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Conserve Water With Hot Water Recirculation (Demo)

How often have you turned on the shower in the morning only to get an icy blast of cold water? For most, this is an everyday occurrence . Your solution has likely been to accomplish something else, like brushing your teeth, as the water heats up. Unfortunately, when you return to the shower, the water is hot, and probably has been for some time, meaning a fair amount of hot water has been lost down the drain. Over the course of a year, such waste of water and energy can prove costly both for you and the community.

Achieving instant and continuous hot water has long been a sought-after goal for homeowners and water heater manufacturers. No matter whether you have a tank-type or tankless water heater, though, hot water must always travel from the heater to the fixture, a distance that takes time to traverse. It means you must always wait for hot water. So what can you do to get truly “instantaneous” hot water? Place the water heater next to the shower?

Fortunately, you don’t have to resort to such extreme measures (although the size of a tankless water heater makes such a move far more practical). A solution that provides hot water with virtually no wait time is a hot water recirculation system. Recirculation operates through a “loop” created in a home’s or building’s plumbing system. In addition to supply lines connecting the water heater to each outlet, a recirculation system also contains either a return line back to the heater from each hot-water outlet or from only the farthest fixture. A circulating pump moves hot water through this loop — in some systems, even when there is no demand for hot water — resulting in “instant” hot water when the tap or shower is turned on.

You might be wondering how anyone can afford constant circulation, considering the energy costs of continuously heating and circulating this water. Although some water recirculation systems operate 24/7 (hotels), many are activated either by a timer (you preset a time for it to turn on), a motion sensor (it senses when you are approaching a fixture), or manually.

One more option exists for water recirculation systems — integrating the circulator into the water heater itself. The Noritz NRCP line of residential water heaters makes use of that technology. Instead of wasting energy by having hot water flow through the system continuously, an integral display on the front of the water heater allows homeowners to program the recirculation system only when needed, with a precision down to the hour.

An alternative, “auto” setting allows the system quickly to “learn” a household’s water-usage routines and automatically control the recirculation loop-activation times, allowing for immediate hot water when it is needed most.

“In order to maintain desired water temperature, the water heater’s recirculation control monitors the temperature of the water leaving the heat exchanger inside the water heater,” explains Randy Oshiro, Assistant Manager of Engineering at Noritz. “Once that temperature cools to a certain preset cutoff temperature, the burner kicks on again to heat the water to the set point temperature.”

An added feature of the NRCP is its internal circulation pump, which regularly circulates about half a gallon of warm water inside the unit, with a temperature sensor turning the burner on or off. This prevents freezing if the unit is not in use for an extended period during the winter. It also makes the water heat up more quickly since it’s already quite warm, allowing for an even shorter wait at the hot-water outlet.

In short, a hot water recirculation system keeps hot water flowing and ready for the moment someone turns on the faucet or shower. Time and temperature sensors control when the recirculation kicks in, ensuring that energy is not constantly being wasted. It truly provides heated water “on demand.”