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  1. #1
    Join Date
    May 2012
    Posts
    5

    Booster fan for basement air return?

    I have a new high-efficiency furnace with two large air returns in the floor on the main level, another air return on the 2nd floor (and also opening to the cathedral ceiling space), and an 8" air return located at floor level in the basement. The heated part of the basement is separate from the furnace room. Supply for the basement is ceiling outlets. The furnace is mounted up about a foot and a half from the basement floor due to the shape of the basement. Thermostat is on the 1st floor.

    The problem is (surprise) the basement is cold, the air does not get warm enough. Actually there is a gradient and your head can be quite a bit warmer than your feet. Closing down the upstairs supplies helps somewhat but not enough. The basement supply seems to be adequate as it is comparable in amount to the upstairs supply and in addition you can feel warm air coming out. It seems to me that the air intakes on the first floor are drawing well but that the air intake in the basement is not drawing very much. There are no dampers in the air return system.

    The basement intake goes up about 6 feet vertically to reach the main return duct in the basement ceiling. Incidently the basement intake connects to the main return duct not far from where the first floor intakes are.

    It seems to me that the heavy cold air is sitting in the basement and not making it up the 6 feet to the main return duct. Consequently I'm wondering would help to put a booster fan on the basement air intake. This would help lift the cold air into the furnace (if the furnace is running) or to the upstairs where it would hit the thermostat (if the furnace is off).

    Being a total newbie, my question is: is this a totally wrongheaded idea? What other approach could help? My HVAC guy is busy with family right now and I'm trying to think through what approaches might help.

    Steve

  2. #2
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,829
    Trying to manipulate room stratification with return air is most often a losing proposition. I'd suggest you investigate having the basement supply air installed lower to the floor, such as a low wall outlet that can blow across the floor.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,288
    In this case I would say a return air inlet in the basement mounted close to the floor might help a bit, provided the return has no way to backdraft the furnace. Skippedover is correct in that supply air distribution more readily solves thermal gradiant problems in a room, but a combination of supply and return placement in some contexts is required to increase comfort.

    I would also look around the basement for air leaks from outside your house into the basement, as basements can be leaky areas due to utilities that must enter or leave the house at this location. Building leakage can lead to a lot of discomfort problems that the heating system gets blamed for.
    • 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.

  4. #4
    Join Date
    May 2012
    Posts
    5
    Thanks for the comments. Putting the supply closer to the floor is an interesting idea. I had thought the HVAC guy put them in the ceiling for a reason but I guess the reason might have been convenience. It's true though that one of the supplies can't really be put near the floor without building an ugly bulkhead, and the others would have to be pretty much ripped out and redone to get them inside of walls ... actually even for those it's a bit questionable whether it could be done since several of the walls are concrete block and these can interfere with the runs.

    As for leaks from outside ... I don't think it's much worse than upstairs, at least not in the finished half of the basement.

    From the browsing I've done it seems that this is a fairly common problem ... what is the most common solution? I don't want to put electric baseboards in as they cost big $$ around there for the electricity. Besides it seems unasthetic to put in a furnace and then have to supplement it with electric baseboards.

    Is there any downside to putting in a booster fan (aside from wasting $$ trying it)? I don't have a gas water heater at present and I believe the furnace is taking air from outside, and plus it's in another room so I don't think that backdraft would be too likely.

    All the best
    Steve

  5. #5
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,829
    Booster fans don't work. They can't create enough static pressure to overcome what's already inherent in the duct. So they just spin along, using electricity and accomplishing nothing. You can't fool physics. They are the laws of nature and no matter how hard you try, physics wins.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  6. #6
    Join Date
    May 2012
    Posts
    5
    ?? I don't get it. Why wouldn't the fan be able to move the air? All it has to do is push it up 6 feet (in an 8" round duct) so that it will fall into the furnace intake. Well, I guess I could put the fan at the top of the duct so that it pulls the air instead of pushing it.

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