Thermostatic mixing valve (TMV) is the complicated name for a device that blends hot and cold water together to ensure that the water temperature is at a safe level before it comes out of a faucet. Typically, hot water is stored at a temperature high enough to kill germs (and scald skin), so it is important that a TMV is installed correctly so that faucet users don’t get burnt. Here are three things to consider before attempting an installation.
1 -- Check the Pressures
Make sure to check the pressures of both the cold and hot water lines. If the pressure of either of these water lines differs more than 10 pounds per square inch from the other, then even a properly installed TMV may not function properly. The water line with the greater amount of pressure will throw off the balance of the blended water by forcing too much water of that particular temperature through the TMV. A balancing valve can be installed on the pipes before the TMV to fix this problem.
2 -- Solder Prior to Assembly
Always solder all necessary plumbing joints before assembling the TMV so that the sealing gaskets do not melt or warp. If a joint must be soldered with the TMV attached, remove the check valves and any non-metal sealing valves first. Heat can also transfer from a pipe into the TMV, so be sure to give the unit a proper amount of time to cool off before reassembling it.
3 -- Install the Valve Where It Is Accessible
Thermostatic mixing valves may need occasional cleaning and maintenance. For this reason, it is wise to install them in an area easily accessible. To clean these units, simply use a screwdriver to remove the top piece and remove the inner diffuser and spring. Do not soak these parts in chemicals that could damage the valve, but rather, soak them in vinegar to loosen any debris and then scrub them with a brush.