The life of a gas water heater will vary depending on care and maintenance of the unit and factors like mineral content of the water. On average, most water heaters will need to be replaced after 10 to 12 years.

The two main factors that should be considered when replacing a water heater are initial cost and operating costs (which are a function of the water heater’s efficiency). High-efficiency gas water heaters have several features that reduce the cost of heating water.

• The tank walls have higher levels of foam insulation, as high as R-13.
• Instead of using a standing pilot light, some high-efficiency models use an intermittent ignition to light the burner.
• The heat exchanger efficiencies are improved, allowing heat from the gas burner to more efficiently and completely heat the water in the tank.
• Some models feature "sealed combustion" burners and power venting for even greater efficiency.

What To Look For

The Gas Appliance Manufacturers Association (GAMA) sponsors an efficiency certification program. This program verifies manufacturers’ equipment efficiency ratings according to a standard test method. Efficiencies of water heaters are expressed by a number called an Energy Factor. Gas water heaters with an Energy Factor of .60 or greater are considered high-efficiency models. A Consumer's Directory is published biannually which lists the manufacturer's model numbers and Energy Factors. The Federal Trade Commission (FTC) requires that all storage type water heaters be labeled with an "EnergyGuide" label, which is based on the GAMA certification. This label shows, based on the national average cost of fuel, the estimated annual operating cost for that particular water heater. The label also shows how that particular water heater compares with other comparable models.

All water heaters should be installed according to the manufacturer's specifications.