Are you familiar with this scenario? You get up in the morning, go to the shower or sink, turn on the hot water faucet, and wait patiently, or not so patiently for hot water, while cold water runs wasted down the drain.
This problem is caused by long pipe runs and can be solved in two ways: You could shorten your pipe runs by installing a point-of-use water heater next to each distant fixture, or less expensively you can install a hot water recirculating pump on your water line.
Grundfos makes a hot water recirculating pump that connects to your hot water line close to your water heater. The Grundfos system also includes a temperature–activated bypass valve. This valve connects the cold and hot water supply lines under the hot water fixture that is furthest from your water heater. The bypass valve contains a thermostat which measures the temperature of the hot water at your most distant fixture. When the hot water temperature drops below 85 degrees Fahrenheit, the recirculating pump is activated and pumps hot water into the line. The cooled standing water in the line is returned to the water heater through the cold water line. By circulating water in this way, hot water is made instantly available when any hot faucet is turned on, and water wastage is eliminated.
A hot water recirculating pump uses a small amount of electrical power. However, if the pump is repeatedly activated throughout the day and night, this electrical usage can add up. To minimize this use of electricity you can insulate your hot water pipes. By reducing heat loss you will also reduce the frequency of activation of the recirculating pump. Grundfos has another solution. Their models have an optional timer that can be attached to the pump. The timer can be preset so that the pump only comes on just prior to your main hot water usage times.
The Metlund D’Mand System and the Chillipepper CP6000 are recirculating pumps that are mounted below the sink that is furthest away from your water heater. When you need hot water you simply push a button, the hot water recirculating pump is activated, and you have instant hot water at your faucet. These recirculation systems work in the same way as the Grundfos system, but a timer is not required because electricity is only used when the button is pushed.