How to Connect a Duct to a Roof Cooler

Locate a position for cooler that will not involve having to cut a roof joist to set the cooler in place. Examine the roof from inside the attic and pick a location between two roof joists. Put a 10d nail through the roof in the center of the space between the joists to mark the center of the hole that you can cut in the roof for the cooler.

Set an extension ladder against the side of the house to reach the roof. Locate the nail extending through the roof’s surface. Remove any roofing tiles or shingles from the area to access the roof sheathing material. Use a string compass with a pencil to draw a hole on the roof that is the same diameter as the collar of the roof cooler. Drill a hole through the roof with a 12-inch drill bit along the inside edge of the drawn circle. Lower a jig saw blade through the hole and then cut through the roof along the drawn line. Remove the cut piece of roofing.

Put the bottom flange of the cooler on the roof’s surface. Nail the flange into place with 10d nails and a hammer. Put the top half of the flange on the bottom half. Loosely screw the hinges to the top and bottom halves of the flange, putting a hinge over each of the four flange edges. Set a carpenter’s level on top of the combined flanges. Adjust the top half of the flange with adjustable hinges holding the top half to the bottom half of the flange on the sides, to level the flange against the slant of the roof.

Pivot the top half of the flange by pressing downward on the hinges or raising the hinges upwards over the bottom half in all directions to level the top out. The hinges are stiff enough to hold their shape after adjustment but flexible enough to bow outward or straighten in the center to allow for slight movement of the top flange over the bottom. Tighten the screw connecting the hinges to the top and bottom flanges to hold the top half level. Replace the roof tile and shingles covering the adjoining area and overlapping the flange. Cut the tile or shingles using a wet saw for tiles and a utility knife for the shingles to fit them back in place.

Set the barometric damper from the cooler kit into the cooler, aligning the position of the damper according to the markings set on the flange. The damper regulates the amount of air drawn into the system. Hook the small front cover plate over the small hooked ledge running along the front of the top flange. Screw the plate into place with the included screws. Repeat the process with the large front cover plate and the bottom flange.

Seal all the flange joints with a bead of roofing sealant. Put roofing sealant over the nails holding the flange to the rooftop to avoid leakage.

Go back to the attic. Bend alternating tabs around the top of the duct collar connected to the flexible ducting outward at a 90-degree angle. Put the still straight collar tabs through the circular hole in the square duct apron piece so that the bent tabs are flush with the apron rear. Bend the still straight tabs 90 degrees outward on the other side of the apron piece so that the collar is held in place between two rows of bent collar tabs.

Put the apron against the roof with the collar centered on the hole cut through the roof. Nail the apron in place with the 10d nails and the hammer.

Run the flexible ducting to the nearest rectangular main heating duct. Wrap a strip of duct strapping around the body of the duct every 5 feet and then screw the strapping to a joist in the ceiling or floor with a wood screw and Phillips-head screwdriver. Put the duct collar on the side of the main duct and trace the outside onto the duct with a grease pencil.

Set a flathead screwdriver against the side of the duct on the inside line of the traced circle and hit the screwdriver with a hammer to break through the duct side. Cut the traced hole in the duct with sheet metal shears and remove the cut piece.

Press alternating tabs on the collar outward, and then slip the straight tabs into the duct hole. Reach into the duct and press those tabs outward to hole the collar in place. Slip the end of the flexible ducting over the end of the collar. Put a strip of duct tape across the joint to hold the duct to the collar.