I’m installing the range hood for our new kitchen. The hood will be mounted through an exterior wall and venting directly out the back of the unit. Its a 48″ hood with two 3-1/4 x 10″ vents. The wall is a Structural Insulated Panel (SIP) approximately 9″ thick (including interior drywall and exterior clapboard siding.
My problem: Either I shoot two rectanglar ducts through the wall with two rectangular vent caps (although I haven’t seen any lately – are they still made?), or I can buy from the hood manufacturer a fitting which discharges both vents into a single 10″ round opening. Unfortunately, the fitting is 14″ long and the round section doesn’t start until approximately 10″ from the range end, which means the vent cap may sit off the exterior wall by as much distance as required until the fitting transitions to a round duct.
I need advice on whether I go for the more complex 2 rectangular openings, or am I OK if the OEM fitting forces the vent cap to sit off the exterior wall by a few inches?
Replies
Several years ago I had a simlar situation............but the wall was only 6" thick. The transition piece was way too long and the exterior diameter put the vent into the soffit line.
Visited the local HVAC/sheetmetal shop and had them make a 6" long trapezoid box...one end sized to fit the back of the range hood and then flaring out to a double opening designed to accept two 4x10 flapper vents, side by side. And, yes 4x10 flappers are still common.
I think I paid about $40 for the custom piece. Could have made one with aluminum coil stock on the J-brake and siliconed and pop riveted same....but I was in a time crunch at the time.
........................Iron Helix