(518) 746 -0182
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22 Hudson Falls Road, Door 3
South Glens Falls, NY

Supply Air Plenum

We Fabricate Supply Air Plenums to Your Custom Sizing

Supply Air Plenum

Major forced air furnace brands come in many different sizes, making the measurements for the supply air plenum less than universal.

Our shop is equipped to fabricate supply air plenums to the custom size of your hot air furnace or air handler. Making it easy for you or your heating and cooling professional to install the new system properly.

What is a supply air plenum?

Supply air plenums are sheet metal boxes fabricated to fit the top of your forced air furnace or air handler. The plenum is a chamber, collecting the air blown from the blower of the furnace and then distributed through the duct work running to each room of the home.

All of our supply air plenums are fabricated with 26 gauge galvanized sheet metal, in (2) L-shape sides and assembled by hammering together Pittsburgh joints. Every plenum is formed with a 1/2″ plenum bend on the bottom end and plenum cap on top, unless no flange is noted by the customer.


width (W) of furnace supply opening X depth (D) of furnace supply opening X desired height (H) of plenum



Product Details:

  • Fabricated with 26 gauge galvanized sheet metal
  • (2) L-shape sides
  • Pittsburgh joints
  • 1/2″ plenum bend ( unless noted otherwise )
  • Plenum cap

Common Sizes: We fabricate all supply air plenums to each customers needs. Here are a few examples of common supply air plenum sizes (in inches):

  • 20 wide x 20 deep x 36 Tall
  • 20 x 20 x 48
  • 16 x 20 x 36
  • 16 x 20 x 48
  • All custom sizes are available. We have 48″ x 96″ and 36″ x 96″ flat galvanized sheet metal to fabricate with. Please make note of your exact measurements before ordering.

Please visit our contact page to send us any questions on supply air plenum sizing and fabrication.


You can purchase sheet metal hand tools used in the fabrication process from our Amazon.com Tool Shop

Full disclosure: we are Amazon.com affiliates