It has been a very warm week here in Charlotte and I noticed that one of the supply air vents in a bathroom, had a bunch of condensation on it, to the point that it was dripping water onto the floor. I immediately thought that I am not the only person with this problem, and wanted to share the reasons why this happens.

Where Does the Water Come From?

Before you start reading this, go and get yourself a big glass of Ice Water, and set it onto your desk. By the time you are done, you will have effectively done the same thing that your vents are doing... Condensing!

As the cold air coming from your central air conditioning passes through your ducts, it gradually warms up. There is a point where the colder and warmer air actually product water, known as the dew point. The higher the humidity, the higher the dew point, or point at which air condenses and forms water.

What Causes It To Condensate?

There are several things that can cause the cold air to condense into water, but the most common in household HVAC systems, is poor insulation of the ductwork. In my case, I had a bathroom window open, which allowed the outside heat and humidity to enter the room. The minute the cool air left the vent into the bathroom, it condensed and formed water drops on the supply vent.

If you don't have a window open, the only other thing happening to you, is that the air is warming to the dew point, before it leaves your vents. Meaning, you have poor vent insulation or if the vents run through your attic, its too hot in there!

How to Prevent Condensation on Vents

The first and most common way, is to climb into your attic or crawl space and check the insulation on your vent. Just a few inches of missing insulation near the vent boot (Where it meets the wall or ceiling) can allow condensation to form and if not fixed, lead to much worse problems like rotted wood, drywall, or even mold!

Replace your old insulated duct with new R6 Flex Duct!

Replacing a run or two of flex duct is a quick and easy job that almost every homeowner can do in an afternoon! The benefits of pulling out 15 year old, wet and rotted ductwork can be amazing!

Another great way to reduce heat around your ducting is to install an Attic Vent Fan, or even a crawl space ventilator.

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