nd fl heat, which will dry out any condensate. Or, tape seal all vents on 2nd floor.

  4. #4
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    Best case scenario is it's like the boys say. A little better insualion and your off to the races. Worst case is that the handlers condensate line aint functioning correctly. Coils pan can be damaged or cracked. Line trap might not be right causing air to be drawn back into the system and the pan spilling. Just a thought.

  5. #5
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    insulation won't solve that. you are reaching dew point on the register face because you aren't running the system. happens all the time on homes with a/c in the attic and radiant heat.

    you either seal the registers (supply and return) or you run the system periodically to stay above dew point.
    Perhaps you should have read the instructions before calling.

  6. #6
    Join Date
    Jun 2006
    Location
    Michigan
    Posts
    962
    In an unused attic system, there will be air movement from the house into and through the ductwork even when it is off. When the air from the space hits the cooler temps in the attic it will condense inside the ductwork. You have to either stop the flow by sealing all the vents (supply and return) maybe large sheets of magnetic material on the grills or something.

    Or you could run the fan continuously or get a stat that will run the fan automatically at certain time intervals to keep the inside of the duct above the dewpoint.

  7. #7
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    JR
    interesting and well thought out reply. How dose the dew point thing work on the register faces please?

  8. #8
    Join Date
    Nov 2004
    Location
    NJ
    Posts
    1,203
    ^ conduction

    Ed J

  9. #9
    Join Date
    Feb 2009
    Location
    north of 49
    Posts
    233
    looks good to me!

  10. #10
    Join Date
    Jan 2009
    Location
    Harrisburg, PA
    Posts
    32
    Thanks for the responses guys. The reason that vent box in the pic is exposed is because I brushed off the insulation ontop of it.

    Now, could this also be happening because I had all the doors shut to the rooms on this 2nd floor? As I said, the hallway upstairs has a bacony that is open to the downstairs. This 2nd floor hallway is always warm, since the heat from the 1st floor system rises of course. What if I open up the doors to the rooms to get some of that warmer air in? Or if I'm reading correctly that could make it worse.

  11. #11
    Join Date
    Jun 2006
    Location
    Michigan
    Posts
    962
    The only solutions I know of are to either seal all the supply and return openings completely, or circulate air through them to keep the air temp in the ducts above the dewpoint.

  12. #12
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,327
    Pull the vent grill off your supplies where you see water. Seal the gap between the drywall and the sheetmetal vent box. Let the sealant you use (mastic or silicone caulk is okay) dry thoroughly before you put the grill back on. Do this to every vent that comes into your house from the attic. The vent grills may have a little foam strip on them, but they typically do NOT seal your house from the attic. Air from your house is escaping into the attic and crossing the dew point on the cold vent box and grill. The vent box can get cold even if it is buried under insulation because the ducting connected to it is also hooked to an air handler in a 40 degree attic, which can get pretty chilly hanging out up there by its lonesome.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  13. #13
    Join Date
    Jun 2006
    Location
    Michigan
    Posts
    962
    Quote Originally Posted by shophound View Post
    Pull the vent grill off your supplies where you see water. Seal the gap between the drywall and the sheetmetal vent box. Let the sealant you use (mastic or silicone caulk is okay) dry thoroughly before you put the grill back on. Do this to every vent that comes into your house from the attic. The vent grills may have a little foam strip on them, but they typically do NOT seal your house from the attic. Air from your house is escaping into the attic and crossing the dew point on the cold vent box and grill. The vent box can get cold even if it is buried under insulation because the ducting connected to it is also hooked to an air handler in a 40 degree attic, which can get pretty chilly hanging out up there by its lonesome.
    He has water IN his ductwork. If it was from leaks at the grill or boot, seems like the water would be on the outside of the duct.

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