Building A Plenum With Sheet Metal

Shop for sheet metal duct pipe fittings at ferguson.

Building a plenum with sheet metal.

If i am going to have a supply plenum run for approx. The sizes of the supply plenums available here fit the furnaces. Adding the velocity stacks straight to the plenum would be ideal for ease of install at this point but the volume of the plenum even with the stacks in it is still too much. Longer runners improve low and mid range torque at the expense of top.

Sheet metal plenums. But even with all duct board is it still a building cavity. 25 feet should it be ductboard or metal and is hard pipe runs preferable over flex. If it s ok with duct board what other materials can make up the walls.

The two basic methods of tuning an intake manifold are varying the length of the intake runners and the volume of the plenum. Duct board vs metal plenums supply is on perferable over the other. Simply measure and cut to size using tin snips to match the supply opening of the air handler furnace or evaporator coil. As the air blows from the furnace or air handler it flows through the supply plenum and any ductwork attached to it.

A possible construction is all fiberglass duct board with a latitce of metal studs to separate reinforce the top and bottom. Once the full plenum was welded in the plenum was tossed into the jig. Constructed of 26 gauge sheet metal the knock down design of the plenum takes up very little space and simplifies transporting to the job site. Some lite metal work needed to be done to the plenum in order to mate to the notched sections.

The trim to fit plenum fully assembled measures 20 in. Arizona 24 california 24 nevada 23 type plenum 20 plenum drop 4 gauge 26ga 24 lined yes 8 no 13 flange width 0 5 inches 20 1 5 inches 4 width 13 75 inches 6 16 75 inches 6.