My front room has an air brick just above the floor that vents from the inside to the outside. We used to have a back boiler and gas fire in this room but have had it removed. We have had cavity wall insulation put in a few years ago and at that time the exterior air bricks were replaced with new ones. Since then during the winter a cold draft flows into the room through this vent. There does not appear to be any baffles to restrict air flow direction. As I no longer have a gas fire can I block the internal vent?