Recirculation Systems: An Overview

Even the most efficient hot water systems struggle to get hot water to remote fixtures quickly. That’s where recirculation systems come into play. Learn more about hot water recirculation systems and how they can positively impact your hot water availability.

What Is a Hot Water Recirculating System?

Cold water enters your home’s water heater through a cold water line, and the unit turns the system into hot water.  The hot water heater then must transport water from the unit to the different fixtures throughout your home. Closer fixtures receive the hot water much more quickly than fixtures positioned far away from the water heater. 

A recirculation system refers to a plumbing system that promotes the regular flow of hot water throughout the entire house in an attempt to speed up hot water production at remote parts of the house. Recirculation systems are especially common in larger homes and multifamily dwellings.

A recirculation system consists of a dedicated hot water line loop and a recirculating pump. A circulation pump must be a subversive pump designed to operate under water. To avoid expedited corrosion due to the constant rushing water running through the pipes, use plastic pipes that don’t corrode when possible. 

A recirculating system can benefit both a tankless water heater and a tank water heater. Some people mistakenly assume that since a tankless hot water heater produces hot water on demand that all fixtures receive the water instantaneously, too, but the water still has to travel to the desired fixture. 

Not all water heaters are compatible with recirculation systems. Check your user manual to learn more about your particular water heater.

Benefits of Recirculation Systems

The main reason that a homeowner will want a recirculation system is that it increases convenience by providing virtually instant hot water. Homeowners notice a significant difference, especially in areas that take awhile to get hot water. 

When used wisely, recirculation systems can also improve efficiency. Heated water decreases in temperature when traveling long distances, especially if the pipes don’t have proper insulation. In order to get the desired water temperature to distant fixtures, homeowners may need to increase the unit’s temperature at the thermostat, increasing energy costs. A recirculation system eliminates the need for higher temperatures, and it can actually decrease energy use by 15 - 25% . 

Furthermore, getting hot water quickly prevents homeowners from running the water to wait for it to get warm, reducing water waste. Depending on the fixture in question and its flow rate, running water for 5 minutes waiting for the water to get cold can waste 10 gallons every time (assuming a fixture with a 2.0 GPM rate). If this occurs every day, that leads to about 300 gallons of wasted water every month (over 3500 gallons annually).

How Hot Water Recirculation Systems Work

An electricity-powered subversive pump creates a continuous flow of hot water through the system’s piping until it’s requested. 

The system keeps hot water near your appliances. When someone opens the valve to one of the fixtures along the system, the hot water is ready to travel to the desired fixture more quickly than in the case of a conventional hot water heater. 

A bypass valve controls the water flow through the circulation pipes.

Types of Recirculation Systems 

Integrated Loop

Integrated loops involve a pump installed at the furthest fixture from the water heater, as opposed to installing the pump at the water heater like in a dedicated loop system. 

A sensor turns the system on when water temperatures fall below a certain temperature (usually 85°F) and turns it off when water temperatures exceed a certain temperature (usually 100°F). 

Most integrated loop systems work best for retrofit systems already installed. 

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