A 86,000 BTU furnace & 39,000 BTU water heater are being installed in new home. Both units will have vertical round ducts to provide combustion air & both ducts will terminate in attic space. Holes have been cut in wall sheeting to allow for required ope nings centered near gables that will provide combustion air. Siding contractor started his portion of job & panels he`s using for attic venting have 1/2″ wide slots by 4″ long. How many slots are required on both ends of attic space to provide required

A 86,000 BTU furnace & 39,000 BTU water heater are being installed in new home. Both units will have vertical round ducts to provide combustion air & both ducts will terminate in attic space. Holes have been cut in wall sheeting to allow for required ope nings centered near gables that will provide combustion air. Siding contractor started his portion of job & panels he`s using for attic venting have 1/2″ wide slots by 4″ long. How many slots are required on both ends of attic space to provide required