Handling Duct Load with a Foam Encapsulated Attic

When the attic is foam encapsulated it is assumed to be a conditioned space. So, the Duct load will be 0.

Reality is that the foam insulation may have some areas with breaks and holes and the outside air will leak through. Additionally attic will have some heat gain in the afternoon, and the amount will depend on the shingle colors, etc.

Instead of accepting the 0 Duct Loss and Gain when the duct is run in a foam encapsulated attic, manually override the Foam attic duct loadnumbers and give it a percentage of the load. Typically 3 – 5% should cover it.

Check the box in the Manual Override column, the type in the percent you want and then click on the Refresh button.  The system will make the latent load consistent with the latent you should expect for the area.


This tip comes to us from our technical advisor, Lewis Cooley.


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