# Help with Return-Air Question

• posted on September 25, 2004, 12:32 am
I had an electrical forced air heating/cooling unit that I replaced a couple of years ago with a gas unit. However I kept the original duct systems intact with no changes.
The original ductwork has a return air register located in a corner of my kitchen floor. The other return air openings are located on my second floor along the wall. Two openings along the wall about 6 in. by 24 in through the same wall cavity.
I would like to redo my kitchen floor, but the floor opening for the return air is in the way. Can I just block this opening and rely on the return air opening from my second floor?
How can I calculate or estimate how much return air opening is needed for the system? Can I just take more return air from the basement where the unit is located ? or just add an opening on the main floor of the same wall with the return air on the second floor?
Thanks.
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• posted on September 25, 2004, 5:01 am

This is Turtle.
No --- Awww No ---- Well awwww Not realy without messing up things.
The Location and size of the return plays a big part in the air flow and working ability of the system. If you can't reinstall the return in the near area of the kitchen where it was. You will need a Manual D calculations to relocate the return as to where and size to take the place of that return register that was in the Kitchen.
Try to relocate the return somewhere near the kitchen like in the hall , other room, or maybe on the ceiling of the kitchen. Without the Manual D calculation. your going to have to find a place near the Kitchen to put it or get a Manual D calculation done.
TURTLE
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• posted on September 25, 2004, 5:09 am

Turtle,
It looks like I owe you a coke, pal.
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SVL

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• posted on September 25, 2004, 1:06 pm
What happens when there is a space with an air feed but no return at all? This is how it is in one of the spaces in our basement.
MB
On 09/25/04 01:01 am TURTLE put fingers to keyboard and launched the following message into cyberspace:

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<%-name%>
• posted on September 25, 2004, 6:42 pm

This is Turtle.
If there is no return avialiable for the air to return. it will either shuve it out the cracks of the room and go out side or just be dead head pressurize room just waiting for someone to open a door to let it out. If the room stays warm during the winter with the door shut. You shoving the air out the cracks of the room to outdoors or other rooms. It can never work right without a return path for the air to get back to the air handler or furnace.
TURTLE
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• posted on September 26, 2004, 3:15 pm
[original post is likely clipped to save bandwidth]
wrote:

Yup, if there is insufficient return it isn't every going to work. Also, expect nasties like fan limit switch cycling and shortened heat exchanger life due to excessive thermal stress.
As you say, it won't ever work right. Also, it probably will shorten life of the equipment.
gerry
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gerry misspelled in my email address to confuse robots
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• posted on September 25, 2004, 8:58 pm

Then the air has to pass under the door threshold ( if theres a door at all ) to get to the nearest return.
Closing the door ( or adding one ) will help conserve heat in this kinda situation where you have a room or space that are seldom used, just shut the door if you dont want to heat the area as much as the rest of the house......
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SVL

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• posted on September 25, 2004, 6:16 pm
Thanks. My kitchen and the dinning room is one common area. One of the walls in the dinning room is the same wall with a return air grille in the hall way upstairs. Could I create an opening in this wall will an area same size as the kitchen floor opening? It will be about 12 feet away from the floor opening. Does it matter if the new opening (if this is possible) to be closer to the floor or can I move it closer to the ceiling?
Once again thanks for your help.
wrote:

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<%-name%>
• posted on September 25, 2004, 8:15 pm

This is Turtle.
i wrote up a good reply to you e-mail and found out it would not send it. SO here is the short version to the newsgroup.
Yes the return at the top or bottom of the dining room and kitchen will be ok.
Yes move the return grill 12 feet but make sure it stays in the Dinning Room and Kitchen area.
If you like to discuss it more, just e-mail me.
TURTLE
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• posted on September 25, 2004, 5:07 am

Okay your post has sat out there quite a whilenow unanswered, so I will give a crack at answering it........
== Blocking it off is not advisable, the location and size of the returns are generally just as important as the location and size of the supply registers and its to be assumed that that single return in the kitchen serves to circulate pretty much the whole upstairs portion of the house, and blocking it off will affect circulation of the entire system, both upstairs and down..........
Now if you want to calculate, you need to probly call in a pro--sorry, but thats just the way it is because its pretty difficult to do this sort of thing over the internet, we cant see the layout of the place, much less even determine if the ducts already in place are adequate.
...BUT...
If theres other issues like perhaps its always cold in the living room, while too warm in the kitchen for instance, relocating that return might add to the overall comfort........
Think of it this way.........If you block off that upstairs return such that all the air has to go down the staircase to get back to the furnace, ( even if you add another return downstairs ) then what happens if somebody shuts the door to the downstairs ???--this means the upstairs wont get any heat at all, except what can be reheated after passing under the doow threshold.........
So again, without a thorough study of the place and the existing mechanicals, its a long shot to expect to get much in the way of usefull info here from a newsgroup.
Cheers,
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SVL

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• posted on September 25, 2004, 6:25 am
I would not change it.
Dave