I want to replace my kitchen exhaust roof cap. Is there a standard roof cap for kitchen exhausts?
My exhaust fan is integrated with an over-the-range microwave. Looks like 6 or 8-inch galvanized duct (two elbows and about 8 feet of horizontal run). There is no backdraft damper currently. I'd like a backdraft damper and a bird screen, unless those are bad ideas.
I have a roof jack right now (looks like this but a lot older):
I've seen these low profile square vents. Home Depot explicitly states that they are for kitchen duct outlets, but are they the best choice?
These are the gooseneck styles. They include a backdraft damper, but does that impede airflow?
I like this cap, but I suspect it's not intended for exhaust ducting. More likely for a gas appliance like a water heater:
The attic space above the kitchen is sealed (the kitchen is built out from the 2-story house), so I can't install a damper in the ductwork. It's got to be in the roof cap or just above the fan (or not at all). The cap has to fit over the duct pipe, and there's no way to seal the connection joint (unless I take apart the kitchen ceiling).
Anyone else faced with this choice lately?