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peterfeddersen 01-30-2009 03:29 PM

Cold Air Return Question
We are currently combining 2 rooms on the main floor. We had to give up a cold air return from the second floor which whas located in the wall we removed during the renovation.
There is realy no viable way of repacing this cold ait return on the second floor. We have now 2 returns on the second floor instead of 3.
The contractor does not seem to be concerned about it.

Does anybody have any expierience with that or knows of any possible negative consequences which may result??? Any suggestions would be

Peter Feddersen

Hube 01-31-2009 07:21 AM

Peter; you say there are still 2 returns on the second floor.
but how many returns are on the main floor?
What size is the duct/passage from these returns?

also, what amount of supply air is involved on each floor.

Ted 02-02-2009 06:51 PM


A quick test is to find out if the system is hurting for air circulation. After running the cooling system for about 20 minutes, measure the air temperature at the point where the air is going back to the indoor system, measure the air temperature coming out of the indoor system. Generally, the temperature drop should be about 20 degrees F between the 2.


peterfeddersen 02-03-2009 04:58 PM

Cold air return

Thank you very much for your responds.

It took me a while to figure out how the sytem works in order to come back to you.

(:rolleyes:First time ever user of a forum.- Rather interesting!-)

First of all, I want to know if there is a real science to this?

Is ther a mathematical formular to Cold Air Returns versus Warm Air Outlltes?

We gave up one Cold Air Return on the second floor and have now only 2 left up there.

On the first floor we still have 3 cold air returns. There are no Cold Air Returns in the basement.

It did not made much or any difference so far.

Is anything to be aware of it in the future?

Perhaps alocating cold air returns etc is not that crutial after all ?

I will enjoy seeing your comments and advice.



Hube 02-04-2009 07:35 AM

For a ducted forced air system to perform properly and efficiently, there must be adequate RETURN air coming into the unit in order to get the proper amount of SUPPLY air out.
Cutting off this one return to the upstairs could have a adverse effect on the air supply and comfort to some areas of thisupper floor.
However, there may not be any noticeable change in the area at all. It all depends on how the duct system was sized at the start .
Only a Hvac pro, with the proper air measuring instruments will be able to tell you what's truly going on.
Good luck.

peterfeddersen 02-04-2009 02:30 PM

Thank you for your advise. This is very helpful !

I will monitor and observe things. Perhaps it is not as crucial as I thought. We will seek profecional advise , as you suggested, should the need occur.

For a first time user of a forum, this has been a rewarding expierience .



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