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  1. #1
    Join Date
    Dec 2006
    Location
    RI
    Posts
    29

    Returns in the outside walls, supplies in the interior walls. Is this OK?

    My daughter bought a single level ranch house with full basement, in New England. The furnace and all ductwork is all in the basement. Furnace was replaced and an a coil added some years ago. The ductwork is the original from when the house was built in the 1950s. The return air registers are placed in the outside walls down at the floor level and the supply registers are located in the interior walls, also at floor level. The house is being pretty much gutted and being renovated. My question: is this setup OK or should the returns draw from the interior walls with the supplies discharging at the outside walls? It seems to me to be backwards and should I consider trying to redo the supply and returns so that the supplies are along the outer perimeter and the returns at the inside walls.

  2. #2
    Join Date
    May 2008
    Location
    Central Fla.
    Posts
    311
    Let me just say this,thats how they used to do it back then. It's not how it's done now.It can be changed but won't be cheap.

  3. #3
    Join Date
    Nov 2006
    Location
    Athens, Ohio
    Posts
    1,902
    What he said.
    It works but the room temperatures are not as even as the modern design. The old design was created before furnaces had blowers to push the air. The supply ducts had to be as direct as possible for the thermal current to rise through the ducts.
    Because the exterior walls are the ones exposed to the outdoor temperatures, they tend to be the coolest places. When heated air (in the winter) is introduced into the rooms on or near the exterior walls it warms the surface which is the coolest and the air travels to the returns.
    As TwincamDave has said, a complete refit will be more costly than just keeping the old system.
    The primary consideration should be whether or not the old duct system will be properly sized for the new equipment. That will have to be determined by having a pro check out the system.

  4. #4
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    One reason to place supplies or with in boiler systems, radiiators, on the perimeter is to "wash" the windows with warm air to reduce feeling of cool drafts frmo cold air current off the cold glass surface. With modern windows this is less of an issue. The 2nd reason is that you want the least ductwork resistance/length in your returns. So making them closer to the centrally located system is beneficial. Additonally, wall cavities up until maybe the late 80's were the most common way of providing returns.

    On the flip side, if the ductwork is in an attic or uncoditioned space (not in this case) then reducing the lenght of the supplies means less heat loss wicne that's where hte air is warmest. Further, "washing" a wall with warm air, further increases heat loss in a space. That's another reason radiant floor heat can provide savings. Both increasing air movement and air temperature across a heat transfer surface (window or outer wall) will increase heat losses.

  5. #5
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,102
    I've got the same setup as the original poster in my house.

    Gets a little warm toward the center of the house, vs the outside of the house, but it doesn't both me enough to want to change it, especially since I'm comfortable between 65*-76*.

    If i was gutting my house though, I would change it though.

    Get those returns out of the (most likely block) exterior walls, frame the wall, and spray foam the crap out of it.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  6. #6
    Join Date
    Jan 2008
    Posts
    2,062
    Before I tore out all my duct work, I had the same set-up. The difference is COMFORT. Much more even temps.
    It's worth it if you're gutting the home.
    Is there new equipment in the equation? If so, the other major factor in comfort is proper sizing.
    99% of everything I see is over sized. It costs more to operate, and reduces comfort.
    "Hey Lama, hey, how about a little something, you know, for the effort." And he says, "there won't be any money, but when you die, on your deathbed, you will receive total consciousness." So I got that goin' for me, which is nice. - Carl Spackler

  7. #7
    Join Date
    Nov 2004
    Location
    SW FL
    Posts
    6,326

    Question

    What is a common center-exterior wall Temperature Difference in a living room with supply at the center?
    x ... ... X
    Designer Dan
    It's Not Rocket Science, But It is SCIENCE with "Some Art". ___ ___ K EEP I T S IMPLE & S INCERE

    Define the Building Envelope and Perform a Detailed Load Calc: It's ALL About Windows and Make-up Air Requirements. Know Your Equipment Capabilities

  8. #8
    Join Date
    Sep 2010
    Location
    Dubuque, IA
    Posts
    114
    hvacvegas, What type of heating system do you have?

    My parents have this same issue, but the basement is finished. I a, curious to see what the best option is to replace there furnace.
    Seatonheating "Well, when you are the salesman/layout guy/installer/owner, you kind of have to watch out for yourself."

    Words to live by my friends.

  9. #9
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,337
    I lived in a house in cold Minniesota built that way. Had the original 1937 lowboy when I moved in. No comfort issues. Some supplies high wall, some low wall, all returns under the windows. Sure can't see spending any money on changing things.

  10. #10
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    5,102
    Quote Originally Posted by Hindermanhvac View Post
    hvacvegas, What type of heating system do you have?

    My parents have this same issue, but the basement is finished. I a, curious to see what the best option is to replace there furnace.
    I have a 8 year old nordyne 90% gas, with a PSC motor.

    If they have a finished basement, leave it alone.
    One thing I did think about doing with it though, if it actually bothered me:

    Remove all returns. Spray foam openings. Drywall return space.
    Take all interior supplies (except bathroom and kitchen), and turn them into returns. I have to add a high wall though.
    Cut new supplies into floors.

    I get a tight (reletive to todays standard) return system because my (existing) supplies are ducted up the walls.
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

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