Demand Hot Water Recirculating System

Demand hot water recirculating systems can save water and energy in some situations. Potential benefits of installing a demand recirculating system during your next new construction or home retrofitting project, include:

  1. Demand recirculating pumps have the potential to solve the problem of a long wait for hot water at a distant fixture, while simultaneously saving energy, water and money.
  2. You no longer have to send cold water down the drain while waiting for warm water. Instead, recirculating pumps rapidly pull hot water from a water heater, while simultaneously send cool water from the hot water lines back to the water heater to be reheated and reused. Demand systems can be controlled by the push of a button, a timer, or motion sensor.
    • Recirculation systems that operate continuously have the potential to use more energy, due to energy spent pumping and hot water energy lost from the pipes, than the energy saved by reducing hot water waste.

How it Works. In a conventional system with a central water heater, any cold water standing in the pipes between the heater and the point-of-use is dumped down the drain as hot water travels from the heater.

In a demand recirculating system, when the system is activated the pump starts recirculating cooled water that's been sitting in the hot water line and sends it back to the water heater through the cold water line. When the water reaches a desired temperature a control turns off the pump. This process is similar to turning on the hot water faucet and letting the water run until it gets hot, but instead of the water going down the drain, it is simply returned back to the water heater—saving energy and water.

In an integrated loop system, hot water is re-circulated intermittently. Hot water is returned to the water heater through the cold water pipes. This process raises the temperature of the cold water slightly, but it returns to the usual cold temperature in a short time.