allowing 1" to bend over the bottom of the duct. Grab your drill, drive in a 1/4" self-tapping screw. Mount another one for the other side of the duct.
Before each duct installation, trimming the inside edges of a drive can help when getting ready to hang a section of duct (see diagram below).
Prepare the Supply Air Plenum
Most duct installations start at the air handler/furnace. First determine which side, or bottom, that the return drop will be brought in to. If the return is to come in through the bottom, attach the base to the AH and raise the unit up into place. If the return is to attach to one of the sides, now is a good time to cut out the return opening in the side of the blower compartment.
Next install the air conditioner evaporator coil on top of the unit.
If your system is AC only with an air handler, the AH is probably equipped with a built in coil.
Now you are ready to prepare the supply plenum.
The supply plenum should be long enough to end 1" below the ceiling. Position the flared take-off cutouts to start the ductwork at 1" below the ceiling, as well.
There are 3 basic attachment methods for take-offs and atarters. Discuss these methods with your fabricator. You will need to know how much metal to remove as you prepare for the attachment.
The three types are the Inside hammer lock, Outside hammer lock, or the flange method. (See the illustrations below)
Prepare the ductwork and duct fittings for installation
Every section of ductwork and every fitting in the system will need some preparation before it can be hung. This usually entails bending the drive flanges and sliding on S-cletes.
Use the 3/8" side of the barfold to bend drive flanges. Keep the bends tight, and finish off by clamping down a bit with your hand seamers. But be careful to not smash down the drive flange completely.
Next, one end of each section of duct or fitting will need S-cletes fitted to the longer sides. Cut the cletes about 1/2" shorter than the duct width and slide on the two raw edges.
Related Ductwork Pages
Residential Ductwork System Drawings
Typical Trunk and Branch Duct Systems
Plenums and Return Air Drops
Rectangular Ells, Tees, and Reducers
Side Take-offs and Vertical Ells
Multiple Fittings and their Effect on the Duct System
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