Colmac heat pumps offer commercial and industrial users of sanitary hot water, an energy-efficient means of heating water to temperatures as high as 176°F (80°C). The Colmac heat pump water heater uses the same operating principle as an air-conditioner or domestic refrigerator. The heat pump gathers heat from the surrounding air or water, and through the refrigeration cycle, deposits the heat into the water at a usable temperature. This principle of moving heat with a heat pump, rather than generating it by burning fossil fuel (i.e. natural gas), or electric resistance, makes water heating with heat pumps the best choice for conserving energy. Depending on the temperature of the air or water supplied to the heat pump, water can be heated using one-third to one-fourth of the energy required by electric resistance, or gas.