Q&A - How to Deploy a Dehum - Short #211 · HVAC School - For Techs, By Techs summary

Key takeaways

Dehumidifiers are key for managing moisture issues in sealed homes, especially in humid climates.
Proper HVAC setup is crucial to avoid common issues like oversizing, which affects dehumidifier effectiveness.
A dedicated dehumidifier for the attic is often preferred to improve air quality without mixing with living spaces.
Ventilation strategies should be carefully considered to prevent excessive moisture intake from outdoor air.
Community resources and expert advice can significantly enhance the effectiveness of dehumidification strategies.

Summary

Understanding Dehumidifiers in Sealed Homes

In this episode, the host addresses a key question from Howard regarding the deployment of dehumidifiers in sealed homes, especially in hot and humid climates. It is essential to first understand the specific challenges posed by the region, such as high humidity and temperature levels contributing to moisture problems. Before deploying a dehumidifier, it's crucial to ensure that the HVAC system is installed correctly, as oversizing often hinders effective dehumidification. Proper settings, cold coils, and adequate ventilation are also important factors to consider.

Best Practices for Dehumidifier Deployment

The host prefers a dedicated dehumidifier for the sealed attic to avoid mixing attic air with house air. While some practitioners use the HVAC system to handle attic humidity, the host emphasizes the importance of starting with a dry attic during construction. If outdoor air is introduced, it should ideally be cycled through the dehumidifier to maintain comfort and prevent condensation issues. Solutions may involve two dehumidifiers or a system utilizing powered dampers to manage air movement between the attic and living spaces.

The Role of Ventilation and Outdoor Air

Ventilation plays a pivotal role in managing indoor air quality and moisture. The episode discusses the balance needed to avoid excessive outside air influx, which can lead to higher humidity levels. Techniques for effectively introducing outdoor air, such as ducting methods, are highlighted to ensure that the air integrates seamlessly with existing air streams without causing condensation. Best practices and expert recommendations from HVAC organizations are suggested for optimizing dehumidifier performance.

Community Support and Resources

Listeners are encouraged to tap into community resources for support and best practices regarding dehumidifiers. Groups like HVAC Grapevine and manufacturers like Santa Fe are noted as excellent resources. Additionally, the HVAC School platform itself offers a wealth of information including videos, podcasts, and technical tips on dehumidification. It’s stressed that the deployment of dehumidifiers is not a one-size-fits-all scenario; it depends on various factors including budget, market conditions, and specific client needs.

Show notes

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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Q&A - How to Deploy a Dehum - Short #211