We recently installed a kitchen range hood, 10" round duct and a Fantech RE(C) external blower (mounted on curb on side of house). No one mentioned and we never considered that we'd have backdraft or bugs or anything else. But with summer temps, we have hot air coming in and are afraid this winter we'll have cold air.

We'd like to have a backdraft damper installed. How easy will this be now that the system is already in?