Is Slower Air Flow Sufficient To Dry Buildings?

I’m writing today  from the Okefenokee Swamp in South Georgia. 

Down here to do some exploring and fishing with my family. It’s kinda chilly down here. For South Georgia anyway.

Interesting how in the sun (radiant heat) it feels pretty warm here, even when it’s cold outside. As long as there is no wind. If there is wind though (convection), it feels downright cold. When we get out on the boat moving along it’s real cold. (Minnesota folks are probably shaking their heads but I’m coming to a point.)


So to keep warm even in the wind we put on a coat and hat and try to counteract the effect of the wind and stay warm. The stronger the wind though the more it gets under your clothes and chills you. There’s a drying point in that.

Evaporation requires energy transfer. Heat up water and you are going to improve the potential for that water to evaporate. Primarily we do that through convective heat transfer, warm air flow.


Want to learn about how to calculate evaporation potential? Watch this Quick Tip Video!


Like the wind, airflow creates greater energy transfer at higher speeds. Just like a cold wind makes you cold, warm airflow will warm wet materials. The faster the airflow, the faster the energy transfer.

Additionally, like a high wind that gets under your clothes and chills you, faster airflow will force its way into the cracks and crevices of building assemblies much better than slow airflow to get to the water we are there to remove. That’s because there is a direct connection between air speed and air pressure.



So why all this talk?


Because a good analogy helps to teach and we weigh what anyone says against what we already know.

There is misinformation that states slower air flow is sufficient to dry buildings. Particularly late in a project.

While some material drying research may indicate that, it is simply not the case for drying the complex assemblies.

We dry complex assemblies! These building assemblies have coats, so to speak. The high pressure from high speed airflow is required to get into complex assemblies and flush out moisture just like a high wind gets right around our coat.

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As you hear suggestion through fancy talk, or direction, that we don’t need much airflow to dry, don’t be suckered in:


Reject that.


It is a misapplication of good information with a potentially dangerous downside for our industry if it were to be believed.

That kind of reasoning will leave insurance companies incorrectly thinking we don’t need as many air movers.

I’m still recovering from fighting the fight together with over 2000 others of us that got us to the effective S500 formula for air movers that we have today. Please don’t start that battle again. Thank you to all of you who got involved back then! I am in your debt. Take a moment to remember 2013 to 2015 and thank the ones who got involved.


So what do you do?


You set air movers at the rate specified by the S500, and leave them running on high till those assemblies are dry.

I’m about to head back out on the water and I’m gonna bundle up. It’s gonna be windy.


Looking for more water damage restoration training? Check out the Reets TV Streaming Video Library, and browse our 150 + videos. Get your free trial today!

Jeremy Reets

Jeremy Reets started working in water restoration in the family business in 1990.  He is known as the innovator of the TES/ETES drying systems, a discipline of drying called Directed Heat Drying™ and the Evaporation Potential formula.

Jeremy opened Reets Drying Academy and flood house in 2005 to provide water damage restoration education.  Jeremy and his brothers also own Champion Cleaning Systems, Inc., a multi-million dollar water damage mitigation company that his family started in 1970.

In 2011, Jeremy began ReetsTV, a series of online water restoration training packages designed specifically for restoration company’s everyday needs, another first in the Industry. 

Today, Reets Drying Academy provides online training for water damage restoration, mold remediation, mitigation estimating and fire damage restoration.


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