A.O. Smith Water Products Co., of Ashland City, Tenn voluntarily recalled about 1,500 Natural and Propane Gas Water Heaters because the water heater's flue gas temperatures can exceed safe limits and produce excessive te mperatures in the venting unit, posing a fire hazard. Also, the water heater's exhaust can leak into the surrounding room, posing a carbon monoxide hazard. This recall involves certain 75 gallon natural and propane gas water heaters. "A.O. Smith" or "State" is printed on the side of the unit. These products were sold by independent contractors and plumbers nationwide from November 2007 through January 2008 for between $1,000 and $2,500.