Below is my ac unit and the return duct that connects to the blower. I currently slide my 1-inch filter under that pvc pipe that's inside the furnace. PVC is in the way and there is no L-shape latch in the back of the furnace for the filter to hold, its only only in the front. So the filter gets sucked towards the blower. I decided to install 5" media air box outside between the furnace and return duct in the picture where 1 arrow is pointing.

Problem is, the return duct that's marked as 2 in the picture is not coming down straight, it leans towards the right which is why they installed the green flex duct or whatever its called and I won't be able to install the 5" rack like this because there will be some space in between. I have move the return duct to the right by couple of inches, Can I simply remove the duct and align it then cut the top duct by few inches and cover the old space?

I will also move the condensate pump to the left of the furnace first.

Edit: Added more pictures

In pictures you can't really tell clearly but that long duct is not straight. It needs to be moved 1-2 inches to the right to make it straight.

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  • How well is the system circulating air? If I understand correctly, you are creating a minor bottleneck in the return.
    – JimmyJames
    Jul 18, 2018 at 21:08
  • I'm not sure what "cut the top duct by few inches and cover the old space" means.
    – isherwood
    Jul 18, 2018 at 21:09
  • i think that the OP may be talking about the plenum above the return duct
    – jsotola
    Jul 18, 2018 at 21:13
  • Jimmy currently air flow is not that great because of the bent filter situation, air is being pulled into the blower around the filter due to which I'm wondering if ac coils are freezing and reducing the air flow.
    – Sam
    Jul 18, 2018 at 21:41
  • isherwood, by top duct I mean, the dust you see in the picture, where its connected to the top. imagine this T but it's coming down \ like this at the moment. I need to move a few it from the top a few inches to make it straight |.
    – Sam
    Jul 18, 2018 at 21:45

1 Answer 1


Here is what I would do. First, move the condensate pump to the left side of the furnace to get it out of the way of the return duct. Make sure that you add enough pipe unions so the pipe could be removed for furnace service. You may even be able to use a flexible tubing instead of the rigid piping. I would then measure from the bottom of the return duct to the wall to see how far I could move the duct. I would draw a diagram of the duct I would need with an "S" offset to move the duct to the right as per the drawing. Disconnect the whole return drop from the horizontal piece to the furnace connection. Take the duct that you removed and your drawing to a sheet metal shop and have them fabricate the "S" offset or a completely new duct including a filter rack. Also have them add a canvas connector to the vertical run to make installation easier. You could then take the new duct to your home, install it, and you now have an easy filter change and a correct duct. If this out of your expertise, you could call an HVAC shop to do the work. Hope this helps

  • Thank you d.george! This helps. I would like to do it myself even though its out of my expertise. I like trying things and love learning and save money. I did call HVAC guys and I've been given quotes close to $1000 to do this job. I really don't want to spent $1000 to move a duct and installing a rack. I didn't know I could take it to sheet metal shop. I may do that now.
    – Sam
    Jul 19, 2018 at 17:50
  • You could visit a vo-tech in your area and ask the HVAC instructor if he has any student that could help. It would give the student some experience, give him a few bucks, and give you some needed help. They may even be able to fabricate the duct. The duct would be made in several pieces, the first drop, the "S" curve or offset, a canvas connector, the elbow, and the filter rack. You may even end up with a large enough filter rack piece that you could install a "hepa" type filter that would do a better job of filtering the air in case a family member has allergies.
    – d.george
    Jul 20, 2018 at 10:18

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