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  1. #1
    Join Date
    Jun 2008

    No Return Air-Flow?


    First post...Great site!

    As many others have experienced, I have a hot upstairs in a 2-story house. New construction circa 2002. Out of the 4 bedrooms, the only one that is cool has suction from the return register located at the top of the wall in the room. This room is located in the center of the house directly above the furnace and uses the wall cavity between the studs as the return duct. Plenty of suction through the register in this room. The other 3 rooms that are significantly warmer use 8 or 9 inch insulated flex duct that is connected to a large wall cavity next to the furnace. The flex duct runs from that connection through the attic and down to the rooms through a ceiling register. There is probably 100 feet total of flex duct including a junction box where the single duct branches out to 3. There is not only no suction in the ceiling registers, but there is minimal at the start of the flex duct at the wall cavity. I know the cavity is not blocked because I tossed some rope through the opening and it came out at the furnace connection.

    I just got off the phone with the company that installed the furnace and the service tech stated that there shouldn't be any air-flow through the return ducts and they are there to release the pressure in the room. His exact words were " you should be able to hold a candle next to the return registers and not have it move much." I found this statement a bit odd as other threads I have read state that the return registers should be able to hold a piece of paper when the fan is on.

    I was going to have the company come out at my expense ( out of warranty) but the explanation from the service tech seemed off. I am no expert, but shouldn't the return ducts all pull air back to the furnace?

    I have a 3 Ton Carrier System. House is around 2000 square feet. I even went so far as to disconnect a branch of the return ducting for the downstairs and blocked it off as to create more air-flow for the upstairs. Went back in the attic where the flex-duct started and still nothing.

    Thanks in advance for your responses.
    Last edited by chevys10; 06-09-2008 at 06:39 PM.

  2. #2
    Join Date
    Feb 2004
    That answer is bull. All returns need airflow through them, no air in means no air out. If only one is pulling air that means you probably have too little air flow through the air handler, reducing performance and efficiency.

    Call another company.

  3. #3
    Join Date
    Aug 2002
    Office and warehouse in both Crystal River & New Port Richey ,FL
    The supply air needs a return path to the systems return air,or the supply will be reduced in that room.

    That said supply air needs to be the minimum required to cool/heat the room.

    Check this thread about returns.

  4. #4
    Join Date
    Mar 2008
    Grundy Co. IL
    Sounds to me like he's trying to B.S. you into thinking his company did things right, please get a second opinion (since you're paying anyway), before yor unit is damaged.

  5. #5
    Join Date
    Dec 2007
    Cedar Grove, Wi-Sheboygan
    Seems to me that these other 3 duct runs are not connected to the return at the furnace is there's no air being sucked into these reurns??? Are there any dampers on any of these runs not that there should be on the return side but on the supply side you should have dampers, maybe those are closed. Just seems odd to have only 1 return register that is functioning properly and 3 that are not, Maybe you should investigate this alittle more, you maybe able to find the problem yourself it may just be a matter of reconnecting the return runs, or there may be kinks in the flex duct !!! If not get someone who is quailified and knows what there doing or at least knows what there talking about. When you call someone ask them a few simply question on your system and judge by his answers will save you and the other company time if they give you a answer like this guy is giving you. Good luck !!!

  6. #6
    Join Date
    Jun 2008
    Thanks for the replies. I am in the process of getting another company to come out and look at the situation. There is actually an HVAC guy in my neighborhood that has the exact same model house as I have so I am hoping to run into him and hire him to take a look for me.

    There is actually no airflow at the start of the flex ducts. There is a large triangular wall cavity that is being used as a duct immediately above the air handler that connectsto the flex ducts.

    My belief is that the cavity is too large, at least 4' by 3' and 12' high and the air is being drawn from leaks in the cavity rather than the through the flex duct. I have considered trying to run a flex duct through that cavity, but that would require cutting holes in walls and ceilings. I really need to have a professional come out and look at it.

    Thanks again...

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