Why Do Ducts In Attic Collect Water

The last usual cause for condensation on a duct system is if the ducts are not properly hung or they are touching each other.

Why do ducts in attic collect water.

Ducts belong inside your home s conditioned space. Ductwork located in an attic must be hung properly so that the insulation can do its job. The most likely explanation for the water in your ducts is that warm interior air is entering the ducts during the winter and the moisture in the air is condensing on the interior of the cold ductwork. During the heating season unused air conditioning ducts located in unheated rooms can collect moisture.

Condensation forms when the water vapor in the air drops out of suspension and condenses into a liquid form. In more cases than not a 3 ton ac with the ducts in the attic has a ton or so of load that s just from the location of the ducts in the attic and the associated duct gains leakage etc. Excessive condensation can also create conditions favorable to mold or mildew forming in areas surrounding the duct itself. Condensation forms when warm humid air comes into contact with a colder surface like your air conditioner s ductwork.

The remaining 2 tons of capacity is at least 1 5x oversized for the actual 1 load. Installing ducts in a vented unconditioned attic is always a bad idea. When ductwork is touching it forms a very cold spot where they are touching thus condensation begins. Each time the heating or cooling system operates the air moving through the ducts can blast millions of mold spores throughout the house.

Occasional condensation on a c ducts is not a problem but keeping an eye on the situation is recommended. Martin holladay editor of green building advisor responds. There are two possible ways to solve this problem. The water in the ducts can initiate the growth of mold.

The colder the air the more likely it is that water will condense. Persistent ductwork sweating may eventually lead to water damage. Moisture can also collect in the summer if cool air passes through a duct in a room that isn t air conditioned. Excess humidity in the attic or crawl space can also encourage condensation on the inside and outside of ductwor.

The first is to keep your ducts warm.