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Types of Water Heaters – A Thomas Buying Guide


Water Heaters are systems that are intended to heat water to regulated temperatures for a variety of purposes. Familiar domestic uses of these systems include the heating of water to assist in washing clothes or dishes and taking showers or baths. Additional domestic uses of water heaters can be to heat the water in swimming pools and spas. In the typical water heater, the water is heated within the unit and is then circulated to the desired point of use or application by way of a series of pipes, pumps, and valves.

Three ways of characterizing water heaters are by their design, their fuel source, and by their intended application. Collectively, these methods lead to the following list of types of water heaters:

Types by design

    • Traditional tank water heaters
    • Tankless (or on-demand) water heaters
    • Indirect fired water heaters
    • Heat pump style water heaters
    • Condensing water heaters

    • Types by fuel source
    • Gas fired water heaters
    • Electric water heaters
    • Oil fired water heaters
    • Solar water heaters
  • Types by application
    • Booster water heaters
    • In-line water heaters
    • Feed water heaters
    • Instantaneous hot water heaters
    • Swimming pool water heaters
Note that the water heaters summarized in this article are mostly focused around the heating of potable water. There are other styles of heaters that can perform the function of heating water in process applications. For more information on other styles of heaters, review our Thomas guide on Types of Heaters.