Water heating

Water heating is a thermodynamic process using an energy source to heat water above its initial temperature. Typical domestic uses of hot water are for cooking, cleaning and bathing, and space heating. In industry both hot water and water heated to steam have many uses.

Three propane water heaters.

The most common energy sources for heating water are fossil fuels: natural gas, liquefied petroleum gas, oil or sometimes solid fuels (coal or firewood. These fuels may be consumed directly or by the use of electricity (which may derive from any of the above fuels or from nuclear or renewable sources). Alternative energy such as solar energy, heat pumps, hot water heat recycling, and sometimes geothermal power, may also be used as available, usually in combination with gas, oil or electricity.

Solar water heaters

Direct-gain solar heater panels with integral storage tank installed near a house in the Cirque de Mafate in Réunion

Solar collectors for solar powered water heaters are installed outside dwellings, typically on the roof or nearby. Nearly all models are the direct-gain type. They consist of flat panels in which water circulates.

Geothermal heating

In countries like Iceland and New Zealand, and other volcanic regions, water heating may be done using geothermal power, rather than combustion.

Other websites

• How It Works - Water Heater Archived 2006-11-23 at the Wayback Machine
• PATH Tech Inventory: Solar Water Heaters Archived 2015-03-30 at the Wayback Machine
• Tankless Water Heaters are Brutal on the Grid When Popularized Archived 2007-05-10 at the Wayback Machine
• Stiebel Eltron Tankless Water Heaters
• Water Heating for Dairies in NZ
• U.S. Department of Energy Water Heating Guidance
• Advantage and Disadvatage water heater