How to Inspect, Clean & Seal Air Ducts | DIY Ductwork Inspection

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Posted June 1, 2017

It is important to inspect your air ducts at least once a year. Ensuring your ducts are free from damage and contaminants will improve air quality and the overall efficiency of your HVAC system. Though it’s always a good idea to have your ducts professionally inspected annually, there are several basic maintenance steps you can perform on your own.

Catching small problems before they become larger issues will ultimately save you money in repair work and keep professional inspections to a minimum. Learn how to inspect your air ducts for air leaks and cleanliness.

Inspect Ductwork for Air Leaks

Materials Needed: When inspecting your air ducts there are a few basic tools you will need. Grab a screwdriver, a flashlight, some rags, and a digital camera (or smart phone with flash). You’ll also want to have some HVAC aluminum foil tape (NOT duct tape) or mastic sealant (specifically for duct work) on hand in case you need to patch up a leak. Don’t forget to dress for the job. Wear clothes you don’t care about and rubber gloves if you don’t want to dirty your hands.

Main Unit: Your first stop will be the main unit and its large ducts (which are connected to the branch ducts that run throughout the house). One side of the duct system blows air through the branch ducts while the other side pulls air in.

Turn your HVAC system on and feel around all air duct connections for any air leaks. Try wetting your hand a little to add extra sensitivity to your ability to feel for air leaks. You can also test for leaks using an incense stick or thin piece of toilet paper; if the paper sticks to, or blows away from an area where any two pieces of metal are joined together, you have a leak.

Branch Ducts: If there are areas in your home where ducts are visible (usually in the basement or attic), these should be inspected next. Check the insulation surrounding the ducts for any damage including torn pieces, damp spots, or mold. A wet area would indicate blockage and an indoor air quality concern, which would mean the section needs to be cleaned. If you notice damage to your insulation or any mold or moisture problems, contact your local technician to fix your ductwork.

Basically, you are trying to feel (or see) any air movement around your duct seams and connections. While you are testing for air leaks, inspect your air duct insulation for damage and wet spots.

How to Seal Air Ducts

Air Duct Leak Repair: When you discover an obvious leak coming from the main unit ducts, repairing it can be very easy. Aluminum foil tape and other heat-approved tape is great for leaks on a flat surface where two pieces of metal are joined together. Look for the Underwriters Laboratory (UL) label when purchasing. Before you do anything, grab your rag and make sure that the area is clean before applying either mastic sealant or foil tape.

After you have cleaned the surface, simply place a strip of the aluminum foil tape over the leak or use your mastic sealant and a paint brush to seal it. Use the mastic sealant for leak areas that would be difficult to close with the foil tape.

As a general rule, mastic sealant is more effective than any duct tape. It will last longer and is easier to apply. The only negative is that it isn’t effective for leaks larger than 1/4 inch and some people may find it unsightly.

In cases where the gap is larger than 1/4 inch, use aluminum foil tape combined with mastic sealant.

Additional Air Duct Sealing Tips:

  • After sealing air ducts in the basement and attic, you will find that both areas will become colder. If you do not have proper insulation in your attic and basement, consider insulating both. It is also recommended that you have your pipes insulated in both areas. Contact a professional contractor for solutions to your attic and basement insulation.
  • If you have converted your attic or basement into living areas, call a professional to install both supply and return ducts into the space.
  • Make sure your ductwork insulation has a proper vapor barrier to avoid mold and moisture problems.
  • Test your CO detectors to alert you to any carbon monoxide problems.
  • When repairing or installing ductwork, always consult an HVAC professional first. Only qualified contractors should perform changes to your duct system.
  • DIY duct sealing only goes so far. If you really want to seal all of your air ducts, you will need to contact a professional. Today’s technology enables you to seal your entire air duct system from the inside.

Watch this video for more tips to seal air ducts:

air duct sealing problems and solutions


How to Tell If You Need Professional Duct Cleaning

Vent Registers: There should be a vent in most rooms in your home (either directly on the floor or the upper half of a wall). Unscrew the vent and investigate the inside of your ducts with a flashlight.

If you cannot see very far into the ducts, a digital camera with a flash is also a good option as it can capture greater depth. Search for signs of large dust bunnies, rodent feces, and mold. If you notice large amounts of dust and debris, or spot anything out of the ordinary, then you should schedule a professional inspection and duct cleaning. Unfortunately, DIY duct cleaning isn’t feasible for the average homeowner.

Stay ahead of the curve on duct maintenance and keep your energy bills low and your air quality high by inspecting your duct work every year. The longer you put off sealing and cleaning your air ducts, the worse your air quality and energy efficiency will become.

Learn more about DIY air duct sealing and cleaning from ENERGY STAR and the Environmental Protection Association (EPA).

If more than 5 years have passed since you last scheduled professional duct cleaning—or if you never remember having scheduled it before—call us right away for an appointment844-MyHiller

For more home comfort tips and tricks read our other blogs:

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