Installing a Hot Water Recirculation System

How Recirculation Systems Work

A hot water recirculation system keeps hot water available at distant fixtures by slowly circulating water through the hot water pipes and back to the water heater. Without recirculation, water sitting in the pipes cools down between uses, and you must run the faucet until hot water from the heater reaches the fixture — wasting water and time. The typical home wastes 10,000 to 15,000 gallons of water per year waiting for hot water. Recirculation systems eliminate this waste.

Types of Systems

Full recirculation systems use a dedicated return line from the farthest fixture back to the water heater, with a pump at the water heater. These are ideal for new construction but require running an additional pipe. Comfort systems (also called crossover or demand systems) use the cold water pipe as the return line with a crossover valve at the farthest fixture — no additional piping needed, making them ideal for retrofitting existing homes. Demand systems activate with a push button or motion sensor, while timer-based systems circulate on a schedule.

Installing a Comfort System

The pump mounts on the hot water outlet of the water heater with standard threaded connections. The crossover valve installs under the farthest sink, connecting the hot and cold supply lines with a temperature-sensitive valve that opens to allow circulation when the hot water line cools below a set temperature. When hot water reaches the valve, it closes to prevent hot water from entering the cold water line. Installation typically takes 30 to 60 minutes with no pipe modifications needed.

Energy Considerations

While recirculation systems save water, they use energy to keep water hot in the pipes. Minimize energy use by choosing a demand system (runs only when you press a button) or a timer-based system programmed for peak use times (mornings and evenings). Insulate all accessible hot water pipes to reduce heat loss during circulation. Dedicated return line systems are more energy-efficient than crossover systems because they do not introduce any heat into the cold water pipes. The water savings from eliminating waste water typically offsets the modest energy cost of running the pump.