The U.S. Department of Energy (DOE) is undertaking a rulemaking to amend energy conservation standards for commercial water heaters. Once completed, this rulemaking will fulfill DOE's statutory obligation under the Energy Policy and Conservation Act, as amended, (EPCA) to either propose amended energy conservation standards for commercial water heaters and hot water supply boilers (CWHs), or determine that the existing standards do not need to be amended. (Unfired hot water storage tanks and commercial heat pump water heaters are being considered in a separate rulemaking.) DOE must determine whether national standards more stringent than those that are currently in place would result in a significant additional amount of energy savings and whether such amended national standards would be technologically feasible and economically justified. DOE proposed to amend the standards for certain classes of CWH equipment for which DOE has tentatively determined there is clear and convincing evidence to support more-stringent standards. Additionally, DOE has proposed to codify standards for electric instantaneous CWH equipment from EPCA into the Code of Federal Regulations.