Recirculating Systems for Instant Hot Water: How It Works

How a recirculating systems for Instant Hot Water Works


The plumbing systems in American homes waste fathomless gallons of cold water during the wait for hot water. In most homes, cold water rests in plumbing pipes when water is not in use, and it requires purging before hot water can flow out. Two types of recirculating systems, however, eliminate waiting and wasted water by promptly providing hot water.

Demand-Controlled System

Initiated by a button, motion sensor or switch, a circulation pump returns the water standing in the pipes to the water heater and sends hot water through the pipes to the taps. Once hot water reaches the tap, a temperature-controlled switch signals the pump to stop.

Compared with other systems, a demand-controlled system uses less energy because the pump works only when hot water is wanted, but the process of returning the cold water to the water heater means a slightly longer wait time than gravity-fed systems offer.

Gravity-Fed System

Gravity-fed systems require a loop of plumbing lines: The first half of the loop carries hot water to the faucets, and the second half returns cold water to the water heater. Gravity brings cold water, which is denser and heavier than hot water, down to be reheated, and the lighter, reheated water rises back up the loop. Basically, gravity-fed systems are a continuous circuit of water.

This system only works in a home with the water heater placed lower than the hot water lines. Hot water is immediately available, but gravity-fed systems consume more energy than demand-controlled systems because the water heater is in continuous use.

If a home’s hot water heater is not located below the hot water lines, a pump can take the place of gravity in generating a continuous circuit. Again, hot water is instant, but energy use rises.

Installing a timer will reduce the amount of energy this type of system uses.

The system to choose depends upon the home, the budget and personal preference regarding energy, but both recirculating systems perform well the job for which they were created: reducing the time and water waste associated with waiting for hot water.

To learn more about Recirculating Systems and guidelines in the Raleigh area, call Poole’s Plumbing today and let one of our Plumbing Specialists help you choose the system that works best for your home.