Any modern house comes equipped with a hot and cold water plumbing system. Typically there is a water heater in the plumbing system to heat the water, which is delivered to your faucets and showers by pipes throughout the house. However, when the hot water is not used for a period of time, the once hot water that remains stagnant in the pipes eventually cools to the surrounding ambient temperature. This is why hot water usually has to be run the cooled water out of the pipes before you actually get hot water. This water is typically wasted down the drain-wasting up to 17,000 gallons of fresh water each year for the average household.
Hot water recirculation systems are designed to eliminate the wait for hot water and conserve that wasted water (which would normally be ran down the drain). Hot water recirculation systems keep a constant supply of hot water in the pipes, circulating the water back to the water heater for reheating. This allows the consumer to have instant hot water whenever it is needed without the wait or waste.
Hot water recirculation systems can use either a dedicated return line (a separate and “dedicated” pipe to bring the cooled hot water back to the water heater for reheating) or they can use your exiting cold water line to return the cooled water back to your water heater for reheating (a much simpler method, especially in an exiting house). Either type of return will provide faster hot water.