Full Description Standard 146 provides methods of test testing for heating capacity and energy efficiency for rating pool heaters. The standard applies to forced-circulation heaters operated by gas, oil, and/or electricity, as well as hybrid heaters.New in the 2020 edition:- Reformatted the standard as a method of test.- Expanded the scope to include heat-pump pool heaters that use earth, water, or brine as the heat source and hybrid pool heaters equipped with both a fossil-fueled burner and a heat pump.- Revised the test method to address the products included by the expanded scope.- Updated definitions and references.- Modified the specification for use of the optional recirculating loop to make clear it applies only when required by the manufacturer.- Added test methods to measure the standby and OFF-mode energy consumption.- Deleted two obsolete informative appendices have been deleted and added a new Informative Appendix B describing test conditions used by the U.S. Department of Energy to rate pool heaters.