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  1. #1

    Info Search: Cold air from vents, drafts, insulation

    Howdy all, here's my first post -- I'm looking for some information regarding an apartment situation.

    The Situation
    We live in a fairly new apartment complex in central Virginia. The unit we live in is a good-sized two-bedroom apartment with an open floor plan, a loft and vaulted ceilings, 1,479 sq. ft. The apartment is nice, but our first winter here (last winter) I found some drafts. This winter I noticed that when the heater isn't blowing, we would get cold air flowing out of some of the vents -- it feels just like air conditioning. Eventually this cools the apartment to the point that the heater kicks in and the place warms back up to thermostat levels. The cold air only comes out of the first floor vents, not the two vents in the loft.

    Some Details
    The structure is built on a hill, and is nearing 8 years old, and as it settles some cracks around windows and doors have developed. Management here is great. The day after we told them, maintenance came out, found gaps between the sheet rock and vents, and sealed them with foil tape. There are some other drafty spots that we sealed up, including around a malfunctioning Dimplex fireplace built into the corner (we never used the fireplace). Maintenance ordered a new motor for the Dimplex, and will seal up behind there when the motor gets here.

    The HVAC Follow-Up
    The day after maintenance, management sent out an HVAC pro. The furnace is in great shape, but it's clear the insulation is lacking in some spots near the living room vent. The heat that makes it out of the two loft vents and the bedroom vents is great, but the living room vent is never as warm. He and maintenance both separately raised the possibility of gaps in the air ducts.

    (Also, the return vent for the furnace is on the second floor -- which is just dumb in an open floor plan with a vaulted ceiling because the cold air is downstairs, not in the loft. They all recognize this; the company that installed the unit is from Florida and out of business. There's a ceiling fan to help circulate the warm air down/cold air up.)

    However, if there are gaps in the ductwork, the only way to get to them is by tearing up the ceiling. Not good, and it probably won't happen. But the HVAC pro and maintenance also suggested (again separately) that it might be a pressure difference; we don't use one of the rooms in winter, so we shut it up, shut the doors and vents, and we shut the two vents in the loft because the heat rises.

    The pressure thing has me wondering:

    The Questions
    After taping the gaps between the sheet rock and the vents, on a warmer day (upper 30's), I went around the place and checked for that cold air rush. For the first time since I noticed it, I didn't notice it. As it got colder that night, the cold air started flowing in again. We've set up oil radiators near the colder spots, and now I'm just curious -- could the cold air rush be from a gap in the ductwork, or something else?

    If there is a pressure problem because of closing vents/doors, could that end up causing the cool air flows through the first floor vents? Should we keep all the vents open -- and even the doors, or will that make much of a difference in the temp of the living room w/vaulted ceiling? When maintenance fixes the Dimplex, I'm sure sealing up gaps behind there will help, but should I look into having them blow some extra insulation back there as well?

    And if the cold air is the result of a gap in the ductwork, are there any measures one could take without having to tear up the ceiling?

    So it's:
    • Cold air sometimes rushing in through vents;
    • Uneven heating, with the living room vent never getting as warm as the others;
    • Poor insulation near the living room vent

    Thanks in advance for any advice. Beyond the caulking and weatherizing, I'm not talking DIY stuff here; I've already talked with the HVAC pro and maintenance, and we're looking into this. I'm just trying to get as much info as I can now so I can give them the best run-down when they come back, and we can have a warm apartment again without depending on space heaters.

  2. #2
    Join Date
    Jul 2007
    Are the vents under the windows? Are the windows old? Single glass, and do you have curtains on the windows?
    Always here

  3. #3
    Quote Originally Posted by energy star View Post
    Are the vents under the windows? Are the windows old? Single glass, and do you have curtains on the windows?

    The windows aren't all that old -- they're as new as the building, about 8 years, double-paned, and we have them 3M'd, curtained and shaded. There are some places in the frames where drafts could get through, but they're sealed up. But that doesn't mean they aren't letting cold air into the space between the walls.

    The one problematic vent isn't under the window -- all the vents are on the ceiling. But it is on the bottom part of the incline of the vaulted ceiling; the ceiling angles down from the loft at a 45 degree angle, which comes to an end and flattens out about 2 feet before the large living room windows (one frame with three double-hung windows).

    I attached a crude sketch-up that hopefully shows what I mean.

  4. #4
    Join Date
    Aug 2003
    Fort Worth, TX
    Is there an attic above the sloped ceiling of your living area?

    Is the loft open to the living area below? Does it also have vents in the ceiling, with an attic above it?

    Here's an experiment you can try. Open your front door just a crack. Try to do this when it is not windy outside. With the door open just a crack, see if you feel any breeze of cold air seeping into the crack from outdoors. Use your hand or your face to feel for this could also hold up a thin section of facial tissue to the door to see if it waves at you (pointing toward you). If you feel air blowing into your apartment, you have air escaping your apartment up high. This is called "stack effect", and is a considerable contributor to temperature differences between top and bottom floors in multilevel dwellings.

    One more you have any access hatches to the attic in the apartment (if there is an attic)? If so, do they (or not) have pulldown stairs?
    Last edited by Shophound; 01-04-2010 at 05:35 PM. Reason: substitute "apartment" for "house" and misc. editing
    Building Physics Rule #1: Hot flows to cold.

    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure

    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

  5. #5
    Quote Originally Posted by shophound View Post
    Is there an attic above the sloped ceiling of your living area?

    Is the loft open to the living area below? Does it also have vents in the ceiling, with an attic above it?
    There is an attic above the sloped area, and yeah, the loft is open to the living area below. The attic is above the vents in the ceiling of the loft, and they don't flush out cold air.

    Quote Originally Posted by shophound View Post
    Here's an experiment you can try... stack effect...
    I tried this earlier tonight, and did get some air coming in through the crack. I'm not certain how windy it really is right now; we live in the foothills of the Blue Ridge, and get some swirling winds as it is. But I also crawled up into the shelf where the TV sits, and found plenty more gaps. I caulked those up, and hung a heavy drape in front of the patio door off the living room. Those things have definitely made a difference. I'm redoing some window weatherization tonight.

    Quote Originally Posted by shophound View Post
    One more you have any access hatches to the attic in the apartment (if there is an attic)? If so, do they (or not) have pulldown stairs?
    The only access to the attic is out on the landing -- there's no access from within the apartment. I believe there are pull-down steps, but I haven't really checked. I suppose I could, but I think the hatch is locked.

    Man, you guys are thorough. I'm glad I posted the question. My wife was impressed as well.

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