# Location of cold air returns



## Richo (Dec 6, 2007)

Well, I am into the HVAC stage of the basement finishing project. The area is about 700 square feet.

With the existing duct work in the basement for the main floor, I was limited on where I could put the heating ducts for the basement.

For accessibility reasons, I am also extremely limited on where I can put the cold air returns. There are really only 2 feasible locations.

This is quick drawing of the layout of the room and ductwork. The red circles show the locations of the heating vents and the blue rectangles indicate the only places I can run the cold air returns.










I can work in ceiling cold air returns in other locations but to locate them at the floor, these are the only 2 places that work.

I guess I'm just wondering if the location of these returns is going to be sufficient?

Thanks for your input.


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## ben's plumbing (Oct 6, 2011)

if this is the only place you can put them its better to have cold returns than none at all ....they will work ok


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## gregzoll (Dec 25, 2006)

My basement is a little larger than yours. I have mine on the opposite side of the basement from the water heater. That way, I do not draft the water heater. In your picture, in what relation is the water heater & furnace, and are they direct vent, with makeup air from outside, or are they getting their make up from inside the home?

Figure in the space, you do not want the cold air return next to the furnace, but away from it, so I would suggest putting it on the far wall. Can you put up a better floor plan, and some pictures of the space please.


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## Doc Holliday (Mar 12, 2011)

ben's plumbing said:


> if this is the only place you can put them its better to have cold returns than none at all ....they will work ok


 
If you have no choice. If the ceiling is an option it'll work better.


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## Richo (Dec 6, 2007)

Here is a diagram with the furnace and water heater drawn in:









Here is a photo of the area with the cold air returns. The stud bay outlined in blue is the one in question since it's so close to the furnace and water heater. The water heater does not appear to draw air in from outside, only vent to the outside. The furnace does have 2 PVC pipes going outside.








What is the detriment to having the cold air return close to the furnace or water heater if it is fully enclosed? How can it draw in unwanted air if the only opening is on the finished side of the wall?

This photo is from the back side of the wall which will be unfinished.








The blue arrows point to where I was planning on cold air returns. The left one can tie into a joist bay that is an upstairs cold air return and the right one would tie into the trunk line directly above the stud bay.

If you look at the first photo you will see that the main structural beam is a barrier between the main area and the cold air trunk line. I could do ceiling cold air returns and tie into the trunk line from above but I heard that whenever the heat is blowing down from the ceiling the returns should be at floor level. Is this not true?

Hopefully this all makes sense the way I explained it. Thanks for your help.


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## gregzoll (Dec 25, 2006)

Is your water heater just power vented, or is it drawing fresh air for make up from outside, same for the furnace? For the cold air return, you will have to go into the joist bay to place one in the room facing, and for the room you are in, that you took the second picture, if it is open to the furnace, you could just get away with the vent in the lower portion of the trunk, if you are not enclosing the furnace.

The only concern is going back to the water heater, that you want to have the cold air return, so it is not going to interfere with the water heater flame, if it is a standing pilot. That is my only concern.


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## Richo (Dec 6, 2007)

> Is your water heater just power vented, or is it drawing fresh air for make up from outside, same for the furnace?


I don't know much about these things but the water heater is power vented to the outside, only one PVC pipe though, so I'm guessing it can't be drawing any air in from outside.

On the other hand, the furnace does appear to have an intake PVC pipe. There are 2 PVC pipes attached to the furnace going outside.

The furnace and water heater are going to be in the unfinished section. There will be no cold air returns facing that area.



> For the cold air return, you will have to go into the joist bay to place one in the room facing


Could you please elaborate a bit on this? I'm not sure I understand what you mean.

Thanks


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## gregzoll (Dec 25, 2006)

If your water heater is receiving its make up air from inside, you are going to have to figure out how to get it make up air, due to you are finishing the basement space. As for the statement of running the cold air return into the joist bay, it means exactly that. Right now, you have more to do, than just slapping some gypsum on the walls and ceiling, what you are talking about with the mechanical s, should have been planned, before you laid a piece of lumber on the deck, and started to pound nails.

When you plan something to be built, you make a drawing of how you want the walls, one for mechanics's; one for plumbing; one for electrical; one for a/v, data, telco. Right now with the walls up and wanting to figure out where to put the cold air returns and duct work for heated/conditioned air is not where I personally would want to be, since I would have figured this out as stated before I even got to putting up the walls.


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## Richo (Dec 6, 2007)

Well, the original plan was to go with electric baseboard heat and then someone suggested feeding off the furnace instead because it's more efficient. At that point it was already planned out and framed.

So then is my issue with the basement finishing more about starving the water heater of makeup air than it is about the location of the cold air returns for the finished side? If this is the case, the unfinished space that the water heater is located in is still about 500 square feet all by itself so is that really going to be a problem with lack of air?

Regarding the water heater, it's electronic ignition.


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## Richo (Dec 6, 2007)

After looking over the area a little more, I found an alternate location (C) for a cold air return that will also work:









If the B location is too close to the furnace and water heater, will C work any better?

The trunk line for the cold air return is only 22 feet long so anywhere I tie in, other than location A is going to be somewhat in the vicinity of the furnace.

As mentioned in an edit to my previous post, the furnace and water heater are both electronic ignition, so I don't have to worry about a standing pilot.

Thanks.


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