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cbrc5eric 06-08-2010 01:15 PM

Moving HVAC ducts/registers & reverse flow ?'s
I'm in the process of remodeling my dining/living room/foyer area. Long story short I have a small 1950's rancher with basement. I tore out 2 non-bearing walls, one was the foyer wall and the other seperated the dining room from the living room. The foyer wall had 2 HVAC vents which is now right infront of the front door :lol: I want to cap off one and relocate the other vent to the closet wall. The HVAC is original, it was not a retro-fit.

I can access the underside from the basement and the area directly below where I'm doing the remodel is in an unfinished utility area. The existing duct runs through a joist bay. I planned to just move the duct over 2 joist bays so I can have the vent either exit the floor or to use the closet wall (so it's not in the middle of the floor!). BUT in doing research I read that joist bays should not be used for supply air?? I've never heard of this before as many old houses have air ducts retro fitted wherever they will fit.

Second question- the house has reverse flow (supply ducts in the middle of the house, returns on the exterior wall). When I redo my basement, I plan on reversing the flow. I may even run new ducting on the outside wall of the house since the ducts hang very low in the middle of the already-low basement ceiling. Is it as simple as just reversing the ducts to reverse the flow?
I'll try to post pics later as it would be easier to show than explain in words.

But for now, my basic questions are:
1) Any truth in NOT using joist bays for supply ducts?
2) When I plan to redo my basement, I plan to "reverse" the reversed air flow, so the supplys are now the returns and the returns are now the supplies. Anything wrong with just using the existing ducting but reversing their flow?

beenthere 06-08-2010 02:06 PM

You might want to reconsider capping off that one supply. It might be better to relocate it also. On the hotter days you may need it.

A supply duct can run through/inside a joist bay.

A joist bay itself can't not be used as a supply duct.

If the returns in in the outside walls. Then you don't want to reverse air flow. As that will make your outside walls colder yet in the winter, and hotter in the summer. Outside walls should be washed with conditioned air. If the duct is in the wall, it can't do that.

cbrc5eric 06-09-2010 01:05 AM

Thanks for the reply- I might not described it well so Here are some pics of what I'm working with.

Here is the room (blurry cell phone cam) it started with

I tore down the walls- you can now see the HVAC ducting still sticking out of the floor. These are both supply ducts. I plan to move at least one of them to the closet wall that the wood scrap pile is laying on.

Shot looking in from the front door:

This is one of the existing return ducts (pardon the dust and the sheetrock sheets). It too is metal- BUT it's a return duct, NOT a supply duct, yet it is right underneath the window. Odd part is, in my kitchen there is a supply duct right under the window under the outside wall. I'd like to set it up so this register you see can be (hopefully) changed to supply. Yes, I realize I'll have to insulate it etc because it's in an outside wall.

Now- onto the basement.
Here is the underside of those 2 ducts seen in the previous pictures. I want to just move at least the one duct over 2 joist bays and then access that closet.

Here is the top of the furnace etc. Essentially the rearview of the above picture.

Here is the "finished" part of the basement that's outdated and past it's useful life :lol: . Pardon the PA system but I throw dance parties down there :lol: This is shot from the center of the room facing outwards. You can see how there is a very low section from the existing HVAC ducting right above my head. I am hoping to move this ducting towards the far wall- so the low section is on the wall- NOT in the middle of the room :willy:

beenthere 06-09-2010 05:05 AM

My set up is very similar to yours. With the exception being that my returns on/at the outside walls. Are floor returns.

if you do convert the system over to supplies on the outside walls. Make them floor supplies. So the air rises up and washes the walls. If you leave it as sidewall supplies. You won't be happy with how quickly you feel cold after the heat shuts off. Or how quickly you feel warm or hot when the A/C shuts off if you have central A/C.

Your duct work ran inside the joist bays like that are fine. No code violations, or safety issues with it.

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