Why is My Crawl Space Wet After New HVAC Install?

It is common for homeowners to experience extremely wet crawl spaces after installing a new heating and air conditioning system. In the warmer, more humid parts of the country, it is quite common to have the HVAC system running way colder than the previous one.

Moisture can find its way into crawl spaces even when HVAC systems are replacing fairly new systems. This article answers the question, “Why is my crawl space wet after I upgraded my AC?”

Upgrading HVAC is a Good Thing

It makes sense to update your heat and air system to save energy and keep your home more comfortable. High SEER-rated products are available from many HVAC contractors. You will be able to cool your home faster with these units, while pushing out air that is colder than your previous unit. But therein lies the problem.

Why is Cold HVAC Air Bad for My Crawl Space?

If you are like many homeowners, you may replace your AC system but attach it to the same duct-work with the same insulation in the same vented crawl space. Replacing AC systems can be quite expensive. I had the pleasure of replacing two in the past month. My first AC replaced was a 3-ton combination outside unit that was over $6,500. The other is just the outside unit on a split system that was almost $4,000. Because these units can be expensive most homeowners do not have the money to update the ducts or encapsulate the crawl space.

Consequences of Cold Air and Humidity Interactions

The cold air that is being pumped through the duct-work is causing the ducts to be colder than the previous unit. When a warm humid vented crawl space allows hot humid air to move into the crawl space unchecked. That warm humid air hits the very cold duct-work and condensates. The condensation makes the duct-work insulation and floor joist insulation very wet. Both will trap moisture and add to the humidity levels of the crawl space. The floor joist insulation leaches the water into the wood as the wood absorbs the excess humidity. Both are creating wood so wet, it will support mold and wood decay fungus.

New Ducts May not Fix a Wet Crawl Space

Installing a new AC system and replacing the duct-work normally does not keep the crawl space from getting wet. Unfortunately, the R-value assigned to HVAC duct-work is not high enough to combat the condensation problem. Most ducts are sealed pretty good during install but air leaks from duct-work can increase condensation around the leaks.

Flexible Ducts vs Hard Ducts

Flex ducts are more resistant to condensation versus solid ducts made of sheet metal. Flexible duct-work contains less metal to condensate but that does not make them immune to creating a moisture problem. We have seen wood condensate in a crawl space where the dew point was extreme enough to create major moisture problems.

How to Fix a Wet Crawl Space After New AC

When you have your new air conditioner installed, consider updating the ductwork, but make sure to control humidity in the crawl space. In the event that encapsulating the crawl space isn’t possible, install a crawl space dehumidifier. The Aprilaire E-Series dehumidifiers operate on dew point and regulate crawl space moisture. The HVAC system will be able to cool your home without creating a crawl space moisture issue or worse a mold issue.

Seeking Professional Assistance for Your Crawl Space

HVAC contractors install dehumidifiers, but if yours does not, you can do it yourself or call Crawl Space Ninja for a quote. Later, I would recommend a full crawl space encapsulation. After all, part of updating the HVAC is to save money and make your home more energy efficient. Crawl space encapsulation will add to the comfort and help improve your indoor air quality.

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Do you need help with mold removal, crawl space encapsulation, crawl space insulation, vapor barrier, waterproofing, or controlling humidity in your crawl space and you live in Georgia, Delaware, North Carolina, South Carolina, Tennessee, Ohio, or Kentucky? If so, please contact us to schedule your assessment. Also, let us know in the comments below if you have an idea for a new blog topic.

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