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plenum

  1. HVAC
    Hoping someone can help. Current furnace is sitting on top of 17.5 in box plenum. The furnace is old and undersized. The a/c coil is newer and is 21 inch. Looking to purchase 21 in furnace. Newer furnace is shorter by about 6 in. Can I use the existing 17.5 in box stand and build a transition...
  2. HVAC
    I am looking to install a Spacepak system and am concerned about my tight space, behind the kneewalls in the attic. Its best if I install the unit with the service access facing out but this would require me to have two 90 degree elbows directly after the unit. I would have a total of 20 total...
  3. HVAC
    My next project is to install a powered humidifier and I have selected the Aprilaire 700. I have an upflow gas furnace with A/C coil above it, then an insulated plenum box above the coil which has the main trunk duct work attached to rear of the plenum box. The plenum box has insulation on the...
  4. HVAC
    Hi everyone, first time poster here. We are selling our home and the buyers inspector is recommending we seek professional help for two very obvious holes in our plenum that have been there since the house was build in 2008. I've always assumed that these holes were extra drainage or line...
  5. HVAC
    Hey all, I am in the process of doing a remodel and, after opening up a wall I want to remove, I see ductwork running through it. I want to eliminate this supply line as it seems to only feed one register in a small bathroom that we keep closed. I also need to relocate some returns on this...
  6. HVAC
    So I got some Knauf Duct Board at a very good price. However, once I got it home it seems very...fibrous. I run my hand calmly over the fiberglass portion and it feels like i'm scraping off very small particles. Is this normal? It has the intent of being used as a return plenum so air flow...
  7. HVAC
    Can flex duct be used in place of a normal return plenum? I've read it can so long as it is not the only return in the house but not sure how good the source was. 8" is probably the biggest I can use but the plenum takes up 2 joist cavities, so run 2 flex ducts? Thank you.
  8. Building & Construction
    So I removed the Panning for the returns and I found this going on. Is that hole there so the wall can breathe? Can I close it off? It connects to the return for the room upstairs and that is an outside wall.
  9. HVAC
    Soundproofing Air Return Plenum. I have 2 air return plenums in my basement and they echo and vibrate something aweful. What can i do to sound proof them or at least stop the echo/vibration. I'll be decoupling the ceiling so that'll help but still. Also, they're nailed flush to the joists...
  10. HVAC
    Sorry I don't know how to rotate these attachments. Is it just me or should this plenum be plumb and vertical, and yes.... it is also out of level by 3/8".:eek: I envisioned a tapered transition to a vertical 8" to a 90 degree turn at bottom. The sheet metal work was completed after I was...
  11. HVAC
    I am replacing my 41" tall, low boy furnace shortly with a Carrier Infinity 80BTU. The Return air duct on ceiling is 10" x 20" fed from the underside by a 12 x 20" X 90 degree turn which offsets sideways from the cold plenum. See attached .This 12 x 20 x 90 degree offset measures a total of 18.5...
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