New DOE Minimum
Efficiency Standards

The Department of Energy (DOE) sets national minimum energy efficiency standards for commercial and consumer (residential) water heaters.

All water heater manufacturers will be required to meet new minimum efficiency standards for both commercial applications by October 2026 and residential applications by May 2029.

A. O. Smith is committed to leading our industry in compliance.

2026 Commercial Water Heater Regulatory Requirements

The Department of Energy’s (DOE) new minimum efficiency standards for commercial water heaters will go into effect on October 6, 2026. These new regulations are part of DOE’s efforts to reduce overall energy consumption in the United States. These changes will present new complexities, but A. O. Smith is prepared for the transition.

The new standards will require that only high-efficiency (condensing) gas commercial water heaters can be manufactured or imported into the United States on and after October 6, 2026.

Gas Storage Standard

Minimum Thermal Efficiency (TE) from 80% to 95%

Gas Instantaneous Standard

Minimum TE from 80% to 96%

Gas Residential-Duty Storage Standard

Uniform Energy Factor (UEF) of 0.9297

View Ruling

2029 Residential Water Heater Regulatory Requirements

The Department of Energy’s (DOE) new energy conservation standards for residential water heaters will go into effect on May 6, 2029. These new regulations are part of DOE’s efforts to reduce overall energy consumption in the United States.

The standards will require minor updates to gas-fired storage water heaters. Electric storage water heaters >35 gallons will require heat pump technology. The gas instantaneous (gas tankless) product category has been excluded from this rule and will be addressed by the DOE in a subsequent rulemaking.

The new energy efficiency levels will be required for all residential water heaters produced on and after May 6, 2029.

Gas-fired Storage

<20 gallon: new standard to add UEF to these models – no current A. O. Smith products impacted
≥20 and ≤55 gallon: incremental UEF increase – atmospheric gas units will require the addition of a damper
>55 and ≤100 gallon: no change
>100 gallon: new standard to add UEF to these models

Gas-fired Instantaneous

No change at this time

Electric Storage

<20 gallon: new standard to add UEF to these models – compact units <20 gallon will have a UEF and FHR value added by the implementation date
≥20 and ≤35 gallon: no UEF change but will be limited to a max FHR of 50 gallons and a max temperature setting of 135°F o All nominal 40 gallon electrics are currently rated at 36 or 37 gallons and will have to be reduced to 35 gallons
>35 and ≤120 gallon: requires Heat Pump Water Heater
>75 gallon grid-enabled: no change
>120 gallon: new standard to add UEF to these models – no current A. O. Smith products impacted

Electric Instantaneous

<2 gallon: no change
≥2 gallon: new standard to add UEF to these models – no current A. O. Smith products impacted

View Ruling

Still Have Questions?

Why are the regulations changing for consumer (residential) water heaters?

The Energy Policy and Conservation Act, as amended (“EPCA”), prescribes energy conservation standards for various consumer products and certain commercial and industrial equipment, including consumer water heaters. EPCA also requires the U.S. Department of Energy (“DOE” or “the Department”) to periodically determine whether more stringent standards would be technologically feasible and economically justified, and would result in significant energy savings.

In this final rule, DOE is adopting amended energy conservation standards for consumer water heaters. It has determined that the new and amended energy conservation standards for these products would result in significant conservation of energy, and are technologically feasible and economically justified.

Source regulations.gov

Why are the regulations changing for commercial water heaters?

The Energy Policy and Conservation Act, as amended (‘‘EPCA’’), prescribes energy conservation standards for various consumer products and certain commercial and industrial equipment, including Commercial Water Heating (‘‘CWH’’) equipment. EPCA also requires the U.S. Department of Energy (‘‘DOE’’) to periodically review standards. In this final rule, DOE is adopting amended energy conservation standards for CWH equipment.