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  1. #1
    Join Date
    Sep 2012
    Posts
    37

    How would you address this?

    I have two systems in my home that I'll be replacing in the next couple of weeks. These pictures are of the downstairs unit, located in a utility room off the garage. This furnace and evaporator coil are the originals installed in the mid-70's, and they've earned the right to retire.

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    Today, I pulled the front panels (scraps of that lovely mid-70's wood paneling) off the return-air box the furnace is sitting on so I could have a look inside. It was just as nasty as I thought it might be after 37 years. The return duct is a 14" round pipe in the adjacent crawl space that connects to a 20X20 filter grille about ten feet away. I see no caulking or other sealing agents. What I do see is mold and mildew general filth--and a return duct that's a little smaller than it ought to be for a 2 1/2 ton AC and 80,000 btu furnace that's somewhat blocked by the undersized hole they made in the wall.

    I've never seen an installation quite like this. Is this sort of return-air box common for that period? The plywood top is both sagging and de-laminating, and the whole deal looks like dumpster bait to me.

    If you were doing this job, how would you approach this? Keep the bones and replace the sides and top, scrap it and build a new one, or scrap it and just bring the return air duct through the wall and into the side of the furnace? The supply duct that goes into the crawl space could be raised by 6 or 8 inches to make more room for the return if necessary. The 3 sales guys who've bid on this so far didn't seem overly concerned, but then again they weren't the guys who'd have to do the install.

    Thoughts?

    Thanks!

    D.
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  2. #2
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,836
    I would scrap it and build a new return plenum out of sheet metal for the unit to sit on which I hope is what the installers will do. Surely they won't reuse that. Make sure, especially the return side, is completely sealed so it doesn't pull in fumes or co from your car or water heater and distribute it through the house.

  3. #3
    Join Date
    Jul 2007
    Location
    Delaware
    Posts
    3,824
    I would have the contractor tell you exactly what he is going to BEFORE he does it. You need line voltage work and if mine, I would remove ane clean/paint the room. Check back in later, you will get more suggestions.

    And yes, fabricate a whole new return

  4. #4
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
    Posts
    710
    I would agree to previous answersand also I would change the water heater as I think it is againest code to have it sitting on the floor of the garage.Once a contractor steps foot on the job he has "superior knowledge" and cannot leave without rectifying the problem. Especially if he is working on the new gas tie in for the new furnace.

  5. #5
    Join Date
    Aug 2012
    Posts
    2,645
    YIKES. Complete changeout.

  6. #6
    Join Date
    Sep 2012
    Posts
    37
    Quote Originally Posted by skibme View Post
    I would agree to previous answersand also I would change the water heater as I think it is againest code to have it sitting on the floor of the garage.Once a contractor steps foot on the job he has "superior knowledge" and cannot leave without rectifying the problem. Especially if he is working on the new gas tie in for the new furnace.
    It's not on the floor of the garage--it's in an adjacent room with a concrete floor 6" above the garage floor.

    D.

  7. #7
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    Quote Originally Posted by skibme View Post
    I would agree to previous answersand also I would change the water heater as I think it is againest code to have it sitting on the floor of the garage.Once a contractor steps foot on the job he has "superior knowledge" and cannot leave without rectifying the problem. Especially if he is working on the new gas tie in for the new furnace.

    Just to elaborate. This isn't some senseless PITA code. This type of water heater has an open flame and open combustion. Gasoline vapors when spilled, will hang low along the floor in an enclosed space. IF they reach the water heater burner or pilot, boom! followed by either the wall catching on fire, or worst breaking the gas line connection, so now you have a flame thrower and up goes the garage, car and your house. All because the water heater wasn't elevated off the ground and a little gaoline got spilled.

    They talk about adding sprinkler systems as a new residential requirement. Just addign them to garages would be a good start.... of course they have to be filled with glycol and tested annually and the water supply in most homes isn't large enough, so you'd probably need a storage tank.

  8. #8
    Join Date
    Sep 2012
    Posts
    37
    So in this case, would we be better to use a plenum under the new furnace, or just put the furnace
    on the floor and run the return into the side?

    D.

  9. #9
    Join Date
    Oct 2010
    Location
    Anderson, South Carolina, United States
    Posts
    6,836
    Plenum under unit IMO

  10. #10
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    New plenum under. Sheet metal plenum and seal it up. Have it and the connecting duct or round pipe sized correctly and also sealed up

  11. #11
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
    Posts
    710
    Where does the flue pipe run? Post a pic of the chimney.You might have another problem brewing.

  12. #12
    Join Date
    Sep 2012
    Posts
    37
    Quote Originally Posted by skibme View Post
    Where does the flue pipe run? Post a pic of the chimney.You might have another problem brewing.
    It enters a pipe chase that takes it all the way to the attic, then through the roof. Once it enters the wall, it's a straight shot to the roof. Wall is sheetrock.

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  13. #13
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
    Posts
    710
    If the flue went to the outisde of the garage then up the side that would be considered a "outside" flue.This type of flue requires a chimney liner be installed.but your ok if the flue pipe stays interior till the roof. Elevate your water heater up off the floor and change out the unit and ductwork.

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