In this short Q&A podcast episode, Bryan answers Howard's question about how to deploy a dehumidifier (dehum) in a sealed home. He addresses things like location and fresh air requirements in green-grass markets with high dew points. 

Before deploying a dehumidifier, you will need to know about the climate, the structure, and the client's complaints, budget, and comfort goals. You need to make sure the HVAC system is properly installed; the most common obstacle to proper dehumidification is oversizing. HVAC systems need a cold coil to pull moisture out of the air, and we need adequate (but not too much) ventilation in the structure before deploying a dehumidifier. Common obstacles include leaky structures, venting exhaust air into the attic, and constantly running exhaust ventilation (like range hoods or bath fans).

Bryan's preferred setup is to have a dedicated dehumidifier just for the sealed attic, though you can make the HVAC do this if you plan it out during the construction phase. If you bring in outdoor air, you should plan to bring it in through the dehumidifier, but that can interfere with attic dehumidification. You can either use two dehumidifiers or use powered dampers to dehumidify either the attic or house at different times.

You can consult the expertise of groups like the HVAC Grapevine and manufacturers like Santa Fe Dehumidifiers. HVAC School also has a range of dehumidifier topics; you can search for videos, podcasts, and tech tips on the topic in the app.

 

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