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  1. #1
    Join Date
    Jun 2014
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    2

    Default hvac vent under bathroom vanity?

    In my old (1981) bathroom vanity, that I just removed, the air came up from the floor into the enclosed space under the vanity, then out a vent in the toe kick (no duct), it worked great.

    But my problem is different now. The vanity I bought has short legs -- no toe kick, no enclosed space underneath. The clearance from the floor to the bottom of the vanity is just 2 1/2". The HVAC duct (6") comes up from the crawl space through the floor, 4" in from the wall.

    I could install a floor vent under the vanity, and air would, more or less, find it's way to the room. But mostly, wouldn't I be making the vanity itself nice and warm/cool? I'm not very concerned about the air hurting the solid wood vanity (like from expansion/contraction, and I donít see how a vent underneath would be much different for the vanity than air going into enclosed space under a vanity) -- my concern is how inefficient it would be for heating and cooling the room.

    But I don't know what else to do (short of moving ductwork in the crawl space to a location not under the vanity; it's a tiny bathroom and a horribly cramped crawl space, I'm really not up for that) -- any suggestions?

    Thanks very much! ... Rick

  2. #2
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    1,375

    Default Re: hvac vent under bathroom vanity?

    How is this: Install a regular register grille for the size duct you have, and to it add one of these deflectors:
    http://www.deflecto.com/advp/product...Vents-p154.htm
    Remove not the ancient landmark, which your fathers have set.

  3. #3
    Join Date
    Jun 2014
    Posts
    2

    Default Re: hvac vent under bathroom vanity?

    Quote Originally Posted by Sombreuil_mongrel View Post
    How is this: Install a regular register grille for the size duct you have, and to it add one of these deflectors:
    http://www.deflecto.com/advp/product...Vents-p154.htm
    thank you! The deflectors would direct the air, and be an improvement, but better yet, a similar idea someone sent me solves it, I do believe, on Amazon, "Extend A Vent - Vent Deflector | Air Register Extender" which channels the air all the way out from under the vanity. I could probably fabricate a nice, simple one myself from spare wood , or buy this plastic one for $21, but I think it'll work:

    http://www.amazon.com/Extend-Vent-De...dp/B005AZ5KM8/

    funny how often solutions seem so obvious, once you're told!

  4. #4
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,884

    Default Re: hvac vent under bathroom vanity?

    If you do nothing, I don't think there will be any efficiency loss. Any heat absorbed by the vanity (during heating season) will eventually be radiated back into the room. During cooling season, the cold air will absorb heat from the vanity and cool it off. Then the vanity will absorb heat from the air, cooling it off.

    What you may notice is that the air in the room doesn't heat or cool as quickly after you adjust the thermostat. But once the desired temperature is reached, you won't know the difference.
    The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.

  5. #5
    Join Date
    Jul 2015
    Posts
    1

    Default Re: hvac vent under bathroom vanity?

    Quote Originally Posted by Fencepost View Post
    If you do nothing, I don't think there will be any efficiency loss. Any heat absorbed by the vanity (during heating season) will eventually be radiated back into the room. During cooling season, the cold air will absorb heat from the vanity and cool it off. Then the vanity will absorb heat from the air, cooling it off.

    What you may notice is that the air in the room doesn't heat or cool as quickly after you adjust the thermostat. But once the desired temperature is reached, you won't know the difference.
    Hello!

    Currently, I am in the same situation. I want to install a vanity with top in my second floor bath. However, I just saw that the HVAC would be blocked, since it's directly beneath the sink.

    As much as I am seriously tempted to just install it, I am bit concerned, based on an HVAC pro's advice.

    He mentioned the following:
    • Furniture should not block intake/flow vents
    • If furniture is place in front of said vents, push it away from the wall by 6 inches
    • Confirm that the vents are open in each room, esp. if that room is a problem (not hot/cold enough)


    The HVAC person also mentioned that your blower motor wears much faster when meeting resistance to the air flow.

    I'm not sure what I'll do, but please feel free to add anything that could help solve, or mitigate, air flow resistance. It is also important to get heat here, since it is a bathroom.

    Thanks!

  6. #6
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    2,002

    Default Re: hvac vent under bathroom vanity?

    It seems to me a few solutions were mentioned in the post:
    Put a grill in the toe kick
    Move the duct and grill
    Air deflector
    Duct extension
    Or use a vanity/sink that doesn't block the vent or allows for one of the above.

  7. #7
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    7,762

    Default Re: hvac vent under bathroom vanity?

    What ed said.

    Remember what your tech said: you make it harder on your unit, it will quit prematurely.

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