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11 comments
Anonymous Poster #1

HVAC Air Return Location Question

01/24/2012 6:57 PM

OK...I own a two story home with centeral air and gas fired furnace. We have a wood burning fireplace in a family room with vaulted ceiling. The ceiling in this room is pitched two stories tall on one side one story tall on the other.

When we do have fires in the fireplace it is for asthetics not really for heat...however I'm considering trying to capture the heat rising to our valuted ceiling by adding a couple small returns and tying them into the main return which is on the opposite side of this two story tall wall. The idea would be to pull out the hot air at the top of the ceiling and recirculate it through the house using the furnace fan.

I have no HVAC experience but I do know the temperature diffence between the floor and this cieling is significant especially when we are using the fireplace...meaning a lot of heat is being wasted.

Does anyone see a problems with this?

I do not want ceiling fans...

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#1

Re: HVAC Air Return location Q:

01/24/2012 7:49 PM

Good for heating, not so good for cooling..Before I assumed anything I would check the temperature difference during typical usage....How would you run the duct is the other problem...Have you considered an HRV system..

http://www.hometips.com/buying-guides/heat-recovery-ventilator-hrv.html

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#2

Re: HVAC Air Return Location Question

01/24/2012 9:17 PM

Consider using the gap between the studs in an interior wall to house a metal duct. You will have to expose the horizontal 'plate' 2X4s and remove that wood. As long as you don't harm the strength of the house, you're ok.

Put a grille at the top, and connect the duct to your furnace fan. Put a control damper in it to close when the fireplace is off.

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mike k
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Anonymous Poster #1
#3
In reply to #2

Re: HVAC Air Return Location Question

01/24/2012 10:36 PM

Mike K wrote: "Put a grille at the top, and connect the duct to your furnace fan. Put a control damper in it to close when the fireplace is off."

The main return trunk is directly behind and at the top of the tall wall (which is attic space) so adding a couple of returns between the studs will be relatively easy.

I guess now the question is whether I should have dampers to close these off when not in use or in the summer...though I'm not sure if I need to? The main return is at the top of our stair case...so I'm not sure that there would be much difference...

Why would I need to ever close these off?

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Anonymous Poster #1
#10
In reply to #2

Re: HVAC Air Return Location Question

01/27/2012 10:37 AM

This addition of the returns would be of benefit regardless of whether we are using the fireplace...since this vaulted cieling acts like a heat trap.

Yes there is no arguing the inefficiency of the wood burning fireplace...but you can't beat it for ambiance!

Thanks for all the input! Since this will be a relatively simple/quick project I think I will give it a try.

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#4

Re: HVAC Air Return Location Question

01/25/2012 8:29 AM

mike k nailed it right on the head. (GA)

I have the same type architecture in my home and the upper return is a great idea.

I used rafter space for a return between the exposed rafters up in the vault. I also lined the space with sheet metal before I closed the duct in.

YES, do go with dampers!

I installed a butterfly valve (damper) at the intersection of the main return and ceiling return at the furnace.

This has come in very handy during the AC season to pull all that hot air down from the ceiling as I close the valve off completely to the lower lever return ducts.

During the winter, I adjust the butterfly to 1/3 and 2/3 between the ceiling and floor returns.

I did find through experimentation that if during the winter, I close off the lower level completely, the floors get cold this being why I adjust to 1/3 and 2/3.

You idea of running the furnace fan is right on! I also set the furnace fan to run constantly while my fire place is heating to circulate the heat from the ceiling area throughout the house.

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#5

Re: HVAC Air Return Location Question

01/25/2012 6:19 PM

This low cost idea might be beneficial.

Buy a couple 14"x14" return air filter grills.

Mount them back to back high on the wall near the HVAC return air and a put a piece of foam, plywood, etc. in the upstairs one when running A/C.

With standard 16" center stud spacing you will have about 14 1/2 inches between them and will not need to cut a stud. Consider the location carefully and cut like there's a wire in there.

Air flow from convection and the slight vacuum from the HVAC return air will cost nothing and require no wiring. Turn the HVAC blower on at the thermostat if you want to, but normal cycling of the furnace may be enough.

I think you are wise to consider relocating this heat. Good luck with it!

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#6

Re: HVAC Air Return Location Question

01/26/2012 7:47 AM

Find a ceiling fan that you can live with, the results are well worth it and some are very attractive. Instead of all this duct work for the upper hot air consider adding some short ducts to supply combustion air to the fireplace from outside to reduce the heat loss from the operating fire place. It worked for me.

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#7
In reply to #6

Re: HVAC Air Return Location Question

01/26/2012 12:58 PM

Great answer. Unfortunatly I can only give a "Good Answer".

Simple and you run the fan as desired for comfort, summer or winter. And the Dedicated OA reduces cold drafts in other areas when fire place is operating.

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#8

Re: HVAC Air Return Location Question

01/26/2012 1:42 PM

I have a better ideal. Seal off the chimney and put in 36" LCD in front of the fireplace with some scented candles. The loss of heat through the chimney is greater than anything you could get out of it. That's even with outside air coming in for the fire. I bet all the other rooms in the house get cold.

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#9
In reply to #8

Re: HVAC Air Return Location Question

01/26/2012 10:28 PM

An even simpler option!

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#11
In reply to #9

Re: HVAC Air Return Location Question

01/28/2012 2:09 PM

Much thanks

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