5 Easy Steps to Install Flex Ducts 

Home heating and cooling systems typically use two types of ductwork: rigid metal ducts or flex ducts. Flex ducts are semi-rigid and much easier to work with than metal pipe ducts. You can install them wherever you expect minor movement, such as where the ductwork passes through an attic. They are also more forgiving if you need to make adjustments during installation. 

Understanding the process of installation helps you complete the HVAC setup with confidence. Also, you will save time and money by not making mistakes that require you to start the process over again. Follow these five easy steps, and you will have your new flexible ductwork up and running in no time. 

1. Determine Your Needs 

Your duct installation varies often. In one instance, you would need an all-rigid system. In another, you may want to use a combination of both rigid and flex. Other times, an all-flex system is adequate for the job. Determine your scenario by looking at the installation surrounding. It will dictate your choices. 

Whether you want to install the flex duct in the attic or basement also affects your decision. The different locations have unique access considerations you must remember when deciding. For instance, an attic installation requires you to work in a smaller, more confined area than one in the basement. 

Use rigid pipe ducts where you expect or think heavy objects move. For example, if you store holiday decorations in the attic, you need a more robust system to protect your ductwork. Flex duct systems are ideal when they are short. But use a combination when you have bends and turns. The rigid pipe will help you prevent kinks in the flex duct. 

2. Measure the Location 

Inch scale

How much duct and where it will go depends on the size of your HVAC system and your home’s needs. Use a tape measure to find the length and width of the space where you will install the duct. If you need help, ask a friend or family member to hold one end of the tape while you measure. 

The measurement will help you determine how much material you need to complete the job. It is a good idea to add a few extra feet to your total just in case you make a mistake during installation. You can always cut off the excess but cannot add more if you do not have enough. Also, remember to measure t where you will place the register or grille. You want a snug fit so that no air escapes around the edges. 

3. Plan Your Installation 

Before you start working on your new duct setup, take some time to plan the process. This step is critical because it helps you avoid potential problems and wasted materials. For example, if you are working in the attic, ensure you have enough light to see what you are doing. 

Also, take measurements of the longest and shortest sides of your space. That will help you determine how to cut your materials to fit the area without wasting any. Most importantly, do not forget to factor in where you will place the register or grille. You want to ensure it is in the correct spot and that the ductwork will not interfere with its operation. 

Your flex duct must run on a free and level surface. Do not try to install it over insulation or around joists and other objects. The friction will impede airflow and reduce your system efficiency. You can hang it from the joists but make sure there is a minimum of three inches between the bottom of the duct and the top of the insulation. Use hangers specifically for this purpose and attach them every four feet. 

4. Cut and Attach the Duct 

inside of a pipe

Your ductwork installation is now ready to begin. Cut the flex duct using a sharp knife or scissors. Remember to leave enough extra on each end for the connections. A pipe cutter or saw will help you when cutting the metal pipe. Ensure the cuts are square to create a tight seal when attaching the sections. 

Next, use screws and hangers to secure the flex duct to the joists or other support structures. Use sheet metal screws and washers for this purpose. Zip ties will suffice if you work with fiberglass. Remember to leave enough slack in the system so you can make all the necessary connections. 

5. Make the Connections 

Now it is time to connect the different sections of your flex duct system. It is a straightforward process as long as you have the correct tools. Start with the register or grille and work your way back. Use screws, clamps, or tape to make the connections. Make them tight to prevent air from escaping. Also, use foil tape or mastic sealant to secure the connections further and prevent leaks. 

Summary 

All HVAC systems require some ductwork to deliver the conditioned air. The most common type of duct is made from metal or fiberglass and is attached to the HVAC unit with screws or clamps. However, these traditional ducts can be difficult to work with, especially in tight spaces. Flex ducts allow you to maneuver around obstacles and are easier to install. Follow these five easy steps to complete your flex duct installation. 

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