FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL

**Definition:** This place covers:

Self-contained heaters comprising heat generating means for heating fluids:

**Limiting references (this place does not cover):** - Steam generation -> F22

**Glossary:** - Water includes other liquids;air includes other gases or gas mixtures: "water" and "air" always mean respectively, the liquid and gas to be heated - Furnace tubes: means tubes inside the heater wherein combustion is performed - Fire tubes: means tubes inside the heater wherein combustion is performed - Water tubes: means the tubes inside the heater through which water to be heated flows - Heater: means apparatus including both heat generating means and means for transferring the generated heat to water or air