Air conditioning duct problem

[rob_fla]

Originally Posted by piper guy

Wanted to thank Michelle. Stuck camer up into the returns for the forward air unit and it looks like partial duct collapse on the one side. I think my easiest way out is to add two more returns to each AC unit. Looking at it, it shouldn't be too hard a job as long as my hole cutting is accurate. ��

When I looked in my returns, I could see the bubble foil was getting sucked down to the duct and blocking the air flow back to the A/C return.
I cut a set of new returns in the ceiling right next to the supply ducts so I could move the wiring blocking the air flow and put some solid foam strips above the supply ducts to keep the foil from getting sucked down on top of the supply duct and blocking the air flow.
The added returns, unblocking the wiring and stuff and supporting the bubble foil on top made a big difference in the efficiency of our A/C units.
Also added supply ducts as we did not have enough according to the A/C manufacturer.
The A/C manufacturer recommended a minimum of 5 A/C supply registers per 15k A/C unit. Our Redwood has two 15k A/C units and only a total of 7 supply registers (3 on one duct line, and 4 on the other duct line) we now have a total of 12 supply registers, 6 on each supply duct line and 4 return registers on each A/C unit.
All these mods along with cutting down all the supply register collars has worked pretty well for us.

[5th_Time]

No matter how many return registers you install downstream, the volume of air flowing back to the AC is restricted by the expanding foam that invaded the inside of the ducts - especially just before the plenum under the roof unit. You can see this when you are sealing the foam separating the supply & return plenums.

On mine, roughly 30+% was blocked under each unit. I reduced this somewhat by sawing & removing what I could reach, but plenty more visible that I couldn’t.

Disregarding the manufacturer’s specs, I don’t see the benefit of adding additional supply registers to further divide the supply when the complaint is low volume/pressure - especially in the bedroom of the RL/RE models.

[Ford truck guy]

Originally Posted by rob_fla

When I looked in my returns, I could see the bubble foil was getting sucked down to the duct and blocking the air flow back to the A/C return.
I cut a set of new returns in the ceiling right next to the supply ducts so I could move the wiring blocking the air flow and put some solid foam strips above the supply ducts to keep the foil from getting sucked down on top of the supply duct and blocking the air flow.
The added returns, unblocking the wiring and stuff and supporting the bubble foil on top made a big difference in the efficiency of our A/C units.
Also added supply ducts as we did not have enough according to the A/C manufacturer.
The A/C manufacturer recommended a minimum of 5 A/C supply registers per 15k A/C unit. Our Redwood has two 15k A/C units and only a total of 7 supply registers (3 on one duct line, and 4 on the other duct line) we now have a total of 12 supply registers, 6 on each supply duct line and 4 return registers on each A/C unit.
All these mods along with cutting down all the supply register collars has worked pretty well for us.

Rob, How far away from the supply ducts did you place your new returns? And did you do that for BOTH of the AC's?

[Ford truck guy]

Forget that.. I did some digging and printed the pdf file you nicely made for all

Can you remember where you got the rectangle, white return registers? !

[5th_Time]

I had Tiara order them from Redwood factory parts. They match perfectly.

[5th_Time]

Rob, did you have to pull the ceiling panels to do this?