Those of you with footbox vents; Do have open/close gates to close the fresh air coming in? If so how often do you close it? For the guys without a gate, do you wish you had one?

I’m planning on putting a 3 inch vent into the footbox and just to keep it simple, i wasnt going to put a gate valve. It will have an electric Atwood brand bilge blower. The footbox will be surrounded by heat insulation. Just seeing what guys thoughts are. I appreciate your input.