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Should returns be installed in encapsulated crawl space and attic?

440magnum | Posted in General Questions on

I have recently moved into our new construction home and as I have slowly learned about conditioning crawl space and attic I have questioned if my contractor did it correctly. As far as the crawl space it initially had no air movement. (Completely sealed). During inspection the county inspector advised 1 or 2 air vents to be installed off of the  HvAC’s main runners in the crawl space and attic. 

And here is my question.. should I close or tape the vents that the inspector had us install? Or install return vents so not only it blows fresh air but returns it too. 

Would a simple floor and ceiling vent equalize the pressures and return some of this air?


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  1. charlie_sullivan | | #1

    You are correct that it doesn't make sense to blow air into those spaces without a way for it to return. I think simple floor and ceiling vents are a fine solution. So is a small return in each. You need very little air flow to each, so the opening in the supply vents can be mostly closed off. You can monitor temperature and humidity in those spaces to make sure the air flow is adequate.

  2. 1869farmhouse | | #2

    Is the home/crawl space more than 20 years old?

    Maybe in any case, but especially if so - I’d install an exhaust only ventilation fan and then just cut in a passive vent or two in the living space. This is generally the code, but even if it isn’t, it’s going to keep all the nasties that reside in crawl spaces out of your living space.

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