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Community and Q&A

Condensation on Intake Ducts

zox20 | Posted in Energy Efficiency and Durability on

I will be building a house at 4000′ elevation, zone 2B outside of Tucson. It will have an ERV system and make up air system. The intake air for both will immediately enter a conditioned/insulated attic. Is there a chance of condensation forming on the inside or outside of either intake duct?

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  1. Expert Member
    BILL WICHERS | | #1

    If there is a risk of the temperature of the intake duct surface being below the dew point of the outdoor air, then you could have condensation forming. I would expect the usual humidity levels outside Tucson at high elevation to be pretty low, and very dry air is less likely to cause problems here. If you are concerned, insulating the duct provides a little insurance, and pitch it to the exterior vent so any condensation will drain out.

    I think you’re probably unlikely to have problems here though since the outdoor air probably won’t have enough moisture content to present a significant risk of condensation.


  2. zox20 | | #2

    Thanks. I will pitch to the outside. Where I'm building gets a little over 20" of rain per year. I've had condensation form on the bottom side of a metal roof over an open patio during winter rains.

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