How Water Heaters Function
A water heater is used to supply a residence with the hot water needed to complete daily tasks, such as laundry, bathing and dish washing. A water heater is generally a large metal tank that is connected to a water line and a gas or electric power source. The heater has heating elements located near the bottom of the tank. These heating elements warm the water in the tank. As the water heats, the hot water rises to the top of the tank while the cooler water stays near the bottom. The water is pumped out of the tank from the top and transported throughout the home by pipes.
Why Fast Recovery?
Normal water heaters have only enough heating elements to heat one tank of water at a time. If, for example, someone takes a long shower or runs the dishwasher and the clothes washer at the same time, the water heater will be drained of hot water fairly quickly. Normal water heaters need to refill and heat the cool water before more hot water will be available; this process can take up to 30 minutes in an average water heater. Fast recovery heaters speed up the process by heating the water in smaller batches. This allows hot water to be available over a more continuous length of time.
How Fast Recovery Heats
Fast recovery water heaters have two heating mechanisms. The main mechanism, located in the bottom of the tank, takes care of heating the bulk of the water when the tank isn't being used. However, a second heating element located closer to the top of the tank steps in when the tank is being drained. This heating mechanism quickly warms up small portions of water near the top of the tank, which allows the bottom mechanism time to recover the drained system.