Insulating Metal Ductwork In Attic

Ted also has inherited a powered attic ventilator.

Insulating metal ductwork in attic. Close to 25 of the energy you use to heat and cool your home disappears through leaky ductwork. Sometimes metal ducts are lined with duct liner a 1 inch thick fiberglass board that insulates the interior of the duct rather than the exterior. Effect of inadequate insulation on ductwork. Duct liner isn t generally a diy installation and if your ducts already have liner you don t need to insulate the exterior.

The effective r value of a buried duct installation depends on the size of the ducts the r value of the duct insulation and the depth of the loose fill insulation. The department of energy claims that the average us home loses hundreds of dollars a year in heating and cooling costs. Loose fill or batt the common term for blanket insulation. But our erv ducts stand alone system not tied in w heat pump and 2 jumper ducts for pressure balancing from bedrooms are suspended above the insulation in our vented attic.

When insulating hvac ductwork use a foil faced fiberglass insulation with an r 6 or higher r value. Wrap the insulation around the duct and then pinch the seam closed. Gaps of inch or less can be sealed with fire blocking caulk 3m fire block sealant. Sometimes the insulation is inside the ductwork.

The existing metal ductwork in an older home may or may not have insulation. Repeat to insulate the remaining ducts. This is because metal is very good at transferring heat and also why it is a horrible insulator. Insulation works because it is very inefficient at transferring heat.

Youtube insulating attic ductwork. Metal flashing or scrap plywood to create a safety gap of at least 3 inches all around fixtures. Apply a long strip of foil tape along the seam in the insulation. To install preformed duct insulation start by disconnecting an elbow to expose the end of the duct.

Other times insulation may be on the outside. Proper duct insulation is a major key to ensuring your home s energy efficiency. Use the type of metallic foil duct tape recommended by the insulation manufacturer to seal and hold the insulation in place. The 1 800 square foot brick ranch in climate zone 4 dates from the 1960s but the previous owner installed both a furnace and ductwork in the attic just four years ago.

Secure the insulation with short strips of foil tape. Think about it if you touch the metal side of a frying pan on the stove you get burned right. Our heating and ac ducts are 100 within the thermal envelope in the floor trusses above our insulated basement. Wires exhaust fans and ducts.

Table 1 shows effective r values for 8 inch round ducts at three attic insulation levels and three duct insulation levels r 4 2 r 6 and r 8.