How to Seal a Heating Duct

What You'll Need
Sheating tape or a roll of metal
Expanding spray foam insulation
Brush or trowel
Rubber gloves
Ladder (optional)

Heating, ventilation, and air conditioning (HVAC) employ the use of a heating duct in the process of removing and delivering air. This is done through exhausting air, supplying it and returning it. Through the heating ducts, thermal comfort and indoor air quality is kept in check thereby ensuring that people live in their homes and offices comfortably.

Sometimes, it becomes hard to tell if ducts need repair but the following signs are enough to prompt action:

  • If the rooms become too cold or too warm.
  • If the utility bills are high over the winter and summer seasons.
  • If there is little or no airflow in some rooms.
  • If you keep changing the air filter severally in a month.
  • If there are dusty streaks in duct connections and registers.
  • If visible ducts do not show any form of insulation.
  • If there are kinks and tangles in flexible ducts.

It is important to know how to seal the heating ducts and this is how to do it:

Step 1: Check the Heating Ducts

Most of the times, leaking ducts happen to have been disconnected. You should check them out and reconnect those that have been disconnected.

Step 2: Check the Heating Ducts for Leaks

Heating ducts may be dysfunctional due to the presence of leaks. To find out if there are any leaks, turn on the cooling and heating system. After this, Use your hand to feel the leaks.

Step 3: Seal the Leaks

Once you have established that there are leaks, use a foil tape or a mastic tape to cover them. If there are gaps in the ducts, use the spray foam to seal them. It is important to clean the joint thoroughly before applying the mastic tape. If you put the mastic tape when the joint is full of dust particles, the tape will not hold firmly and the leaks will resurface soon after.

Step 4: Reinforce the Mastic Tape

Using a mesh tape, reinforce the mastic tape to ensure that it holds firmly. This should happen on joints as they require more strength if they are to stay in place. Gaps larger than ¼ inches require reinforcing as they may not be firmly sealed using a mastic tape alone.

Step 5: Insulate the ducts

You must insulate the ducts to prevent further leakages especially those that are in crawl spaces. Poorly insulated ducts lead to leakages. Use an insulation material that is R-6 as it is strong enough to hold them together for longer.

Step 6: Hire a contractor

This should be done in instances where you cannot access the ducts.

Note: Duct tape must never be used to seal the heating duct leaks since it dries up and cracks with time. This leads to bigger leaks that will end up costing you more money and making it more difficult for repairs to be done.