Exploring ways to Restrict Legionella Exposure

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Water heater tanks are still the most popular choice for many homes because of their relatively low cost and instant access to heated water. The large supply of continuous hot water is convenient, but it comes with certain risks.

In domestic hot water systems, water heater tanks are normally set to no higher than 120° F to mitigate the growth of bacteria and prevent the risk of scalding. However, a growing concern in such systems is the persistence of legionella; a thermophilic bacteria that thrives in temperatures between 77° F and 113° F. Exposure to this bacteria is the cause of an infection of the lungs known as Legionnaires’ disease.

In response to this alarming trend, industry professionals have been exploring ways to restrict risk of legionella exposure. Temperatures in excess of 140° F are effective at killing and inhibiting growth of the bacteria in the water tank; but present a risk of scalding. To satisfy both concerns, the ideal solution is to adjust the high temperature output somewhere between the tank and the hot water tap.

Traditionally, this might be solved by connecting a thermostatic mixing valve at the water heater outlet to a tee at the cold supply, combining the two water sources for a tempered output. Though effective, this solution requires an assembly of several components, introducing multiple leak paths to the system, and resulting in installations that leave much to be desired in aesthetics and functionality.

The Water Heater Tempering Valve (WHTV) from Webstone®, a brand of NIBCO®, is the ultimate solution to safer hot water with consistent, expert looking results every time. On the supply inlet, a branch and an 18” flex hose connector provide cold water to the mixing valve. On the tank’s output, a valve mixes the cold water from the hose with the stored 140° F hot water in the tank, providing a new, safer output temperature that can be set between 86° F and 120° F.

To that point, the WHTV instantly upgrades any water heater, providing immediate access to more hot water than that of the tank’s storage capacity. Because the tempered output is partially sourced from the cold water supply outside of the tank, less untempered water is required from inside the tank. The result is greater available hot water output per gallons stored.

The WHTV is certified lead free and available in ¾” FIP × MIP or Press × MIP ends. For easy connection to recirculated hot water systems, the tempering valve includes an optional factory-plugged 1/2″ FIP recirculation port. Also available are an optional temperature gauge and installation kit that includes Webstone® ProPush™ flexible connectors to easily connect to copper, CPVC, or PEX.

For applications where untempered water makes sense, like dishwashers and washing machines, consider Webstone’s auxiliary solution: the Tempering By-Pass Valve. Suitable for residential or commercial applications, it’s installed at the hot water outlet, before the WHTV, and delivers ultra-hot water directly to these high-temperature appliances.

Simply put, the Water Heater Tempering Valve provides greater and safer hot water output per gallon stored. To learn more, visit webstonevalves.com/WHTV.

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