Dulley, James. Furnace, Water Heater Need Combustion Air. Union News.
December 19, 1989.
Abstract: This newspaper article discusses combustion air for
furnaces. If a furnace is deprived of air it will not run efficiently and
can produce carbon monoxide, which can be hazardous when inhaled. Common
indicators that a furnace is not working properly include yellowish flames
and flames that burn irregularly.
An effective way to supply air to a furnace is to build an enclosure
with a duct to the outside around the furnace. A square inch of free space
is required for every 4,000 Btu/hr. if the vent is vertical. The vent will
need twice the space if it is horizontal. The outdoor duct should not run
directly to the furnace opening because the draft will cause the furnace
to malfunction. The furnace dealer can recommend specifications for the