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Duct Hunt: Ductwork Problems and How to Fix Them

by Daniel Estevao on October 23, 2015

It’s duct season! How are the ducts in your home? Most homeowners never even think about the ductwork problems they may have. How would you even know anyway? The majority of your ducts aren’t even reachable, located mostly behind walls, and in your attic and crawl spaces.

how to fix ductwork problems

Although duct inspections aren’t needed all that often, over time, ductwork ages and develops leaks and other inefficiencies. In fact, about 20-30% of the conditioned air that moves through your ductwork is lost through leaks and holes (energystar.gov)! Your ducts may be in even worse condition.

Ductwork Problems

Forgotten about ductwork leads to a host of problems for your HVAC system, home, and family. Besides compromised efficiency, a dirty duct system can develop mold and other harmful indoor air pollutants that could exacerbate health issues. It’s important to inspect your ductwork at least once a year to check for excessive debris and air leaks.

Here are some common signs that you need duct repair, duct cleaning and/or duct sealing in your Washington home:

  • Rising energy bills indicate a growing problem with your HVAC system, insulation, or ventilation. If you have high utility bills, there’s a good chance your ductwork has something to do with it. The leaks and poorly connected ductwork releases your precious conditioned air into unused areas of the home. Additionally, if your duct system was poorly designed, it may be losing a lot of heating a cooling to unconditioned areas of your home, like attics and crawl spaces. The ductwork in these areas should be insulated because they end up losing a lot of heat in winter and gaining heat in summer.
  • Stuffy rooms that are difficult to heat and cool can indicate a problem with your ductwork and/or with your heating and cooling system. The duct leaks in your system are likely contributing to insufficient airflow. When the airflow in your HVAC system is unbalanced, you will notice cold and hot spots and certain rooms that simply won’t get hot enough or cold enough no matter how high or low you set the thermostat.
  • Banging, popping, wheezing, and whistling sounds could indicate a problem with your ductwork design. If you have rectangular ducts, the banging and popping could be the result of contraction and expansion of the metal when air flows through it. When your HVAC system turns on or off, you might here a banging or popping sound, which is completely normal. If, however, you hear constant noises, you may wish to replace your rectangular ductwork with round or square ducting. Similarly, a whistling sound could indicate undersized vent covers or holes in your ductwork. An HVAC professional like Pacific Air Systems will be able to perform a duct pressurization test that can pinpoint the source of your air leaks and what’s causing all these noises. A large bang that rings through your ductwork can indicate a problem with your burners. Similar to the explosion when you let the gas run in a barbecue and then press the ignition, your burners may have become clogged, which causes a delayed ignition and the resulting explosion in your ignition chamber. This means you have a problem with your fuel-burning furnace and need to have it cleaned and inspected by a professional right away!

Detecting Ductwork Problems

If you notice any of the above problem signs (or even if you don’t), now’s a good time to inspect your ductwork for air leaks and other inefficiencies. Although your problem may be with the original installation and design work, these tips will help you decide what you should with your aging ductwork. Let the duct hunting begin:

  • Look for any cracks, gaps, or holes in your ductwork. Pay careful attention to the seams and connections, and where they meet walls, floors, ceilings, vents, and registers. These are the areas most prone to air leaks in your ductwork. If you have flexible ducts, make sure they aren’t tangled.
  • Listen for banging and other sounds in your duct system. Loud noises are a sure indication that something is not right, whether it is with your HVAC system itself or with air leaks and bad design.
  • Feel for proper airflow coming out of all your vents and registers. The air should be coming out at a consistent rate and pressure.
  • Test for air leaks using an incense stick, thin piece of toilet paper, or your wet fingertips. If you see the smoke or paper moving erratically, or if your finger feels cold, you have just detected an air leak! Test for air leaks around all your duct’s connections and seams. Most likely, you will have small amounts of air leakage in all your duct joints and connections.

Fixing Ductwork Problems

After running your DIY test for air leaks around all of your exposed ductwork, you are now ready to repair your air leaks! Although much of your ducting is enclosed behind walls and isn’t accessible for a casual inspection, you can do wonders for your airflow, indoor air quality, and energy efficiency by taking the time to seal the exposed portions of your ductwork.

Materials needed: mastic sealant or HVAC aluminum foil tape, gloves, plastic putty knife, and a damp and dry cloth.

  1. After finding the source of your air leaks, take your damp cloth and wipe the area clean. Be careful of screws and other pieces of metal that could cut your hand. Make sure it is dry before moving on to step 2.
  2. Mastic is the preferred material for sealing loose connections in your ductwork. Prepare the surface first before applying the mastic sealant. Follow the directions on the container, but you can use a plastic putty knife, stiff paintbrush, or something similar to apply the material (similar to icing a cake). Wear gloves and old clothing in case it gets on you. The mastic should be about as thick as a quarter or nickel.
  3. Aluminum Foil Tape can also be used to seal your air ducts. If you do use this method, make sure the tape is specifically designed for ductwork. Do NOT use duct tape. Ironically, it does not work very well to seal air ducts.

Watch this video for more tips and insight for sealing the ductwork in your home:

For professional duct sealing that can seal your entire duct system from the inside, call Pacific Air Systems for Aeroseal duct sealing technology. Aeroseal sealant comes with a 10 year warranty and can seal all of your hidden and exposed ductwork without having to rip through walls and ceilings in under an hour.

Watch a This Old House episode for more information on Aeroseal duct sealing technology:

If you want more ideas for improving your indoor air quality and energy efficiency this fall and winter, read our other blogs:

We are your trusted HVAC and Indoor Air Quality specialists in the Tacoma/Lakewood area. Call us at (253) 292-3995 for your professional duct sealing and/or cleaning consultation today!

Since 1984, we’ve proudly served homeowners throughout Federal Way, Graham, Spanaway, University Place, Steilacoom, Sumner, Lakewood, Puyallup, Tacoma and Gig Harbor.

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