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Help with proper sealing of ceiling cassette in attic

Bryce N.Bryce N. Posts: 7Member
Hello! I've recently had a 3 ton Hyper Heat Mitsubishi Heat Pump and 3 Ceiling Cassettes installed. 15,000 and (2) 9000BTU units. My main question is how to seal them properly in the attic. I want to keep the cold air from getting into the conditioned space which means I must seal the air handler from the attic as well correct?

The installer just put some rigid foam over the top which means all the cold air will just come right through. I feel quite ignorant on this topic and would really appreciate some help!

Sincere thanks,
Bryce

Comments

  • RobGRobG Posts: 1,850Member
    Every installation in a retrofit application is different. Can you post some photos?
  • IronmanIronman Posts: 5,232Member
    The unit's already sealed by the way it's designed and manufactured; you don't need to re-engineer it. The Japanese engineers are a lot smarter than you're giving them credit for.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • RobGRobG Posts: 1,850Member
    Ironman said:

    The unit's already sealed by the way it's designed and manufactured; you don't need to re-engineer it. The Japanese engineers are a lot smarter than you're giving them credit for.

    It sounded like he was talking about sealing around the exterior of the units to prevent heat and cooling from migrating from the attic? (granted, If that's the case it sounds they were not installed correctly). Hence the need for pics.
  • Bryce N.Bryce N. Posts: 7Member
    The units have a rigid foam box setting over top. However, there is no seal and in many spots, complete exposure to the attic. I can look right into my attic from the conditioned space (through the ceiling cassettes). Thank you for your help!!
  • GWGW Posts: 3,445Member
    Yes I'm not following this, where is the attic insulation? Is this a new construction?
    Are you saying the units plastic ceiling trim doesn't hide the hole cut? Where can you see through? These units should be air tight. Those boxes look quite flimsy.

    Gary
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    www.wilsonph.com
    [email protected]
  • Bryce N.Bryce N. Posts: 7Member
    Hi Gary,
    It is a remodel to the studs so not quite new construction but darn near:)

    I haven't had the insulation blown in yet as I want to make sure the air handler units are installed and sealed properly.

    The blue foam boxes are very flimsy and are not sealed. I realize the air handler itself is sealed but wouldn't I want to protect the unit from the cold/hot attic?



    Thanks!
    Bryce
  • Bryce N.Bryce N. Posts: 7Member
    RobG said:

    Ironman said:

    The unit's already sealed by the way it's designed and manufactured; you don't need to re-engineer it. The Japanese engineers are a lot smarter than you're giving them credit for.

    It sounded like he was talking about sealing around the exterior of the units to prevent heat and cooling from migrating from the attic? (granted, If that's the case it sounds they were not installed correctly). Hence the need for pics.
    Yes, RobG, that's exactly right. I'm trying to learn the best way to
    seal around the exterior of the units to prevent heat and cooling from migrating from the attic...as you perfectly stated:)

    What's the best way to do this?

    Again, thank you so much!
    Bryce
  • RobGRobG Posts: 1,850Member
    Can you post pics from below so we can see what you are working with?
  • IronmanIronman Posts: 5,232Member
    The unit is factory insulated and sealed to meet the federal energy code and certified by an approved testing agency to do so.
    If your seeing day light form below, then it's either not installed correctly or your insulation contractor needs to insulate properly. There is no need or practical benefit to attempting to build a box around it because of a perceived need to do so.
    Bob Boan


    You can choose to do what you want, but you cannot choose the consequences.
  • RobGRobG Posts: 1,850Member
    Is the ceiling grill installed?
  • Bryce N.Bryce N. Posts: 7Member
    Hi Rob,

    I haven't put the grills on yet as we are doing finish work. I understand that the unit itself is sealed, which is great news! I still have four gaps around each unit to deal with. I'll seal them from the attic and take pictures again. Thanks!
  • RobGRobG Posts: 1,850Member
    Do the grills cover up the gap? If so you can probably use some non-expandable spray foam and then just install the grills to cover the foam up. That will prevent the blown insulation from falling through.
  • Bryce N.Bryce N. Posts: 7Member
    Yes sir, they will cover the gap :) I'm going to crawl in the attic tomorrow and fix it up so I'll take some pics from the top (before & after) It may help someone in the future! Thanks for sharing your knowledge on here. I certainly appreciate it!
  • Bryce N.Bryce N. Posts: 7Member
    Here are the Mitsubishi ceiling cassette (air handlers) from the attic view. I didn't want to have blow in insulation falling through if I take the grill off for cleaning. Also, my understanding is, you want a good seal between your attic space and living space below. So cracks will be foamed before insulation is blown in.
    Any other input is very welcome! Thanks for the advice, guys!
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