leaky air duct

Fixing A Leaky Air Duct

The air ducts run from the central air conditioner to the corners of your home. They are intended to supply cold air from your system to each room in a more or less consistent way. Because they are installed in your walls or attic, ducts are usually safe from damage or leaks.

As the air ducts beneath your walls age, leaks from an outside source or a loose bolt connecting two sections of duct can happen. A professional contractor can repair an air duct leak by replacing the broken bolt, adding duct mastic, or inserting a fitting piece over the hole. Before contacting a professional to repair an air duct leak, it’s essential to understand the most typical signs of air duct leaks.


How to Conduct a Visual Duct Leakage Test

You may do a visual duct leakage test if your ductwork is visible. Many houses in the United States are heated and cooled using push systems. The supply and return vents draw and push air into and out of the system, eventually heating or cooling the household. Ductwork is often located under the living space in most homes that have push heating and air conditioning.

These vents can occasionally be accessed through the basement and crawl space ceilings. In general, it’s easier to detect a leaky vent in a basement where there’s plenty of room to walk around and fix it on the spot with high-quality foil tape or mastic. While foil tape is simpler to work with, cement, such as mastic, will soak into the air leaks and provide a better air seal.

When you’re in your basement or crawl space, carefully move your hand to feel for any air escaping the vents. If it’s not too noisy, you could hear a hissing sound. Mark the location and continue moving around the metal ductwork. Part of the ducting is made up of metal trunks that link to one another.

They are frequently held by metal cleats, which, if not airtight, might be the source of a duct leak. Pay particular attention as you approach joints where the venting may change direction. The majority of air leaks in HVAC vents occur where the joints meet.

It might have been loosely tightened, or the connection could have been stuck and the HVAC installer just left it that way. Mastic would be the ideal way of sealing such an air leak since it will fill that space and the surrounding areas. When the cement-like material hardens, it expands and fills the cracks causing the air leak.

The low ceiling makes it difficult to navigate when evaluating the venting, as per a visual duct leakage inspection in a crawl space. It’s absolutely worth trying to identify a leaky vent if your system isn’t operating effectively and you suspect leaking ductwork. You may get a bit dirty down there, but if you locate an air leak, you may save a service visit by repairing the problem yourself. Keep in mind that the problem isn’t usually caused by a single leaking vent.


When My Vents Are Insulated, What Should I Do?

When your ductwork is covered in insulation, the metal vents are difficult to reach, even if they are visible in a basement. It’s possible that you have an air leak in your ducts that you’ll never notice since it’s concealed behind the insulation. Other times, you may detect the insulation being blown down as a result of an air leak and be able to pinpoint the source of the problem.

To check for air leaks, you’ll need to remove the insulation to have access to the metal vents. You can return the insulation when your inspection is over. Ensure that any treatment done to the vents is totally dry before reinstalling the insulation.


Leaks Can Be Seen In Visual Ductwork, But What About The Rest Of The House?

This is a challenging problem to solve, and you may need to hire a professional duct leakage specialist to help you. A pre-test is performed before the real test to provide an accurate assessment of how the existing system is functioning in comparison to the duct leakage test that will be performed next. 

Once all of the equipment is in place, the test will be conducted by blowing air into the ductwork using a fan to see how much air is escaping. Because the equipment is connected to a computer, it will provide a reading that will determine the system’s performance and identify if air is leaking through the ducts.

If the results are satisfactory, the task is completed. If the results suggest that air is escaping the ductwork, the technician will apply a sealant. The chemical that must be used is a milky, rubbery liquid that is sprayed into the supply and return ducts in an aerosol. The sealant is a vinyl acetate polymer liquid that is sprayed into the duct work and fills any holes or leaks it finds. When a hole or crack is discovered, it will naturally fill in that area and form an airtight barrier that will prevent any air from escaping.

The testing equipment is connected to a computer during the air duct sealing procedure, which measures the amount of air escaping the ducts in CFM (cubic feet per minute). The technician doing the duct leakage test will be monitoring the program on a tablet while the aerosol treatment is happening, which will tell him of the improvement in overall system performance. When you place your palm over the vent and experience a greater rush of cold air, you’ll notice the difference.

In order to properly clean air ducts, equipment must be put at various places across the vents. Making a circular cutout in the metal trunks and placing the air duct cleaning equipment there is how this is accomplished. After the procedure is over, the air duct cleaning company will use a metal plate and screws to close the opening.

The issue is that the circular cut out can leak a substantial volume of air, causing your HVAC system to function poorly. There are also holes formed by metal screws that must be taken into account for possible air loss. The right technique to seal the hole is to ensure that no air escapes by applying a layer of mastic to the metal plate for an airtight seal. This is frequently neglected by air duct cleaning companies, resulting in more and more air escaping over time. Always call a licensed air duct cleaning technician who will thoroughly inspect your ductwork for any air leaks.

Any homeowner will be disappointed if their air conditioning system performs poorly. You might have a brand new HVAC system built and your house would still not cool down for unknown reasons. Other times, certain areas of your home may not cool down at all. If this is the case, you should examine your ductwork for suspected air leaks. The conditioned air may not be reaching the living rooms owing to air escaping the vents.

The goal is to identify the air leaks and thoroughly seal them using a substance that creates a great air tight seal. If you have performed a comprehensive check to the best of your ability and the problem has not been remedied, you may need to contact a duct leakage expert who can detect leaks beyond a visual inspection. You’ll be astonished at how much of an improvement fixing leaky ductwork can make on the operation of your HVAC system.

At Calvey Heating and Air, we offer a service where we can inspect your ducts with a special camera. This inspection can help us find the leaks that are affecting your heating and cooling as well as energy bill. If you notice that your air conditioner and heater are working non-stop, but your home is not acclimating, you may have a duct leak. We can use our diagnostic tools to find the problem and fix it for you. Contact us today and schedule an appointment!

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