Abstract: An air flow modulating device comprising a flapper, a mount and a conduit. The conduit may be T-shaped and may be attached to an intake conduit of a sealed combustion condensing appliance, or other appliance having an air intake conduit, through a first portion of T-shaped conduit. The mount may be connected to a second portion of T-shaped conduit and the flapper may rotate between an open position and a closed position about an axle of the mount. The device operates to allow for a sealed combustion condensing appliance to immediately intake interior air when an exterior air source is obstructed, limited or reduced, or in response to changes in air pressure due to uncontrollable natural forces.

Abstract: An air flow modulating device comprising a flapper, a mount and a conduit. The conduit may be T-shaped and may be attached to an intake conduit of a sealed combustion condensing appliance, or other appliance having an air intake conduit, through a first portion of T-shaped conduit. The mount may be connected to a second portion of T-shaped conduit and the flapper may rotate between an open position and a closed position about an axle of the mount. The device operates to allow for a sealed combustion condensing appliance to immediately intake interior air when an exterior air source is obstructed, limited or reduced, or in response to changes in air pressure due to uncontrollable natural forces.