Ventilation via other rooms or spaces

If a combustion appliance is room-sealed but takes its combustion air from another space in the building, or if a flue has a permanent opening to another space in the building, that space should have ventilation openings directly to the outside air. Where a flued appliance is supplied with combustion air through an air vent(s) that opens into an adjoining room or space, the adjoining room or space should have air vent openings of at least the same size directly to the outside air. An air vent(s) for a flueless appliance should always open directly to the outside air.