What essential feature must be included on a water heater sold in Kentucky?

A water heater sold in Kentucky must include a serial number, which serves as a unique identifier for the unit. This feature is crucial for several reasons. It allows manufacturers and service technicians to track the production and history of the appliance, including warranty status, recalls, and service records. The serial number also helps ensure compliance with state and federal regulations regarding appliance performance and safety. It aids in verifying that the water heater meets specific requirements set forth by the manufacturers and regulatory bodies.

The other options, while important in their own rights, do not share the same level of regulatory necessity. Warranty information and user manuals are valuable for consumers but are not mandated by law to be displayed directly on the unit itself. Energy efficiency ratings are typically provided but may not be a requirement for all states in every scenario. Therefore, the inclusion of a serial number is an essential feature that ensures safety, traceability, and regulatory compliance for water heaters in Kentucky.