Forum Discussion

BFL13's avatar
BFL13
Explorer II
Aug 05, 2020

8531 Furnace Duct Adapter Install Questions

https://www.amazon.com/Hydro-Flame-Corp-31474-Adapter/dp/B00CLSWS6I

I have an 8531 furnace with 4" knockouts for the ducts. The duct adapter is listed as 1474 in the manual, but get this on Amazon which seems to be the right part. I want to add a duct.

1. How do you get it in/on and to stay there after you knock out the knockout?

2. Do regular hardware stores sell these instead of using the Atwood part?

Thanks

EDIT--found this way down in the link above--not clear how it goes in the hole in the first place. " a 1/4 turn"
  • Old-Biscuit's avatar
    Old-Biscuit
    Explorer III
    Aug 05, 2020
    If you look closer there is a 'split' in flange that goes between furnace frame so after you remove knockout you slip it in and twist

    Duct goes ON the stub and is held inplace via clamp
  • subcamper's avatar
    subcamper
    Explorer II
    Aug 05, 2020
    I have added lots of these to my home HVAC system.

    You can buy them at Home Depot, Lowes, etc. Just find one that fits the hole/duct size.

    Usually they have a bunch of fingers that you reach through the hole and bend over against the inside of the plenum to hold it in place.

    Steve
  • BFL13's avatar
    BFL13
    Explorer II
    Aug 05, 2020
    subcamper wrote:
    I have added lots of these to my home HVAC system.

    You can buy them at Home Depot, Lowes, etc. Just find one that fits the hole/duct size.

    Usually they have a bunch of fingers that you reach through the hole and bend over against the inside of the plenum to hold it in place.

    Steve


    Great! Thanks to both replies. I understand it now.

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