How to install a thermostatic mixing valve?


How to install a thermostatic mixing valve?


The water temperature in a hot water heater needs be kept at approximately 140 degrees Fahrenheit to limit the potential of the unit becoming a breeding ground for Legionella, the bacteria that cause Legionnaire’s disease. However, water can cause scalding at approximately 120 degrees Fahrenheit, creating a difficult dilemma for homeowners. To address this issue, many areas now require the installation of thermostatic mixing valves by code in residential applications, with exceptions such as a direct line to a dishwasher. Thermostatic valves attach to both the cold water line and the hot water line to alter the cold water to hot water ratio, which allows the temperature of water from the tap to be safe.

Step One

Check local building codes to ensure all laws are followed with regard to what qualifications are required by code when installing the mixing valve.

Step Two

Turn off the main water supply and open all faucets to allow water in the lines to drain. Be patient as this may take some time.

Step Three

Select a location that will be accessible for cleaning, adjustment and servicing. Also note that dishwashers may benefit from hotter water. Run a separate line directly from the water heater to the dishwasher or to other appliances that might require higher temperature water to avoid using the mixing valve in these cases.

Step Four

Solder the connections to the thermostatic valve before attaching it to prevent damaging the gaskets. Ensure that the solder is safe for potable water to prevent harmful elements from having contact with water used for drinking.

Step Five

Tighten the connections to the valve using a wrench.

Step Six

Turn the water on and check the temperature of the water from a faucet using a thermometer. Allow some time for the hot water to reach the faucet before recording the temperature.

Step Seven

Turn the hand wheel to adjust the dial to the desired temperature. The instructions that come with the thermostatic valve should indicate what the current assumed water temperature is without the mixing valve attached and what difference a one-degree turn will equal in percent.


Leave A Reply

By continuing to use the site, you agree to the use of cookies. Full Cookie Disclosure...

The cookie settings on this website are set to "allow cookies" to give you the best browsing experience possible. If you continue to use this website without changing your cookie settings or you click "Accept" below then you are consenting to this.