We had patched the two existing roof vents in the old attic when we insulated the roof. But then I decided to use one for the ERV exhaust.
The Chosen Roof Vent
I opened the vent by cutting the metal front corners and bending it back. I had to cut through the roof patch and remove a section for the ductwork.
Cutting through the plywood patch
Fitting the butterfly vent and the ductwork into the existing collar was no picnic. The vent collar which was 8″ instead of 6″ so I had to buy a new butterfly vent too. I tried a longer piece of pipe to go through the ceiling but I could not get it at the right angle. I decided to just attach the flex duct to the butterfly vent piece but the new vent would not go all the way into the collar even though it was the right size. It was something about the angle but I couldn’t figure out how to fix it. I was able to screw the vent to the collar on two sides and it appeared sturdy enough. Then I replaced the screen top on the vent and screwed the vent cover closed again. I taped over the seams that I made on the upper side.
From inside the flex duct goes through the ceiling to the butterfly vent at the top of the shaft.
Ductwork through the roof
And the three large flexible ducts are intertwined a bit to hold them up off the lid of the ERV. There is the supply in, the exhaust out and the exhaust from the bathroom duct. The rest of the ductwork is shorter on the other side of the ERV.
Interior Supply and Exhaust Side of ERV
It is just possible to make out the upper and lower ductwork on this side of the ERV. The upper pipes are exhaust in and the lower pipes feed the supply lines. It is a tight arrangement with all the ductwork in this small central spot and I hope it passes inspection!