While hot water heaters and hot water boilers both heat water, a hot water heater elevates the temperature of water to 125 degrees and a boiler heats it to boiling, converting water to steam. Boilers are considered superior because they serve as a water heater and heating system in one.
A conventional water heater is essentially a storage tank containing heating elements. It generates heat by using electricity or gas power, warming water to 125 degrees and maintaining the temperature through a thermostat. When the water us needed in a shower, dishwasher or other appliance, it is siphoned from the top of the tank and piped to its destination. At the same time, new, cold water is added to the bottom of the tank, where it is heated for future use.
Boilers convert water to steam, which is used for a variety of purposes, including heating air within a forced air heating system, heating water for household uses or even steam-cleaning carpets and furniture. Considered safe, boilers are also relatively inexpensive to use, thanks to their closed loop system. They are capable of operating on green power, such as burning corn pellets or firewood. In fact, those who finance their purchase of boilers say the savings in energy costs offsets interest paid.