Water Heater Rating Improvement Act of 2009

Water Heater Rating Improvement Act of 2009 - Amends the Energy Policy and Conservation Act to require the Secretary of Energy to publish a rule that establishes a uniform efficiency descriptor and accompanying test methods for water heaters, storage water heaters, instantaneous water heaters, and unfired water storage tanks (covered heaters). Requires: (1) the efficiency descriptor and accompanying test method to apply to all water heating technologies in use and to future water heating technologies; and (2) the efficiency descriptor to be the efficiency standard for covered heaters.

Sets forth provisions concerning a mathematical conversion factor for converting the measurement of efficiency for covered heaters from the test procedures in effect on the date of enactment of this Act to the new energy descriptor.

Authorizes the rule to exclude a specific category of covered water heaters from the uniform efficiency descriptor if the category of water heaters: (1) does not have a residential use and can be clearly described; and (2) are rated effectively using the thermal efficiency and standby loss descriptors applied to the category.

Requires the Secretary, in establishing the rule, to contract with the National Institute of Standards and Technology to conduct testing and simulation of alternative descriptors identified for consideration.

Considers a covered water heater to be in compliance with the rule and with any revised labeling requirements established by the Federal Trade Commission (FTC) to implement the rule if the covered water heater: (1) was manufactured prior to the effective date of the rule; and (2) complied with the efficiency standards and labeling requirements in effect prior to the rule.