DIY Home Improvement, Remodeling & Repair Forum

DIY Home Improvement, Remodeling & Repair Forum (
-   HVAC (
-   -   Moving a cold air return? (

WestBentley 02-28-2007 10:17 AM

Moving a cold air return?
Currently, the cold air return for our system is right next to the edge of our counter where the kitchen meets the dining room. It's really awkward and I can just see us dropping small items down the shaft by accident. So I want to move it to the other side of the dining room, just about 10 feet further where it'll be next to a wall and baseboard heater and not near where we intend to put any furniture.

Aaron isn't sure we can do it, and isn't sure he has the skills required to pull it off. I was hoping to get some information:

#1. Does cold air return hose only come in 25' lengths maximum? Aaron believes including the bend to go around an edge needed already leaves it 25' away.

#2. Does anyone have experience with putting in new subfloor and removing some? From what I can gather, it looks like we'd just cut the appropriate hole in the subfloor for the cold air return as long as the joists aren't in the way. Then for the old hole, we'd put down plywood (nail? staple? to the joists) on the hole, or cut the hole bigger to nail it to the joists if they aren't exposed by the existing hole.

I just think the current placement is really awkard and if the floor were whole there, it'd be the perfect place to feed our dogs. The "new" placement is away from any area that we would regularly be handling small items, so dropping things in wouldn't be a concern so much.

glennjanie 02-28-2007 12:06 PM

Hello Folks:
Putting the return air next to a baseboard heater will affect the performance of that heater to some degree.
Personally, I would run the return in metal pipe rather than flex duct.
Yes, cut the new hole between joists if it is possible. Closing the old hole could be done by adding 2 X 4 blocking between the joists.

WestBentley 02-28-2007 12:45 PM

I'm not that worried about that heater's performance, as it's a baseboard heater on an interior (??) wall, kinda unneccessary. I also thought that rather than having a potential draft by our counter, having it by a heater would counter-act any cold air issues.

What size/diameter/type of pipe would you use? Same as the flex duct? What do you use to connect it to the floor joists?

Daryl 02-28-2007 06:04 PM

You will need to keep the size of the new cold air return the same as the one you are replacing. Most homes only have one -two cold air returns for a whole home. Bear in mind this what returns all of the air flowing through your heating vents / air conditioning vents back to your furnace. if you make the size smaller you could restrict the amount of air flow being returned causing you furnace to work improperly. How is the current one constructed and how is it attached to the furnace? you probably cannot change the attachment configuration at the furnace and will have to figure out how to connect the new piping to the old one somewhere before the furnace. If you have a cold air return in every room (usually at the top of the walls) (with air conditioning in later model homes) then you should be able to make the changeover a little easier since the pipe diameter will be smaller and probably connects into a trunk line somewhere.

WestBentley 03-01-2007 09:14 AM

We aren't changing any sizes, just using the old "box" type and new but same sized hose to connect it to a different spot. It's for the AC only, as AC was added later.

BTW, how big of an issue do you guys think the whole near-a-baseboard thing is? The place is plenty warm now, the cold air return isn't attached to anything, just a bare opening in the crawl space. I don't want to ruin the effectiveness of the heat, but as I was planning on putting a rug over it in winter no matter where it's located (so we don't have to step on metal grate), I'm not too worried.

glennjanie 03-01-2007 07:29 PM

Yes, I would use the same size as the flex duct. You're going to be amazed at how much more air can travel through a metal pipe than a flex duct.
The return near the heater is not a big deal at all. I finally realize you have a hot water heating system and a seperate A/C systme; one will not affect the other in any way.
Janie says I'm thick headed but once in a while things come through clearly.

WestBentley 03-02-2007 10:02 AM

Aaron is concerned that metal pipe will be much harder to work with and much more expensive... do you have any thoughts/input? He's most likely the one to do it, so difficulty matters to him. We are newbies at this stuff and if I help (I may not be much of a help!) it'd probably just be holding stuff or handing tools.

glennjanie 03-02-2007 10:36 AM

Oh! no the metal pipe is easier for me to use. It comes in lengths from 2' to 5' and you attach an end to the furnace, hang the loose end with nylon webbing or plastic strap. Screw the first joint to the furnace pipe. Slip another length on, hang the loose end and screw the attached end (use 3 or 4 screws in a joint).
The pipe can be hung in a saddle of web or plastic band or you can screw the plastic strap to the sides of the pipe and to a floor joist. I prefer to use the nylon web strapping because you can fold the end, fold one side over to the other side in a 45 degree angle then fold the other side back over that and use a 1/2" staple to hang it, do the same on the other end. It is much quicker to hang the pipe with a staple gun.
I don't think the metal pipe will cost any more, maybe even less.

All times are GMT -6. The time now is 05:17 AM.