What Is a Thermostatic Mixing Valve?

In this blog post, you’ll read:A thermostatic mixing valve is a gadget that fits before the hot taps. Yet, it mixes both cold and hot feed. However, it delivers the water to the consumer in warm conditions but at a safe temperature. It ensures that the water leaving the hot tap is not moving to so hot.
Table of Contents


A thermostatic mixing valve is a gadget that fits before the hot taps. Yet, it mixes both cold and hot feed. However, it delivers the water to the consumer in warm conditions but at a safe temperature. It ensures that the water leaving the hot tap is not moving too hot. Yet so that it burns or scolds the end user.

A Thermostatic Mixing Valve (TMV) is a specialized valve that blends hot water with cold water to ensure constant, safe outlet temperatures, thus preventing scalding. The valve uses a built-in thermostat to control the temperature of the mixed water discharged accurately. These valves are often used in domestic hot water systems and other applications where temperature control is crucial for safety and comfort.

Where is the Thermostatic Mixing Valve Located?

Typically, the TMV is located within the vanity or below the wash basin. Yet, some stylish tap also has TMV integrated into the unit. In some cases, we find the TMV used to service more than one wash basin. In other conditions, the thermostatic mixing valve may not be directly below the basin area.

Applications of Thermostatic Mixing Valves

  • Domestic Use: TMVs are vital in homes, especially showers and bathtubs, to prevent scalding and ensure comfortable water temperatures.
  • Healthcare Facilities: In hospitals and care homes, where occupants may have reduced sensitivity to temperature, TMVs are crucial to prevent burns.
  • Public Facilities: In places like gyms, swimming pools, or spas, where many people use water facilities, TMVs ensure consistent temperature.
  • Commercial Kitchens: To maintain sanitation standards and also protect staff from burns.
  • Industrial Processes: Certain manufacturing processes require water at consistent temperatures, making TMVs essential.
works of thermostatic mix valves
Works of thermostatic mix valves

How to Adjust a Thermostatic Mixing Valve?

A thermostatic mixing valve has three pipe connections. One pipe is used for cold and hot feed coming into TMV. It mixes, and warm feed exits the TMV and feeds the tap. We will see a cap sticking up from a small unit on the TMV. Once you end the lid, you will realize the small Allen key opening, which turns right or left. It is adjusting how hot to cold you want to mix in the hot, leaving feed. 

Main Parts of a Thermostatic Mixing Valve

A TMV has various internal components for mixing the cold with water. In TMV, a total of seven parts are present. Their essential elements are:

  • Cold water inlet port
  • Hot water inlet port
  • Slide valve
  • Thermostatic element
  • Mixing outlet
  • Cold water seat
  • Hot water seat
thermostat dimensions
thermostat dimensions

How Does a Thermostatic Mixing Valve Work:

A Thermostatic Mixing Valve (TMV) regulates water temperature by automatically blending hot water with cold water to achieve desired temperatures. It is designed to respond to the temperature, not the pressure of the incoming water.

  • Internal Thermostat: The core component of a TMV is its temperature-sensitive element. As the mixed water temperature increases, this element expands, reducing the hot water inlet flow and vice versa.
  • Temperature Control: If there’s a sudden decrease in cold water (like when a toilet is flushed), the valve reacts almost instantly, restricting the hot water flow to prevent scalding. Conversely, if the hot water supply drops, the valve allows more cold water, preventing sudden cold shocks.
  • Shutoff Feature: Advanced TMVs have a full shutoff response if the cold water supply fails, ensuring no hot water is delivered.

The thermostatic mixing valve is a prominent part of the bathroom. It mixes cold water with hot water. Yet, it ensures the water’s last temperature is suitable for human use. You may like to know this device as TMV. This device’s proper keeping is expected to keep it functional.

Knowing how a thermostatic mixing valve works is essential to use and introducing it. You should look familiar with all parts of this thermostatic mixing valve. With suitable keeping, you will like to implicate it for an extended period. The above seven features take responsibility for mixing cold and hot water. The process ensures the water we use to shower comes at a safe temperature. The phase-wise working processes of this device are:

How do I clean a thermostatic mixing valve? From Caleffi Hydronic Solutions

Step 1: Water Supply

In TMV, two ports are available on both sides for water application. These two ports are known as the cold inlet and the hot inlet port. As the name indicates, they supply cold and hot water, respectively. The cold port connects with the need to link with a water supply. On the other side, the hot port links with a hot heater.

Step 2: Internal Links

In TMV, there a slide valve is present at the center. When the water passes by the inlet ports, it will pass through the slide valve. The hot valve seat links the hot water inlets with a small opening of the slide valve. It is the lower part of the slide valve called the piston. Conversely, the cold valve seat links the cold inlet port with different openings. It is the upper part of the piston. Both cold and hot inlets bring the water to a mixing area.

Step 3: Water Mixing

A thermostat element is present in the piston as the intensity sensor. The water will pass through the cool and hot inlet ports. Then, at that point, water will try to stream beneath the mixing part through both valve cores. Yet, the sensor will control the water flow of both these sides.

The sensor will hold the cool water valve seat when it needs high-temperature water. Thus, the high-temperature water will stream to the mixing part. Also, when there is a need for cold water, the piston will control the hot valve seat. This action will allow the cold water to stream down.

Yet, they need cold and hot water to keep flowing in that part, and they will blend. The mixed water temperature will be proper due to the above heat sensor.

Step 4: Supplying blended water with the mixed water outlet

All the parts in the TMV ensure the acceptable temperature of the water. Yet, that water flows to the shower pipe for use. Yet, you’ll get mixed water with your temperature.

thermostatic valve works
Thermostatic valve works

Thermostatic Mixing Valve Regulations

Some necessary regulations that must be adopted are:

· Depending upon the use, the mixing water temperature remains within 38 – 45 degrees Celsius

· The pressure in the thermostatic mixing valve remains between 0.2 bar to 10 bar.

· Field testing is required every 12-month cycle to maintain machine efficiency.

Problems Associated with Thermostatic Mixing Valve

The main problems that you may face while using the thermostatic mixing valve are:

· The TMV pipes get dripped or leaked.

· The water flowing in any part faces disruption.

· The water temperature remains not suitable for your needs.

 Types of Thermostatic Mixing Valve

  • There are two main types of TMV, which is:
  • · TMV2
  • · TMV3

TMV2: The TMV2 is the type of valve used in a domestic environment. You can use it in some small business settings. TMV2 works under the pressure range from 0.1 to 5 bar.

thermostatic mixing valve
Thermostatic mixing valve

TMV3: TMV3 is the grade mixer valve that works the pressure up to 10 bar. It is built for the commercial environment. It is also required for healthcare, schools, and hospital environments. The TMV3s need to adhere to NHS D08 regulations. On the other side, TMV2 meets only two primary British standards. It applies in a healthcare setting. TMV3 is more powerful and robust. It is vital for a shower, changing rooms, and commercial-grade washing.

Specifications to Consider while Purchasing.

  • Material: Typically made from brass, but in specific applications, it might be constructed from zinc, aluminum, or even specialized plastics for corrosion resistance.
  • Size and Connections: Ranges from small household sizes (e.g., 1/2″ or 3/4″ and 1″) to larger industrial sizes. The type of connection (threaded, soldered, etc.) is essential to match the existing plumbing.
  • Temperature Range: Different TMVs have varied temperature control ranges. Ensure the valve you choose aligns with your requirements.
  • Flow Rate: Measured in gallons per minute (GPM) or liters per minute (LPM), selecting a valve that can handle your system’s flow rate is crucial.
  • Safety Standards: Ensure the TMV adheres to relevant safety and performance standards, such as ASSE 1017 or 1070 in the USA.

When selecting a TMV, it’s crucial to look at its specifications and ensure it’s fit for your specific application, ensuring both safety and efficiency.


Operating pressure range   Low-Pressure TMV2     EN 1287High-Pressure TMV2     EN 1111Low-Pressure TMV3DH Space D 08High-Pressure TMV3DH Space D 08
Maxi Static Pressure10 bar10 bar10 bar10 bar
Flow Pressure – Cold & Hot0.1 to 1 bar0.5 to 5 bar0.2 to 1 bar1 to 5 bar
Hot Supply Temperature55°C to 65°C55°C to 65°C55°C to 65°C55°C to 65°C
Temp differential (Hot Inlet-Outlet12°C12°C12°C12°C
Pressure and Temperature specifications

Thermostatic Mixing Valve Installation-The Step-by-Step Processes

A thermostatic mixing valve is a vital gadget for showering in the washroom. Yet, it will ensure your bath with mixed water at a protected and proper temperature. You can fix this gadget; the TMV fitting process isn’t complex. It will become more simple when you have the essential tools for installation.

Yet, doing this task will need your skill in this area. In any case, it is incredible to expect to be capable when doing it. You can take directions from a veteran while fixing it in that particular situation.

Material and Tools for Installing a Thermostatic Mixing Valve

You want a few materials and tools to make the joint among pipes and isolate them. First, you want to buy a thermostatic mixing valve from any shop close to your home.

The company will not collect the thermostatic mixing valve. This way, open the envelope and look at it to see whether all the parts are there. It would help if you had different instruments, too, for installation. In this way, every one of the fundamental materials and devices is:

  • An ideal thermostatic mixing valve
  • Hand gloves
  • Pliers
  • A couple of wrenches
thermostatic mix valve 1
thermostatic mix valve

Thermostatic Mixing Valve Installation: The Step-by-Step Processes

When you assemble each of the essential parts. You can begin installing the thermostatic mixing valve. The process of how to change a thermostatic mixing valve is as follows:

Step 1: Assemble the Thermostatic Mixing Valve

The thermostatic blending valve won’t collect when you get it. This way, you want to manage the entire device before introducing it. You will see two line connectors close to the valve. From the start, put those connectors in two loops. Then, on both the connectors, place an elastic washer too.

When you take the mixing valve, will be 3 plugs on each end. You need to remove those to fix the connectors there. There will be two side-mounted closes in the valve. It associates them with cold-water sources and high-temperature water. Then, at that point, attach those two connectors with the two side-mounted closes. One side of every connector will be free and join a nut there for a pipe link.

Step 2: Dry Out the Water

Before fitting the mixing valve, you must empty the water from the hot and cold lines. In the shower, you can also fix the thermostatic mixing valve under the sink. First, close the water associated with the sink or shower from the water tank.

In any case, some water will be left in the two lines. Open the shower and sink tap to kill the rest of the water. You can free the water from the two lines with extra valves.

Step 3: Installing the Thermostatic Mixing Valve

Then comes the piece of the thermostatic mixing valve fitting. Remove the joint head links of each of the three lines with a wrench. Then, you will see three lines coming to where you installed it. There will be a sign in the mixing valve body about which end to associate with which water source.

The red end should link the heated water source and the navy blue side with cold water. Apply some glue inside both connectors. Yet, afterward, put pipes inside them to stop spillage. To make the association solid, fix the new joints with pliers. It would help to associate the mixing valve’s opposite end with the shower or sink pipe.

Step 4: Temperature Controlling

There will be a top on the top of the mixing valve. Under that top, you will understand the temperature regulator. Turn that left to build the temperature and go right to diminish it. Then, check the water supply link and contribute to the mixed water blend at a suitable temperature.

3 way thermostatic mixed valve (copy)
3-way thermostatic mixed valve


Why do I need a TMV to install it?

Mixing the cold and hot water leads to burning. Yet, at the very least, total hot sanitation. TMV was installed to take care of this. It mixes the incoming cold and hot water when the handle turns. It prevents burning and provides the best flow, which is never too cold or too heat.

Why is a TMV so Important?

One of the main parts is building an efficient water heater with good circulation. Yet, good circulation means that hot water is heated. It does not spend time sitting free to wait for someone to use it before the heat transfers. Yet, it has more capacity to transfer the water from one loop to another. Yet, it moves more rapidly without the external pump’s external input energy.

For what reason does my shower temperature fluctuate?

Temperature vacillations in your hot water can imply that your boiler controls the temperature. Yet, it will continue to differ until it attains a set point. If you see enormous variations in shower temperature, have the water heater’s reserve tank checked or supplant it.

Where do you put a TMV?

The thermostatic mixing valve is generally introduced at the cool water shutoff. Yet, it should be mounted at the right point to the waterline. The valve is introduced before entering the boiler so that water enters when it identifies colder than set point temperatures.

What amount does a thermostatic mixing valve cost?

The typical expense of a thermostatic mixing valve is $50 or more. The cost can be between $5 to more than $50 for smaller valves utilized in heating if you’re introducing solar panels into your home. Yet, you might have the option to buy one free!

Is a thermostatic blending valve worth the effort?

If the setting for the high-temperature water is low, ensure there isn’t a bowl under it to collect bathwater if you are doing clothing or dishes. It should be 115 degrees or higher to get water in a bowl.

Thermostatic Mixing Valve: Final Thoughts:

One can get under severe stress about how to introduce a mixing valve. It’s anything but a complex process in the period with the critical tools and materials. Firstly, you might require support and advice from a few experienced individuals. When you learn it, you can play out the entire system of thermostatic mixing valve installation without help from anyone else.

Solutions For Waterworks Plumbing

Get quote Now

Free Sample with OEM

× How can I help you?