Tankless Heater Operation
A tankless electric water heater heats household water as it is needed. When a hot water tap is activated, the system uses coils to heat the pipes over which the water travels to get to the spigot, dishwasher or washing machine.
Standard tank water heaters powered by electricity heat the water ahead of time and store it in large tanks. The tanks vary in size depending on the needs of the occupants.
Tankless electric water heaters that serve single or double occupant residences require much less space than traditional tanks. Larger models that provide hot water for large families are larger but still do not normally require the space needed to house traditional tank heaters.
Tankless Costs & Maintenance
Although tankless electric systems are around three times as expensive as tank types, they require considerably less energy to operate, which results in significant long-term cost savings. Depending on the brand, parts and qualified maintenance personnel may be difficult to find.
Home Energy: Water Heaters and Energy Conservation- Choices, Choices! [ http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/96/960510.html#side1]
Consumer Energy Center: Water Heaters [ http://www.consumerenergycenter.org/home/appliances/waterheaters.html]