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  1. #1

    Air loss thru water drains

    Hi,

    I just replaced two 23 year old Rheem systems with Carrier Infinitys. I was very impressed with the install but the water drain from the coils got me thinking. The original system had closed PVC lines but the new system has an inline switch and an open pipe at the top. The switch turns off the unit if water backs up and the open pipe was explained as an overflow rather than have water back up in the coil unit. Sounded logical at the time, but now I see that the open pipes (and I guess the old closed pipes that vented to outside) pump out conditioned air. On the downstairs unit, I guess that's okay because at least that conditioned air eventually finds its way into the living area but the upstairs unit is between the ceiling and roof, so the vented conditioned air is wasted.

    Seems strange with all the emphasis on efficiency these days that there isn't a way to not pump conditioned air where it does no good. I'm not too concerned since I now realize the old systems were both pumping that air outside, so the new layout is at least some improvement in that regard.

    Comments?

  2. #2
    Join Date
    Jun 2006
    Location
    New Jersey
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    4,340
    I having trouble understanding. Can ya take a picture?

    The only open vent should be after a trap, if needed. And with a trap there should be no conditioned air venting out.

  3. #3
    Quote Originally Posted by ascj View Post
    I having trouble understanding. Can ya take a picture?

    The only open vent should be after a trap, if needed. And with a trap there should be no conditioned air venting out.
    Sorry. I should have posted a picture before.


  4. #4
    Join Date
    Dec 2003
    Posts
    2,425
    Put a piece of duct tape over it, or a short piece of pipe/cap with no glue.

  5. #5
    Join Date
    Dec 2004
    Location
    Grand Rapids, MI
    Posts
    622
    I agree, cap it. Also, is that the electrical power coming in on a grey wire ? Is there a service switch ? luck dan

  6. #6
    Join Date
    Dec 2008
    Location
    Buffalo NY
    Posts
    3,140

    Cool Where is the trap?

    If they would have installed a trap you would not have these issues.
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  7. #7
    Quote Originally Posted by bigtime View Post
    Put a piece of duct tape over it, or a short piece of pipe/cap with no glue.
    The only reason I didn't already is that then the pressure would then push the conditioned air out the other end of the pipe which is outside the house. At least now, the downstairs vent goes into the living area. Upstairs the open pipe is in the attic which is only slightly better than outdoors.

    I'm mostly just curious if venting conditioned air to the outdoors is the norm these days. The old units used the same drain pipes just without the shutoff switch or open vent so it never occurred to me that the drain pipes were pressurized with conditioned air until I felt it coming out these vents.

  8. #8
    Join Date
    Dec 2003
    Posts
    2,425
    Put a piece of tape over it. It was a small detail that was overlooked. Soon, someone will say it needs a trap, because the instructions say one is needed. The amount of air blowing out through 15 feet +/- of 3/4" pipe is not enough to worry about.

  9. #9
    Quote Originally Posted by danielworkerbee View Post
    I agree, cap it. Also, is that the electrical power coming in on a grey wire ? Is there a service switch ? luck dan
    The grey wire (three element ribbon cable) is the power to the unit. Why do you ask? That cord plugs into a wall outlet you can see thru the opening between the drain downpipe, the overflow shutoff and the gas flex hose.

    What's a service switch? Would that be if the power cord wasn't just a plug in? I'm guessing there are also probably manual and/or automatic switches when some panels are opened.

    Quote Originally Posted by qwerty hvac View Post
    If they would have installed a trap you would not have these issues.
    What's a trap? You mean like under a sink?

    I think I'm understanding. The trap would have some standing water during hot months that kept the cold air from getting thru.

    It just seemed strange to pay for 21 SEER and 17.3 SEER units yet pump conditioned air outside.

  10. #10
    Join Date
    Nov 2008
    Location
    DFW,TX
    Posts
    2,189
    well a furnace like that doesnt require a trap however some city codes do so check that ,also im not seing an issue with the plug ,thats a standard 110v furnace/appliance whip and it doesnt require a disconnect /breaker like a 240v system does,at least not that i know of..

    i also agree the little bit of air loss is normal and so low it really isnt effecting your system,

    no more then leaving a filter in a few days/weeks longer after you know it needs changing or not rinsing off your outdoor coils more ,or not having regular maintenance performed ,or not having gutter or splash guard over outdoor unit where roof water dumps right on top of unit all year long..note these are all bigger issues you should be concerned about.

  11. #11
    Join Date
    Nov 2008
    Location
    DFW,TX
    Posts
    2,189
    I did just notice this,how is that t switch supposed to work if the t is opened and water is allowed to pour out the top above it?i dnt think thats correct as i would have put switch in overflow port at evap pan or after the first 90 off the main line.

    anyway maybe its the angle but that switch doesnt look like it will do anything like that,looks like a mistake to me..

  12. #12
    Join Date
    Nov 2000
    Location
    Upstate, SC
    Posts
    2,919
    I would have trapped the drain to the outside and put the switch, or one similiar to it, in the overflow hole of the coil which doesn't appear to be being used in the picture. Has anyone actually measured the amount of cfm going down a 3/4" pvc drain?

  13. #13
    Join Date
    Dec 2008
    Location
    Buffalo NY
    Posts
    3,140

    Cool Plug in furnace?

    I may have read it wrong but do you mean your furnace is pluged into a wall outlet and not hard wired on its own circuit? I know this is illegal in NY I think it is illegal in the national code. The air leak is the least of your problems if this is the case.
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