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.
Where to Get On-Demand Hot Water System
On demand hot water systems offer a solution to the problem of turning on a faucet or shower and waiting for hot water. Instead of relying on pressure in the line, a recirculating pump brings hot water quickly to the faucet when it’s needed. The pump is installed between the hot and cold water lines at the faucet furthest from the water heater. It’s activated by push buttons connected with low-voltage wire or via a wireless remote control.
Once activated, the pump rapidly pulls hot water from the water heater down the hot water line. At the same time, it pushes the cold water back through the cold water line to the water heater. The pump comes on only when it’s needed. Once hot water has filled the line, the system shuts off.
A variety of products are available, but as a specialty item you may not find these systems in builders hardware stores. A web search using “on demand hot water system” or “recirculating hot water system” should provide a list of manufacturers and products.
Incentives or Rebates
Some water providers, cities, and electric utility companies may offer financial incentives for installing an on demand hot water system. Such incentive programs are uncommon so check with your water and electric utility for information on programs in your area.