The hot water supply line in your home carries hot water from the water heater to the various sinks and baths throughout the house. In a home without recirculation, when you turn on a hot water faucet, all the water sitting in the supply lines has to pass through the pipes before hot water from the tank reaches the faucet. As a result, water may be wasted while waiting for hot water to arrive.
By running a return line from the last tap on the hot water supply line back to the water heater and installing a small circulating pump, hot water is circulated in the supply line and is immediately available when you turn on your faucet. The direction of flow moves from the water heater through the hot water supply line, through the return line, through the recirculating pump, and then back to the water heater.
A variety of systems and manufacturers are available. The descriptions below may help you select the system that makes the most sense for your specific requirements.
Types of Systems
Traditional hot water circulating systems use a circulating pump to pump hot water from the water heater, through the hot water piping, and on back to the water heater through an additional length of pipe that runs from the furthest fixture back to the water heater. This type of hot water circulating system provides nearly instant hot water at the fixtures, but wastes a tremendous amount of energy.