A home heating furnace is a type of combustion furnace. Gas piped into a combustion chamber mixes with air drawn in from around the furnace. This gas-air mixture burns. A blower draws in a separate stream of cool air and pushes it around the chamber. Heat from the chamber warms this air before it travels to the rooms. A typical furnace has four combustion chambers.
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World Book diagram by Arthur Grebetz</P>
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