RE-CIRCULATING SYSTEMS

A hot water recirculation system is a plumbing system that moves hot water to fixtures quickly without waiting for the water to get hot. Rather than relying on low water pressure, common in most water lines, recirculating systems rapidly move water from a water heater to the fixtures.

SYSTEM TYPES

Dedicated Loop:
In this system, a circulation pump is installed on a pipe near the bottom of the water heater tank, where cooler water returns to be reheated. The hot water line is routed in a continuous loop throughout the home, running close to each plumbing fixture. A short branch line connects the loop to each hot water valve. Because hot water is constantly circulating through the system, opening a valve delivers hot water almost instantly.

Integrated Loop:
This system is commonly used for retrofit applications but can also be installed in new construction. It features a circulation pump located beneath the plumbing fixture farthest from the water heater. The pump uses a temperature sensor to activate when the water temperature drops below 85°F and shut off once it reaches 95°F. Newer models offer adjustable settings ranging from 77°F to 104°F.

Unlike continuous systems, hot water in an integrated loop is recirculated only as needed. The water returns to the heater through the cold water lines, temporarily warming the cold water slightly before it quickly returns to its normal temperature.

Activation
Hot water re-circulation systems are most commonly activated by either a thermostat or a timer. Systems that use a thermostat or timer automatically turn the pump on whenever the water temperature drops below a set point, or when the timer reaches a certain setting. These systems ensure that hot water is always available at the faucet.

Do Recirculation Systems Really Save Energy and Water?
Whether operated manually or automatically, recirculation systems reduce the amount of water wasted while homeowners wait for hot water to reach the desired temperature. Compared to traditional water distribution systems, they offer several key benefits:

Time savings: Hot water reaches faucets almost immediately, adding everyday convenience.
Water conservation: According to data from the U.S. Department of Energy and the U.S. Census Bureau, U.S. households waste an estimated 400 billion to 1.3 trillion gallons of water each year while waiting for water to heat—nearly the equivalent of 2 million Olympic-sized swimming pools.
Reduced municipal energy waste: The DOE estimates that 800 to 1,600 kilowatt-hours of energy per year are used to treat and pump water that ultimately goes unused as occupants wait for tap water to warm.

However, continuously running recirculation systems can increase energy use. A modest-sized pump operating nonstop may consume 400 to 800 kilowatt-hours annually. In addition, poorly insulated hot water pipes can lead to heat loss, causing the water heater to run more frequently. While this extra heat may be helpful during colder months, it can raise indoor temperatures during summer and potentially increase air-conditioning costs.