How To Insulate Sheet Metal Plenum

Plenum should be dry before external insulation is applied.

How to insulate sheet metal plenum.

Press a continuous strip of foil tape to all longitudinal seams along straight runs of duct. 38 to 102mm insulation boards fibrous glass insulation boards are also available for application to the outside of sealed sheet metal ducts housings and plenums. You can fasten and secure the ends of the batts with duct tape but that may cause the insulation to get spoiled. Do not use rigid foam insulation unless you know what the temperature rating is.

Ductwork is typically insulated with foil or vinyl backed fiberglass insulation specially made for the application. Insulation used to externally insulate hvac ducts. Duct wrap fiberglass insulation all seams need to be sealed to keep moisture out otherwise sweating may occur between wrap and sheet metal causing insulation to be damaged. Sheet metal ducts must first be tightly sealed resilient fibrous glass insulation thicknesses from 11 2 to 4 in.

Check the speed of the blower motor on the furnace. If necessary switch the wires to reduce the blower to its lowest speed. If you do insulate the plenum the irc does require you to use a vapor barrier on the exterior of the insulation or use duct insulation blankets with integral vapor barrier and tape the seam s. Use foil faced insulation batts to wrap up the pipes but see to it that the whole thing is properly covered and any previous layers are thoroughly overlapped.