### Question
Can you define what instantaneous water heater means?


### Answer
**Instantaneous water heater** is defined as the following in *42 U.S.C. § 6311*:

> a water heater that has an input rating of at least 4000 Btu per hour per gallon of stored water

#### Citation:
  - *42 U.S.C. § 6311*
  - Heading: **CHAPTER 77-ENERGY CONSERVATION > SUBCHAPTER III-IMPROVING ENERGY EFFICIENCY > Part A&ndash;1-Certain Industrial Equipment**

