How to Identify an Anti-Scald Shower Mixing Valve

Updated July 20, 2017

Monitoring the temperature of water entering your home is necessary to ensure water safety for you and your family. Anti-scald valves used with water heaters are often called "tempering valves" or "mixing valves." An anti-scald valve mixes cold water in with the outgoing hot water to assure that hot water reaching a building fixture is at a temperature low enough to be safe. Identifying an anti-scald shower mixing valve is vital to ensuring safe water temperatures.

Find the location of the water heater in question, in order to identify the anti-scald mixing valve. An anti-scald mixing valve can be installed at or near the water heater, or at the tankless coil or other hot water source, so that scald protection is provided even if the water heater is set to a high temperature.

Search for a valve that has a temperature control knob, an input knob for hot water, an input knob for cold water, and an output knob for the tempered water. The anti-scald valve contains an internal temperature sensor which permits the valve to add cold water to the outgoing hot water in order to limit the temperature of the hot water leaving the valve.

Identify an anti-scald mixing valve by identifying the valve containing three input/output valves and a temperature control knob. If these parts are present, then you have identified an anti-scald shower mixing valve used to control the temperature of water coming from the water heater, and into the home.


While these valves may show a target temperature on the valve setting knob, the actual water temperature that comes out of the faucet or tap will vary and may be hotter or cooler than the actual target temperature set.

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About the Author

Stephanie Cates began writing professionally in 2010. She has vast knowledge of cross-cultural studies, individual and team sports and international development. She holds a Bachelor of Arts in clinical psychology from Point Loma Nazarene University in San Diego and is pursuing a Bachelor of Arts in education and community development from the Institute of Global Outreach Developments International in Nashville.