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  1. #1
    Join Date
    Apr 2016
    Location
    N. Va
    Posts
    13
    Post Likes

    Attic Supply Plenum replacement/Reconfig advice

    Hello,

    I have learned a lot here and appreciate everyone who contributes. I'm looking to have an AC Tech to come out and replace my Attic duct board supply plenum because of mold and the butchered installation that was done 2yrs ago. What led me to inspect the coil/supply plenum is the diff in temps from the left 12" Flex supply line (56F) to the master bed and bath from the right 10" Flex supply (59F) that supplies a bed room, Hall/Foyer and bath room which the rooms are always warmer.

    I found mold in the supply plenum and the transition they made is not insulated. I want to get an idea of what should be done so when they get up there I will know if they are in the ball park.

    Equipment:
    York P3HUA12N04801B 80% Natural Gas Furnace
    Inside coil ICP N Type 2.5 Ton TXV END4X30L17A1 Aprox 65ft of line set from condenser. Correctly offset to left as per manual
    Outside condenser Heil 2.5Ton HSA630GKA100 10 Degree Sub cooling
    14" main Flex return in hallway
    8" Flex return from Master Bed

    The unit has 4 Flex supply runs to cover 1500sq ft upstairs. 8", 9", 10" and 12". All Flex supply lines feed the triangle pie boxes then flex taps off to feed individual areas.

    I think the unit should have been horizontally installed from the beginning as you can see the supply is almost touching the roof.

    Should I insist on an insulated metal supply that extends to the left to the next supporting truss then reroute flex lines or duct board like current config?

    I think the mold may be due to the coil being so close to the supply lines. Thanks for any advice you can provide.
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  2. #2
    Join Date
    Sep 2014
    Location
    NW Arkansas
    Posts
    1,056
    Post Likes
    I didn't read any of the post, sorry. But what I can tell you is that you need to 1) you need to have a load calculation done (manual j).
    2) you need to have someone design your duct system for you (with manual d & t).

    I would require all metal ductwork (other than a small section for sound transmission) and only eternally insulated.

    I would also require 1 or 2 high performance air filter 4-5" thick.

    Mold does not grow on metal, plasit, or insulation. Mold will grow on dust. So first you have a dirty system (dead skin and hair) second your airflow is t correct providing mold an opportunity to grow on its food.

    Sent from my SAMSUNG-SM-G891A using Tapatalk

  3. #3
    Join Date
    Sep 2014
    Location
    NW Arkansas
    Posts
    1,056
    Post Likes
    Also, talk to someone about bringing the ductwork and furnace inside the home envelope and out of that attic.

    Sent from my SAMSUNG-SM-G891A using Tapatalk

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