Straight plenums for ducting ground floor rooms

[I N]

My MVHR unit is planned to be in loft space. 

 

As rooms are decorated, when I am running ducting into ground floor areas, I would be:
- running it through bathroom wall partition (for kitchen/hall) 
- boxing it in behind bedroom wardrobes to reach living areas underneath

 

This means that the duct run from loft to the ground floor ceiling vent is a straight vertical run. 

All off the shelf plenums appear to be 90 degree bends designed for horizontal runs.  Are there any solutions for vertical runs like I describe above? 

 

Alternatively, I can add couple of 90deg elbows and connect elbow to plenum, thus straightening it out. That kind of seems inefficient though, 90deg elbow and 90 deg plenum so two bends for a straight run. 

 

My ceiling joists are 8 inches deep and I would be running 2x75mm ducts into each  ground ceiling vent - not a great deal of room to play with. 

Edited December 5, 2022 by I N

[Russell griffiths]

 

one of these. 

[I N]

10 hours ago, Russell griffiths said:

 

 

one of these. 

thats the one, where do I order them?

[Russell griffiths]

On 06/12/2022 at 19:36, I N said:

thats the one, where do I order them?

CVC in oxford.