HVAC For Beginners

Duct Sealing

Benefits and Techniques

With our duct sealing guide, a homeowner can save energy and be more comfortable. This guide will look at ways to stop air from leaking out of a forced air heating/cooling system. The typical unsealed duct system will lose about 20-30% of the air that is being conditioned. Therefore, this air does not make it to the rooms that need it and so more air has to be heated or cooled to maintain your comfort.

Benefits of sealing

A properly sealed duct system will improve the comfort level in the home. It ensures that the conditioned air gets to where it is needed. It will also improve the air quality of the home by preventing dirt and contaminants from being pulled into the hvac system. Air duct sealing will also save energy as less air will need to be conditioned.

Methods of duct sealing

The most common method of sealing is by applying a metal foil tape to the ducts to cover the holes and connections. This is an easy method that the typical homeowner can do in a weekend project. It is relatively inexpensive but there will be parts of the system that are inaccessible and so it will be less effective than other methods. Another method which is more commonly used by pros is the use of a duct mastic. This is a paste that is brushed onto the ducts and it hardens after a short time. Once again, there will be inaccessible areas which will reduce the effectiveness and the chemicals may not be environmentally friendly. The latest method is duct sealing by injection and is performed by professionals with special equipment. A home sealing machine is connected to the supply and return ducts and an initial pressure test is performed. This tells the homeowner what the initial leakage rate is for their duct system. A special patented sealant is then sprayed into the duct system through the machine and it sticks to the holes where the leak is happening. The sealant builds up in the holes and closes them but does not build up in other areas of the system. A final pressure test is performed to measure the leakage rate to see the overall effectiveness of the process. This method will provide the most airtight system and it can be used on metal, ductboard and flexible ducts. The sealant is non-toxic which is better for the home and the environment. This process will be more expensive as it must be performed by a professional with the patented equipment.