How to Install Square Ducts for Ventilation

Circular ducts can be used when square ducts do not fit.

Square ducts, better known as rectangular ducts, are installed to supply conditioned air to a room or to vent air out of a home. Connecting square ducts is a delicate process, as the ducts must be tightly sealed to each other to prevent air from escaping from the vent. Once you have the proper supplies and directions, you can connect and install square ducts together, creating a perfect seal between each duct quickly and efficiently.

Things You'll Need

• Starting collar
• Tape measure
• Marker
• Metal cutting snips
• S-cleat connectors
• Duct straps
• Wooden screws
• Drill
• Pliers

Instructions

1. Install the starting collar from the system you want to ventilate. Push the starting collar into place and secure it by twisting the metal teeth with your hands. Read the manual of the system you wish to ventilate for directions on how to properly attach the starting collar.

2. Measure the size the square ducts must be cut to with the tape measure. Mark the ducts with the marker to the size they must be cut to. Cut the ducts using the metal cutting snips.

3. Attach an S-cleat connector to the end of the starting collar. Push in the S-cleat to the end of the starting collar and bend over the metal teeth to secure it to the starting collar.

4. Push the square duct into the starting collar with the S-cleat connector. Bend the teeth on the S-cleat connector to secure the square duct to the starting collar.

5. Install a duct strap every 12 inches. Wrap the duct straps around the installed ducts and secure them with wood screws to the wood trusses using the drill.

6. Attach the remaining square duct pieces together. Attach an S-cleat connector to each end of the square duct by bending the teeth to hold it to the duct. Push in the next piece of duct into the S-cleat and bend the teeth to hold it in place.

7. Turn on the air system and check for any air leaks at any of the connections. If you notice any air leaks, make sure all the teeth of the S-cleat are properly bent.

Tips & Warnings

• If you do not have the strength to bend the metal teeth with your hands, use a pair of pliers to bend the teeth.

References

• Alpine Home Air Products: Ductwork
• HVAC-For-Beginners.com: Air Duct Installation