A.O. Smith (AOS) has issued a recall of several models and brands of water heaters that pose a fire hazard. Consumers that have purchased the affected water heaters can receive a free repair from the company to alleviate the issue.

The recall affects 30, 40, and 50-gallon natural gas or propane gas-fired Ultra-Low NOx emission gas water heaters. These water heaters were designed to comply with air quality standards in California and were primarily sold throughout the state.

A.O. Smith is recalling the American, A. O. Smith, Kenmore, Reliance, State, U.S. Craftsmaster, and Whirlpool brands of water heaters that were manufactured from Apr. 8, 2011, through Aug. 1, 2016. The water heats affected by the recall have a four-digit serial number between 1115 and 1631. The serial number represents the year and week that the unit was produced.

The serial number, model number, and brand name are located on the data plate on the water heater next to the gas control valve/thermostat. The brand name is printed near the top of the unit. To check if a water heater is affected by the recall, consumers can visit here, where they will be instructed to input their model number and serial number.

The recalled water heaters were sold by independent contractors, plumbers, and plumbing supply vendors in addition to a range of home improvement and hardware stores primarily in California. The water heaters were sold from April 2011 to December 2016. The units retailed for $500 to $1000 and were manufactured in the U.S. and Mexico.

According to A.O. Smith, six fires have been reported from the installation of the water heaters directly on a combustible surface. The company has not received any reports of injury from the units.

A.O. Smith is urging consumers that have the affected water heaters installed in their home to turn off the units and stop using them immediately. Consumers should contact A.O. Smith to determine if their unit requires a free repair.

Consumers that purchased the recalled water heaters under the Whirlpool, U.S. Craftmaster or American Water Heater brands can call 1-866-854-2793 from 8 a.m. to 10 p.m. EST, Monday through Friday and 9 a.m. to 6 p.m. Saturday and Sunday.

Purchasers of the recalled Reliance, State, A. O. Smith, and Kenmore branded water heaters can call 1-866-880-4661 from 8 a.m. to 8 p.m. EST, Monday through Friday and 9 a.m. to 6 p.m. on Saturday. More information will be provided on the repair of the water heaters during these calls.

As of this morning, A.O. Smith stock was up .45 percent to 45.43.

Water Heater A.O. Smith has recalled several models and brands of water heaters due to a fire risk. Consumers can receive a free repair of the affected water heaters from the company. A woman walks past a window display of a natural gas water heater at a Peoples Energy payment center July 11, 2003 in Chicago, Illinois. Photo: Getty Images/Tim Boyle