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dtran 01-05-2009 06:08 AM

Fresh air intake damper - Open or Closed?
I have a fresh air intake system installed on my HVAC with a manual damper. Should I open or close this in the winter/summer, or should I just leave it partially opened at all times? What would be best?


beenthere 01-05-2009 07:05 AM

Depends a but on what size it is.

Most times, they are grossly over sized.

You can probably turn the damper to 50% closed, and it will still bring in enough fresh air.

dtran 01-05-2009 03:31 PM

The diameter of the duct, or the length? (sorry I don't know much about this).

Also, does it matter on the weather outside? I live in Canada where the winters are very cold and the summers are very hot and humid.

edit: One more thing, does this affect the humidity or moisture level in the house at all? Like if opened in the winter, would it dry out your house more compared to if it was closed, and in the humid summer, if it's closed, would your house be dryer than if it were open?

And btw, the intake duct has an insulated tubing around it that says 6" on it. The length of it is probably about 11' - 12' from the side of the house to the return duct.

yuri 01-05-2009 07:28 PM

I would recommend you have a damper on it and close it 1/2 way. It will drop the humidity in the winter which in some houses is necessary. If your house is very airtight it is good to get some fresh air in to breath. In the summer if you are in BC or southern ontario (very humid) you may want to close it to make the A/C work better. Not a huge problem in Wpg as it is usually around 50%RH.

dtran 01-05-2009 07:33 PM


So, just to clarify, 1/2 open all season long?

yuri 01-05-2009 07:40 PM

Yes. Check the hood for it outside for spider webs/debris a couple times a year.

beenthere 01-05-2009 11:02 PM

Yea, open/closed for both seasons.

In the winter the excess fresh air is decreasing your indoor humidity.

And in the summer it is increasing the humidity.

rossl56 01-06-2009 05:30 AM

Is the fresh air intake you are discussing taking air from outside the home, or is the air intake in the basement?

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