### Question
How does the law define thermal efficiency of pool heaters?


### Answer
Under *42 U.S.C. § 6291*, **thermal efficiency of pool heaters** is defined as:

> a measure of the heat in the water delivered at the heater outlet divided by the heat input of the pool heater as measured under test conditions specified in section 2.8.1 of the American National Standard for Gas Fired Pool Heaters, Z21.56–1986, or as may be prescribed by the Secretary

#### Citation:
  - *42 U.S.C. § 6291*
  - Heading: **CHAPTER 77-ENERGY CONSERVATION > SUBCHAPTER III-IMPROVING ENERGY EFFICIENCY > Part A-Energy Conservation Program for Consumer Products Other Than Automobiles**

