Abstract: A balancing air device for a heating unit in a building having a flue for the passage of waste combustion gases from a combustion chamber of the heating unit into a stack capable of having a draft flowing therein, comprising, a fresh outside air line connected to the combustion chamber of the heating unit for supplying air from outside the building and an air return line connected directly between the outside fresh air line and the stack for returning air supplied from outside the building to the stack when the heating unit is not operating. The cross-sectional flow areas of the outside fresh air line extending to the combustion chamber and the air return line are chosen so that, when the heating unit is not operating, the air return line satisfies a substantially constant draft flowing in the stack so that fresh outside air is not supplied to the combustion chamber when the heating unit is not operated.

Abstract: In a home heating system having a furnace with a combustion chamber for burning fuel and creating heat, and a chimney with a draft therein, an improvement comprising, an exhaust flue connected between the combustion chamber and the chimney for venting heated exhaust products from the furnace, a heat reclaimer connected into the exhaust flue between the combustion chamber and the chimney for reclaiming heat from the heated exhaust product, and an outside air line for supplying air from the outside of the house to the combustion chamber. A first flue portion of the exhaust flue is connected between the combustion chamber and the heat reclaimer, and a second insulated flue portion of the exhaust flue is connected between the heat reclaimer and the chimney. An outside air by-pass or balancing line is connected between the outside air line and the chimney for satisfying the chimney suction at flame-out.