Tankless Water Heaters

A conventional, storage-type water heater has an insulated tank and a relatively small gas burner or electric heating element (often two elements) to heat the water. Water is heated slowly and remains “thermally stratified” so that water drawn off from the top remains hot even after 90% of the hot water is used up. There is the risk of running out of hot water, however, because the rate of heating may not keep up with the hot water draw from typical uses, such as showers.

Tankless water heaters—often called demand or instantaneous water heaters—heat water as it is used. The main advantage is that hot water doesn’t sit in a tank all the time, losing energy through the tank walls, which occurs even with insulation.