# Another cold air return question



## Bandit03 (Mar 5, 2012)

Here is my dilema and I'm hoping someone can offer a few suggestions to help.
I have a downstairs bedroom that was originally a attached garage.  The previous owners converted it to a bedroom and built a new attached garage next to the room.  This room has 2 ceiling supply vents but no cold air return and the door seals the room pretty tight.  This room has been extremely cold in the winter and unbearable in the summer since I bought the house a few years back.  The house has a relatively new heater (gas) and my heating/cooling bills have been outrageously expensive.  So I climbed in the attic (access from the garage goes over the bedroom and kitchen ceiling).  I found that I have 2 6" supply lines to feed the bedroom vents.  One line was totally disconnected and laying on the insulation.  The other line was rigged up with duct tape and wasting major money.  One line goes direct to a vent in the front of the room.  The other line tee's off to a vent above the door but on the kitchen side and proceeds to the vent at the rear of the room.  I have read several responses to questions on cold air returns.  I do not have any idea of how much air the heater is designed to move.  The heater is actually placed into a closet accessible only from the outside of the house and intake and exhaust protrude over the doorway.  The fit of the heater into this closet restricts most access and would allow me to retro a 4" return back to the heater from the bedroom.  Would this assist in helping to warm the room when I have the door closed?  Would a 4" line be acceptable or should I try to increase the size to a 6 or 8" return?  The door is closed 99% of the time to keep the dogs out.  Any help or suggestions would be appreciated.


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## paul52446m (Mar 5, 2012)

Bandit03 said:


> Here is my dilema and I'm hoping someone can offer a few suggestions to help.
> I have a downstairs bedroom that was originally a attached garage.  The previous owners converted it to a bedroom and built a new attached garage next to the room.  This room has 2 ceiling supply vents but no cold air return and the door seals the room pretty tight.  This room has been extremely cold in the winter and unbearable in the summer since I bought the house a few years back.  The house has a relatively new heater (gas) and my heating/cooling bills have been outrageously expensive.  So I climbed in the attic (access from the garage goes over the bedroom and kitchen ceiling).  I found that I have 2 6" supply lines to feed the bedroom vents.  One line was totally disconnected and laying on the insulation.  The other line was rigged up with duct tape and wasting major money.  One line goes direct to a vent in the front of the room.  The other line tee's off to a vent above the door but on the kitchen side and proceeds to the vent at the rear of the room.  I have read several responses to questions on cold air returns.  I do not have any idea of how much air the heater is designed to move.  The heater is actually placed into a closet accessible only from the outside of the house and intake and exhaust protrude over the doorway.  The fit of the heater into this closet restricts most access and would allow me to retro a 4" return back to the heater from the bedroom.  Would this assist in helping to warm the room when I have the door closed?  Would a 4" line be acceptable or should I try to increase the size to a 6 or 8" return?  The door is closed 99% of the time to keep the dogs out.  Any help or suggestions would be appreciated.


I would need more info. To do a rough heat loss of this bed room 
 Whats the sq. footage of the room?
 Whats the heights of ceiling? 
 How much insulation in ceiling? 
 Sq footage of out side cold walls?
 Cement floor no insulation?
 Sq foot of windows?
 What kind of windows, single or double glass?
 What size is sq. foot of the rest of the home?
 How many hot air opening? 
 A 6" pipe split into two open is still the size of one opening. 
 A 4" pipe for return air is nothing, not worth running.
  I am sure you will need more hot air in this room.
 If you leave the door open so the air can get out of the room
 Do you know what size of you furnace and what the cfm of the blower.
 What is the make and model of the furnace. 
 Moving air is a home only works when the ducts are sized right, If you return air ducts are too small you can't move the air.  
 Put half doors in to keep the dogs out or if you have a wall from bed room to house put grills through the wall to let return air out.     Paul


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## Bandit03 (Mar 6, 2012)

Thanks for the response, Paul.  I will try to gather as much info as possible and get back here asap.
Joe


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## Bandit03 (Mar 6, 2012)

Hi Paul,
Here is as much info as I could gather.  SF of the room is 253 ft with 8 ft ceilings.  Ceiling insulation is approx. R16 with 4" of cellulose on top of the batt insulation.  SF of the outside cold walls is 165 sf.  Original cement floor and covered with plywood subfloor (not sure if insulated or not).  SF of 3 windows combined is 25 sf with Anderson double pane windows.  The rest of the home is approx 1,800 sf.  The bedroom has two heat vents that are ceiling mounted.  I do not know the size or cfm of the heater but will attempt to upload pictures.  The heater is a York GY9S080B12UP11G gas fired.  I do have a vent mounted over the door facing the kitchen side of the house and that is the one tee'd into one of the 6" supply lines to the bedroom that I could remove and cut a grill opening on the bedroom side but would that be an issue up high?  I do have room to cut grill openings approximately 6 inches above the floor height.  Also, the 2 6" supply lines are flex duct with booster fans in each to increase the air flow.  Would you recommend replacing the flex with hard duct due to increased friction of the flex?


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## paul52446m (Mar 7, 2012)

A 6" pipe can run 110 CFM of air through it if it has the right pressure behind it. You would need 3- 6" round pipes going to this room. You would need at least 80 sq." of return air grill going through the wall down close to the floor to let the air back 
 out of the room. You can check your furnace blower wires and tell me how many wires come from the blower motor to your electronic board and what colors are on what post. This will tell us what speed the blower is on. 
 Right now that is about as far as i can go with having all the furnace specks ans complete layout of the duct system, and
 sizing of the ducts.    How long are these 6" pipes?     Paul


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## mudmixer (Mar 7, 2012)

The easy way to look at it without details - You can't get warm air into an area unless you get the cool air out - it is called circulation.

Dick


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## Bandit03 (Mar 8, 2012)

HI Paul,
Thanks for the info!  There are 5 wires coming from the blower to the board.  Red is on a Park Tap, Yellow is also on a Park Tap, Black is on Low Cool Tap and Blue is on Heat.  A white wire goes to a neutral block on the upper right side of the board.  I'm attaching a picture of the board and taps.  Thanks again, you have been a wealth of information and patient as heck!
Joe


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## paul52446m (Mar 8, 2012)

Bandit03 said:


> HI Paul,
> Thanks for the info!  There are 5 wires coming from the blower to the board.  Red is on a Park Tap, Yellow is also on a Park Tap, Black is on Low Cool Tap and Blue is on Heat.  A white wire goes to a neutral block on the upper right side of the board.  I'm attaching a picture of the board and taps.  Thanks again, you have been a wealth of information and patient as heck!
> Joe



Take your doors off or electric cover off and find you wiring diagram.
Between the yellow and blue coming from the blower, i don't remember which one is med Lo and med Hi . you want the Med Hi on the heat post.
 With out seeing the rest of the system it would be hard for me to go any further.  Paul


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## paul52446m (Mar 8, 2012)

mudmixer said:


> The easy way to look at it without details - You can't get warm air into an area unless you get the cool air out - it is called circulation.
> 
> Dick



Your post is really helping this person out???    Paul


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## mudmixer (Mar 8, 2012)

You have to understand the principal before looking at the details.

I have 3 levels with open stairways and can maintain 2F maximum difference whether the temp is -20F or +100F irregardless of the hardware if you look at the circulation and do not try to use a bigger hammer or sophisticated energy source.

It seems the OP was concerned with getting the air out and was talking about air circulation, duct diameters and not really anything about the real supply equipment. Apparently, the OP got directed into the nuts and bolts and specific energy supplying equipment without much concern about the air system.

Dick


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## Bandit03 (Mar 9, 2012)

Hi Paul,
Thank you very much for taking the time and lending your knowledge to answer my questions.  I will be installing the vents at the lowest level on the wall that I can this weekend and will let you know how things proceed from there. 
_I've seen a few other posts from another member but have chosen to take the high road and abide by this site's rules of respectful behavior, as much as I would like to otherwise._  I took the time to read over the rules of this site and will abide by them and I hope that if I ever have the opportunity to assist another person, that I don't come across as condescending or otherwise.  I have not received any helpful information or guidance from anyone on this site with the exception of you and I am very grateful for you taking the time to try to assist a stranger.  Your information has been extremely helpful.  You have answered the specific questions that I was looking for and also gave me a little more knowledge of things under the hood.  I may not have all the schooling in the world, but I like to think that I'm bright enough to ask questions to issues that I don't know the answer to, rather than just ripping into things with no knowledge of proper workings and pitfalls, so I am very thankful and grateful for you to take the time to help me with my questions.  I also saw another post from you in another area and I wish you well today.
Sincerely,
Joe


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## Bandit03 (Mar 12, 2012)

Good morning Paul,
Just to let you know, I cut a hole in the wall between the bedroom and kitchen 12"X12" and installed return grill covers.  What a difference!  Can't wait to see what this does for the electric bill, but I am very satisfied with the results so far!
Thank you again!
Joe


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