What is Thermostatic Mixing Valve?


The thermostatic mixing valve is a device that mixes hot and cold water together in the right proportions to produce a desired temperature. A thermostatic mixing valve is also known as a combination valve, mixing valve, or mixing faucet.


The thermostatic mixing valve is used in most of the modern bathroom and kitchen faucets. The valve is designed to provide hot and cold water to the user by adjusting the flow of water from the hot and cold water supply lines.

The mixing valves are available in many different designs, styles, shapes, colors, and sizes. They can be installed on both horizontal and vertical supply lines in the wall or floor.

The thermostatic mixing valves are available with single or dual handles and are supplied with a variety of controls. The temperature of the water can be adjusted by rotating the control ring on the handle.

The valves are available with a variety of temperature limits such as 40°C (104°F), 50°C (122°F), 60°C (140°F), 65°C (149°F), 70°C (158°F), 80°C (176°F), 90°C (194°F) or 100°C (212°F).

How does a Thermostatic Mixing Valve Work?

The thermostatic mixing valves have a mechanism that senses the temperature of the incoming hot water and adjusts the flow of cold water to maintain a set temperature. The temperature of the incoming hot water is sensed by an electronic sensor that is installed inside the valve body. The sensor has two probes that are connected to a bi-metallic strip inside the valve body. The bi-metallic strip bends when heated and this action moves a lever that opens or closes an internal shut-off valve to adjust the flow of cold water into the system. When cold water enters the system, it mixes with hot water already present in the pipes and cools down to match the temperature of incoming hot water.

Types of Thermostatic Mixing Valves

Thermostatic mixing valves are available in two types: single-stage and two-stage valves. Single-stage valves have one control ring for both hot and cold water supply lines while two-stage valves have two control rings for controlling each line independently. The two-stage valves allow for more precise temperature control than single-stage valves since each line can be set at different temperatures without affecting the other line. It is important to know what type of mixing valve you have before attempting any plumbing repairs or replacement since each type has its own unique features and characteristics that may make it incompatible with other systems in your house.

How to Repair or Replace a Thermostatic Mixing Valve

If your old thermostatic mixing valve stops working properly, you should replace it with a new one rather than repair it because repairing it may cost more than replacing it with a new one. If you have decided to replace your old thermostatic mixing valve, you need to turn off both hot and cold water supply lines before removing old unit from its mounting position on wall or floor. You can then remove old unit by disconnecting supply lines from it and unscrewing mounting screws that secure it to wall or floor if they are not concealed under decorative covers. After removing old unit, clean mounting surface where new unit will be mounted before installing new unit onto wall or floor using mounting screws provided with new unit. Be sure to connect supply lines to new unit before turning on hot and cold water supply lines again.

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