34/Plumbing Engineer March 2021

By James Dipping

W

ith the world's heightened focus on infec- tion control, local municipalities, the Centers for Disease Control and Prevention, the U.S. Occupational Safety and Health Administration and other plumbing authorities are calling for buildings to use several methods to reduce the development of waterborne pathogens. One of the foremost measures recommended by the CDC and OSHA is maintaining higher domestic hot water temperatures throughout your facility. The idea is simple. The higher the temperature, the better the infection control. While COVID-19 isn't waterborne, Legionella and other waterborne pathogens and bacteria that can wreak serious havoc on a facility and its occupants are on the rise. An October 2020 article in the Smithsonian Magazine notes that in 2018 (the most recent data collected), the CDC reported the highest number of Legionella cases ever in the United States (http://bit. ly/3cxUNMG). Maintaining higher temperatures across a building's plumbing system will improve infection control in the domestic water system and reduce the potential for Legionella development. Yet this practice is in direct opposition to the industry push for energy-efficient design over the last decade that led many engineers and building owners to revamp their approach to plumbing infrastructure and lower building-wide distribution and circulation temps. If the industry is to transition to higher hot water sup- ply and return temperatures, plumbing engineers will need to shift from central temperature control applica- tions to point-of-use control. This allows a building operator to maintain higher temperature circulation and reduce the temperature at the point of use. Establishing a New Building Temperature Set-Point The CDC (http://bit.ly/2YF6SaJ) and OSHA (http:// bit.ly/3oEDuMj) are calling for buildings to circulate temperature across their plumbing infrastructure at a minimum of 122 F to 124 F. This is about 10 to 15 degrees higher than most facilities are currently operat- ing. Making this change is a lot more complicated than raising the circulating water temperature by 10 degrees. For one, water will need to be introduced into the plumbing loop at a minimum of 125 F in a smaller build- ing and possibly up to 135 F in larger buildings to circu- late and return water regularly at 124 F or above. These higher source-distribution temperatures are needed to account for normal temperature drops within the piping system. Higher distribution and return water temperatures building-wide also mean engineers and building opera- tors must focus on scald prevention. Even a 10-degree increase in water temperature can have a serious effect on scalding at a faucet. As a general rule of thumb, it takes 10 seconds to get a serious scald from 135 F and only three seconds at 140 F. Prevent Scalding with Proper Valve Specification Scald prevention can be attacked by specifying the right valves for your temperature set-points across a facility. From faucets to showers to emergency fixtures,

As Infection Control Increases Building Water Temperature, Scalding Prevention Takes Center Stage

Plumbing engineers will need to shift from central temperature control applications to point- of-use control.