A Simple, Step-by-Step Guide to Fixing Leaking Ducts

Most ducted air conditioning systems work by channeling cool air through a series of ducts and vents into multiple rooms in your home. Think of your ducts as the highway that cool air uses to reach its destination. If your ducts are leaking, the efficiency of the AC unit is significantly reduced, and you will end up incurring higher energy costs. In addition, various rooms in your home may end up feeling hotter because cool air is not reaching where it needs to go.

There are simple steps that you can take to fix leaking ducts in your home. If your ducts and vents are easily accessible, this guide will give you a step-by-step outline to identify and seal your leaking ducts.

1. Start by looking for the leak

The first step is to identify where the leaks are. Turn on the air conditioning system and ensure that it is constantly blowing air (think of it as finding a leak along a water hose). Follow along the ducts and look for any loose connections or broken joints.

It is a good idea to begin in strategic areas such as near the furnace and registers or along supply ducts that branch off from the main system. These areas tend to be more prone to leaking because air pressure is higher. For instance, the air near the furnace is at a high pressure because it needs to circulate to the entire home. As a result, leaks can easily occur near this area.

2. Check the flex connections

Once you have identified the leaks, begin by checking the flex connections that hold the ducts together. Loose flex connections are the most common cause of a leaking air duct. Use duct tape to secure the connection in place and prevent air from leaking out.

If you notice any holes or seams in the ducts, cover those with mastic or foil tape. Mastic also comes in handy to seal holes in ducts. Add several layers, and ensure that they remain firmly in place.

3. Seal the leaks and insulate the ducts

Once loose duct connections have been secured in place and leaks have been covered, you should proceed to seal the ducts. Sealing can be done using foil-backed or mastic tape because they don't allow air to leak.

Use the tape to lightly wrap the ducts and cover them in the process. In addition to sealing, you will also insulate the ducts against losing cool or warm air when the HVAC unit is running.