Commercial water heaters include a wide range of equipment that heats potable water for purposes other than space heating. Businesses with commercial water heaters range from office buildings, which typically use very little hot water, to restaurants, which may use large volumes. Although there are electric and oil-fired commercial water heaters, gas-fired equipment accounts for most of the energy consumption of this product category.
Congress established the first national standards for commercial water heaters as part of the Energy Policy Act of 1992. Those standards were equivalent to the efficiency levels in ASHRAE 90.1-1989. ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers) 90.1 is a commercial building energy code. The Energy Policy and Conservation Act (EPCA) requires that if the equipment efficiency levels in ASHRAE Standard 90.1 are amended, DOE must either establish amended standards for the products at the levels specified in ASHRAE 90.1 or establish more stringent standards if they would result in significant additional energy savings and are technologically feasible and economically justified. DOE adopted amended standards for commercial water heaters in 2001 based on the efficiency levels in ASHRAE 90.1-1999. The standards include maximum standby loss requirements and minimum thermal efficiency levels. The standards took effect in 2003.
In 2015, DOE published a final rule amending the standards for commercial oil-fired storage water heaters to reflect the efficiency levels in ASHRAE 90.1-2013. The thermal efficiency levels were raised to 80%, matching the current standards for commercial gas-fired storage water heaters, and took effect in October 2015.
Technology options for improving efficiency include the use of condensing technology for gas-fired water heaters and improved insulation for tanks on all storage models.