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  1. #1
    Join Date
    Sep 2007
    Location
    Western NY
    Posts
    26

    Default Heating issue for one room

    I have a heating issue that Iíd appreciate some advice for. This is a long post so Iíll apologize in advance.

    My home is in Western New York. It itís a Cape Cod and was built in 1950 and has forced air heating. The furnace is a 90+ condensing furnace. To help you visualize the issue the furnace is located in the SE corner of the basement and the main trunk runs along the East perimeter of the basement.

    The kitchen is 12í x 14í and is heated by a 7Ē run that is approx 20í long before the register exit. This heat run is located above a drywall ceiling in a finished portion of my basement so thereís not much I can do about this run.

    The heating issue is with the eating area which is adjacent to the kitchen located in the SW corner of my home. This room is 8 x 13 and was constructed over an unheated crawl space that used to be a porch. I have no idea how well floor of this area is insulated. The walls in this area have 3 Ĺ in fiberglass insulation. The windows are Andersen thermopane and are at least 20 years old (thatís how long weíve been here and they were here when we moved in). They are in good condition with no apparent leaks.

    This eating area is heated by a 7Ē run that runs for ~20 feet (and contains 5 elbows) before it reaches a 7x7x6 tee which feeds one of two parallel 3 ľ x 10 ducts that run under the floor to registers on the outside (south) wall. After that tee, the run is reduced to 6Ē for another nine feet and feeds the other 3 ľ x 10 duct.

    The airflow from the 2 registers served by the 3 ľ x 10 ducts in the eating area is very low and the temperature of the air seems barely above room temp. Iíve sealed the joints of the duct that I can get at with foil tape in an effort to eliminate any leaks that might be contributing to the low flow, but it didnít make much difference.

    Iím thinking about increasing the size of the duct feeding these 2 runs to 8Ē if it will make a significant difference. If I do make that change, I will be able to eliminate 1 of the elbows but thatís the best I can do in that regard. I also thought about feeding only one of the two 3 ľ x10 ducts in an effort to take better advantage of the airflow that I do have but Iím not sure if thatís the best way to go.

    Iíve attached a couple of photos in an effort to better explain the situation. Photo 1 is where the first underfloor duct takes off and photo 2 is from the other side of photo 1 showing the duct as it continues and connects to the second underfloor duct.

    Thanks in advance for any advice and assistance.
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  2. #2
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Heating issue for one room

    I'll assume that you've already tried choking down the dampers to the other rooms in an attempt to get more flow to this duct run.....and it has been unsuccessful.

    And so.....I'll suggest you consider both insulating that run and adding a duct booster-fan.

    http://www.myhvacparts.com/Catalogue...20Boosters.htm

    Also....is there a cold air return in this room? If not, I'd be adding one.
    Last edited by goldhiller; 01-01-2009 at 01:21 PM.

  3. #3
    Join Date
    Aug 2008
    Location
    Fairfax, VA
    Posts
    76

    Arrow Re: Heating issue for one room

    We have a similar problem in one of our bedrooms upstair. We have 3 bedrooms and a bath, and all get very hot, while the one bedroom stays very cold. We have been looking into a second heating unit for the upstairs, but didn't know if that would be cost effective since all the other rooms are well heated. We have just been using a space heater to take the chill out then turning it off right before bed, and back on for a little while in the morning.

    Any thoughts? The one bedroom is above a den area that is open, but one other bedroom shares the same den area, but remains warm.

    Air flow seems to be the same for both.

    Thanks,
    NOVA Pros

  4. #4
    Join Date
    Sep 2007
    Location
    Western NY
    Posts
    26

    Default Re: Heating issue for one room

    Thanks ****hiller.

    Yes, I've already adjusted the dampers on the remaining heat runs to (attempt to) balance out the airflow.
    I've considered adding one of those booster fans but then I would have to wire the power to the fan contacts, etc. etc. so that the fan didn't run all the time.
    I guess the main question I was attempting to get an answer to is whether increasing the pipe size by one inch (from 7" to 8" would result in a significant enough increase in airflow to make it worthwhile.
    The cross sectional area would increase by ~ 15%. Does that amount to an increase of 15% in airflow or would it be greater (or less)?
    As far as adding a cold air return to that room it's not possible and given that it's so close to the kitchen I don't think that would be a good design anyway.

  5. #5
    Join Date
    Aug 2007
    Posts
    1,131

    Default Re: Heating issue for one room

    but then I would have to wire the power to the fan contacts, etc. etc. so that the fan didn't run all the time.

    Not at all. Go back to the linked page and look underneath the booster fans. There you will see the PS 1503 Pressure Switch which will control the booster via the air flow in the duct.


    The cross sectional area would increase by ~ 15%. Does that amount to an increase of 15% in airflow or would it be greater (or less)?

    I'm not sure. It *might* work out that way in the real world/in your particular situation......or it might not. Would depend upon where you tie in with the larger duct, the general duct layout, blower cfm output, etc........me thinks.

  6. #6
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: Heating issue for one room

    Quote Originally Posted by Dave239 View Post
    I have a heating issue that Iíd appreciate some advice for. This is a long post so Iíll apologize in advance.

    My home is in Western New York. It itís a Cape Cod and was built in 1950 and has forced air heating. The furnace is a 90+ condensing furnace. To help you visualize the issue the furnace is located in the SE corner of the basement and the main trunk runs along the East perimeter of the basement.

    The kitchen is 12í x 14í and is heated by a 7Ē run that is approx 20í long before the register exit. This heat run is located above a drywall ceiling in a finished portion of my basement so thereís not much I can do about this run.

    The heating issue is with the eating area which is adjacent to the kitchen located in the SW corner of my home. This room is 8 x 13 and was constructed over an unheated crawl space that used to be a porch. I have no idea how well floor of this area is insulated. The walls in this area have 3 Ĺ in fiberglass insulation. The windows are Andersen thermopane and are at least 20 years old (thatís how long weíve been here and they were here when we moved in). They are in good condition with no apparent leaks.

    This eating area is heated by a 7Ē run that runs for ~20 feet (and contains 5 elbows) before it reaches a 7x7x6 tee which feeds one of two parallel 3 ľ x 10 ducts that run under the floor to registers on the outside (south) wall. After that tee, the run is reduced to 6Ē for another nine feet and feeds the other 3 ľ x 10 duct.

    The airflow from the 2 registers served by the 3 ľ x 10 ducts in the eating area is very low and the temperature of the air seems barely above room temp. Iíve sealed the joints of the duct that I can get at with foil tape in an effort to eliminate any leaks that might be contributing to the low flow, but it didnít make much difference.

    Iím thinking about increasing the size of the duct feeding these 2 runs to 8Ē if it will make a significant difference. If I do make that change, I will be able to eliminate 1 of the elbows but thatís the best I can do in that regard. I also thought about feeding only one of the two 3 ľ x10 ducts in an effort to take better advantage of the airflow that I do have but Iím not sure if thatís the best way to go.

    Iíve attached a couple of photos in an effort to better explain the situation. Photo 1 is where the first underfloor duct takes off and photo 2 is from the other side of photo 1 showing the duct as it continues and connects to the second underfloor duct.

    Thanks in advance for any advice and assistance.
    Yikes .... I can see why your having issues with that set up.

    The first thing that comes to mind is I highly doubt that 7 inch supply is nearly enough for the CFM required for that space.
    If that branch that comes off the "T" is suppling 2 vents that likely means there is another "T". If so ..... I'll bet you are seeing less than 135 CFM being delivered out of those 2 vents.
    Then reducing down to a 6 inch for another vent some distance away .... you will end up with a low CFM delivery as well.
    Combined with all the elbows , distance , how well the ducting is sealed and insulated under the floor would result in very little warm air being delivered.

    In my opinion you need to have an HVAC contractor to properly calculate what's required for that space and design and install a proper duct supply ( trunk and branch ) and possible return ducting.
    They would also need to determine the velocity requirement of the furnace to provide the supply need throughout the entire heating system.

    2 cents worth.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  7. #7
    Join Date
    Jun 2007
    Posts
    1

    Default Re: Heating issue for one room

    I just moved into a new colonial (2 story) and had similar heating/cooling issues.

    To resolve this issue we had an Arzel zoning system installed. You can set different zones (with different thermostats) to control each one of these areas. It works very well.

    Click on the below link to review:


    http://www.arzelzoning.com/

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