[Gizzat]

Hi all!

Given that HVAC unit return is smaller than media filter
Could you advice on which type of transition to use?
1. Right or angled (and if so - what angle?) - does it matter for return side?
2. would it matter if there is another return duct coming to the side of plenum

adding a small drawing

 

[BaldLoonie]

B due to the transition leaving the filter. I don't see a problem with a 2nd return into the side of the plenum.

 

[kdean1]

Use a transition. The goal is to reduce or eliminate turbulence as much as possible. The air should flow evenly through the filter for best performance.

 

[Gizzat]

Use a transition.

which version?

 

[kdean1]

which version?

Whichever one reduces turbulence the most. Air does not like to change shape or direction. Even the connection of the round duct to the box would benefit from a transition. Turns in flexible ducts should be done with a metal elbow instead of curving the duct.

 

[BaldLoonie]

1 and 3 you have air slamming against the metal where the truck line hooks up. 2 is the only one with a transition and would have the least restriction of the air.