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Discussion Starter #1
I'm installing a furnace and a/c coil horizontally in a crawlspace. The furnace is at one end of the house and a trunk line runs to the other end. All of the heat ducts on the furnace end need to be snaked somehow to the plenum. This means that the duct leaves the floor joist cavity and runs perpendicular to the joists until it reaches the plenum. I can save myself 2 90's if I position the takeoff on the underside of the plenum as opposed to the usual top of the plenum. Which is better; having the takeoff on the bottom or having the takeoff on the top with two extra 90's to contend with?
 

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Use the bottom.

Sounds like furnace is installed that it only uses to joist to support it.
 

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Discussion Starter #3
yes, it hangs from the floor joists. There is a high water table (beside a lake) and if electricity were shut off there would be flooding. thanks for the response.
 

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I meant to say only uses 2 joist to support it.
 

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Discussion Starter #5
The joists are perpendicular to the furnace direction on 16" centers so the whole assembly will hang from 5 or 6 joists. The main beam runs between the supply and return trunks so there is lots of strength.
 
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