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  1. #1
    Join Date
    Jun 2008
    Posts
    34

    Rigid ducts versus Flexi ducts. Max Airflow?

    If I want to add some ducts, will they be Flexi ducts or do they still make Rigid ducts? My old ones are rigid?


    I have one duct that connects to three supply vents. The front foyer, the dining room and the laundry room. Air is being split three ways using one duct.

    The dining room has the thermostat and one return/one supply.

    I need MORE airflow into the dining room so that the thermostat drops easier without me having to point floor fans at the thermostat just to lower it or without the system running endlessly without shutting itself off. I want to run one dedicated independent duct from the dining room supply to the plenum.

    The return is near the ground and I feel the cool air is being sucked out of the room before it can reach the height of the thermostat which is 5 feet off the ground versus the return which is 6 inches of the ground.

    Let the laundry room and foyer vents run off one shared duct. 50/50.

    Dining room one duct, to increase airflow?

    Do HVAC people still install rigid ducts or only flexi ducts?

    Differences between rigid and flexi?

  2. #2
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    Either would work depending on the situation as long as they are sized properly.
    Its a good Life!

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Where are the suopply ducts,attic?

    Is the stat on an outside wall?

    Is the stat sealed from the wall cavity so no air is moving thru the wall and stat??

    Flex and ridgid will perform the sanme,if sized and installed correctly.the flex will be larger then ridgid ,as it's more restrictive,but being larger the results are the same.

    Flex is easier to installed and seal air tight,plus it comes with the proper insulation installed.

  4. #4
    Join Date
    Jun 2008
    Posts
    34
    Quote Originally Posted by dash View Post
    Where are the supply ducts,attic?

    Is the stat on an outside wall?

    Is the stat sealed from the wall cavity so no air is moving thru the wall and stat??
    1) Crawl Space.

    2) Stat is on an inside wall.

    3) I don't know? I ran some wires through the sheetrock and connected the Stat myself.

    Can you explain the correct procedure? I am clueless.

    Thx.

  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Air can flow up or down the wall for various reason,so the wire should be sealed to the drywall behind the stat.

    Sounds like you moved it ,it should be close to the main return to evenly sense the average temp..

    Even a garage wall,is bad as the wall will be warmer then the average temp in the home.


    Assuming floor supply grilles ,they need to discharge the air well above the stat.,for the best air mixing.

  6. #6
    Join Date
    Jun 2008
    Posts
    34
    Quote Originally Posted by dash View Post

    Sounds like you moved it, it should be close to the main return to evenly sense the average temp..
    No, I used the same original location. Swapped an analog for a digital. Stat is on an inside wall, the adjacent wall has the return. I think that return is sucking all the cool air out cause it is six inches off the ground.

    Assuming floor supply grilles, they need to discharge the air well above the stat., for the best air mixing.
    Nope. Supply grill is across the room on an exterior wall. Supply grill is 6 inches off the ground.

    How can the supply grill be any higher on a 1st floor, of a two floor house?

  7. #7
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    The return can definately move air in the wall.


    The height on the supply is not th issue,but it needs to discharge the air high enough in the room to "mix" it well,so the stat can sense the avaerage temp., and your head doesn't sweat when standing.lol!

  8. #8
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    metal if it's in a crawl or else you'll have infestation.



    insulate the duct too.
    FILL OUT YOUR PROFILE!!

  9. #9
    Join Date
    Jun 2008
    Posts
    34
    Rat infestation?

  10. #10
    Join Date
    Feb 2004
    Location
    chicago suburbs
    Posts
    4,422
    mice..rats.. anything that likes to stay warm and can chew through the flex.....adult children.
    FILL OUT YOUR PROFILE!!

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