Best Thermostatic Mixing Valve: Reviewed and Rated

best thermostatic mixing valve

Every year, thousands of people suffer from severe scalds due to overly hot tap water. A study by Shields and colleagues highlights the dangers, showing that from 2016 to 2018 in the United States, tap water scald burns led to 52,088 emergency department visits, 7,270 hospitalizations, and 110 deaths. Remarkably, 35.4% of these hospital visits and 16.1% of emergency room cases involved burns to multiple body parts. These worrying numbers highlight the important role of a thermostatic mixing valve in keeping water temperatures safe and preventing such injuries.

In this article, we will look at how a thermostatic mixing valve can make a big difference in safety at home or work compared to a regular tempering valve. We will discuss the benefits, key things to think about, and the best brands of thermostatic mixing valves to help you choose wisely.

What Does a Thermostatic Mixing Valve Do?

A thermostatic mixing valve (TMV) is a device designed to precisely control the temperature of water coming out of your taps, ensuring it is safe and consistent. This valve is crucial in preventing the risk of scalding from hot water.

How a TMV Works

  • The valve blends hot water with cold water to achieve a set temperature.
  • A thermostat within the valve detects the temperature of the incoming water.
  • If the water is too hot or too cold, the thermostat adjusts the ratio of hot to cold water to maintain stability.

This process ensures that the water at your tap is always at a safe, pre-set temperature.

Thermostatic Mixing Valve vs Tempering Valve

While both a thermostatic mixing valve and a tempering valve are designed to control water temperature, they differ significantly in functionality and application. Here are the main differences:

  • Temperature Control Precision: A thermostatic mixing valve offers precise temperature control, adjusting the water mix in real-time as the temperatures of the incoming hot and cold water change. This makes them ideal for more sensitive applications. In contrast, a tempering valve often provides less precise control, making it more suitable for applications where slight variations in output temperature are acceptable.
  • Safety Features: TMVs are generally equipped with safety features that prevent water from getting too hot if there's a failure in the cold water supply, a crucial feature in settings like healthcare and childcare. A tempering valve may not have this level of safety mechanism.
  • Applications: Thermostatic mixing valves are used in environments where exact temperature control is critical, such as in hospitals or care homes. Tempering valves, on the other hand, are typically used in less critical settings like residential water systems where the main goal is to reduce the likelihood of scalding.
  • Regulation and Compliance: TMVs usually meet more stringent regulatory standards for temperature control, which are necessary in many commercial and public buildings. Tempering valves may not meet these higher standards but are still effective for general residential use.

Advantages and Disadvantages of Thermostatic Mixing Valves

After understanding how a thermostatic mixing valve functions and how it differs from a tempering valve, it's important to consider the pros and cons of installing a thermostatic mixing valve. This will help you make an informed decision based on your specific needs and the environments in which the valve will operate.

Advantages of Thermostatic Mixing Valves

  • Consistent Water Temperature: A thermostatic mixing valve ensures that water reaches a consistent, pre-set temperature, reducing the risk of sudden changes that can lead to scalding.
  • Energy Efficiency: By efficiently mixing hot and cold water to achieve the desired temperature, TMVs can help save energy by reducing the need for excessive heating of water.
  • Safety Features: These valves are designed with built-in safety mechanisms that shut off the hot or cold water flow in case of a supply failure, significantly reducing the risk of burns.
  • Versatility: Thermostatic mixing valves are adaptable and can be used in various settings, from residential homes to high-demand commercial environments like hospitals.

Disadvantages of Thermostatic Mixing Valves

  • Higher Initial Cost: Compared to standard mixing valves, TMVs can be more expensive due to their advanced technology and additional features.
  • Maintenance Requirements: To keep them operating effectively and safely, thermostatic mixing valves may require more regular maintenance and periodic checks than simpler valves.
  • Complex Installation: Installation of a TMV can be more complex, requiring professional setup, especially in systems that were not initially designed for such advanced hardware.
  • Potential for Wear and Tear: Because TMVs contain more intricate internal components, they may be more susceptible to wear and tear, particularly in areas with hard water.


Thermostatic Mixing Valve Buying Considerations

When considering purchasing a thermostatic mixing valve, there are several factors to keep in mind to ensure that you select the right valve for your specific needs. Here’s a closer look at some critical considerations:

Temperature Range and Control

The temperature range and control capabilities are crucial in a thermostatic mixing valve. Look for valves that offer a wide range of adjustable temperatures, allowing for flexibility depending on different users' needs and applications. It’s important that the mixing valve can maintain a consistent output even when the input temperatures vary significantly, to ensure safety and comfort.

Flow Rate

The flow rate of a thermostatic mixing valve determines how much water it can process and deliver at a consistent temperature. Higher flow rates are necessary for environments where water is used by multiple outlets simultaneously. Ensure that the mixing valve you choose can handle the peak water usage expected in your setting without a drop in performance.

Size & Compatibility

Size and compatibility are key when integrating a thermostatic mixing valve into your existing water system. The valve should physically fit where you intend to install it, and it must be compatible with the pipe size and type in your system. Incorrect sizing can lead to reduced efficiency and even damage to your water mixing valve setup.

Material Quality

Material quality affects the durability and longevity of a thermostatic mixing valve. Opt for valves made from corrosion-resistant materials, such as brass or stainless steel, that can withstand the rigors of daily use and varying water qualities. High-quality materials help prevent leaks and degradation over time, ensuring your water mixing valve remains effective and safe.

Safety Features & Certifications

Safety features and certifications are important in choosing a thermostatic mixing valve. Look for valves with built-in anti-scald mechanisms and thermal shut-off capabilities, which prevent water from becoming dangerously hot. Additionally, ensure the mixing valve has relevant certifications from recognized standards organizations, confirming it meets safety and performance guidelines.

Here are some of the major certifications related to thermostatic mixing valves:

  • ASSE 1016: This certification, issued by the American Society of Sanitary Engineering, specifies performance requirements for individual shower, tub, and combination tub/shower valves. It ensures that the thermostatic mixing valve can maintain a stable water temperature within safe limits to prevent scalding.
  • ASSE 1070: This standard is also from the American Society of Sanitary Engineering and focuses on water mixing valves for fixtures such as sinks, lavatories, and bidets. It covers valves intended to control the temperature of the delivered water to prevent scalding.
  • NSF/ANSI 61: Issued by the National Sanitation Foundation and the American National Standards Institute, this certification relates to the effects of a valve on water quality. It ensures that the materials used in the thermostatic mixing valve do not leach harmful contaminants into the water.


Best Thermostatic Mixing Valves: Top 4 Brands

Watts Thermostatic Mixing Valve

The Watts LFMMVM1-UT Lead-Free Thermostatic Mixing Valve excels in providing precise temperature control for a range of uses, from residential safety to commercial efficiency. It allows for easy adjustment within a broad temperature range, making it a versatile choice for various settings. While the valve ensures compliance with critical safety and environmental standards, its higher flow rate capability may not be necessary for smaller, single-fixture applications, potentially leading to underutilization in less demanding environments.

Adjustable Temperature: Set anywhere between 80°F and 120°F.
Eco-Friendly Material: Constructed from lead-free brass.
Reliable Mixing: Utilizes a solid wax hydraulic principle.

Temperature Range: 80°F to 120°F Flow Rate: 0.5 gpm to 12 gpm Size: 1/2" Material: Lead Free Brass Certifications: ASSE 1017, ASSE 1069, ASSE 1070, IAPMO cUPC

Cash Acme Thermostatic Mixing Valve

The Cash Acme Thermostatic Mixing Valve is celebrated for its capability to mix hot and cold water, delivering it at a safe and controlled temperature of 120°F, making it perfect for compact spaces. The valve's compatibility with a wide range of pipe types, including PEX and CPVC, adds to its versatility. Despite its many benefits, the lack of specified certifications might be a concern for those needing to meet stringent compliance standards.

Wide Compatibility: Works with various types of piping.
High Durability: Made from durable lead-free brass.
Tool-Free Installation: Easily installed without special tools or soldering.

Temperature Range: 85°F to 130°F Flow Rate:N/A Size: ‎3/4" Material: Lead Free Brass Certifications: N/A

Speakman Thermostatic Mixing Valve

The Speakman A-TMV Under Counter Thermostatic Mixing Valve stands out for its extremely compact design, making it the smallest footprint ASSE 1070 certified valve on the market, ideal for under-counter installations in limited spaces. It efficiently regulates water temperature to ensure the delivery of safe and tepid water, which is particularly useful in various faucet applications. While its small size and precise temperature control are major advantages, the minimal flow rate might not be suitable for high-demand applications where larger volumes of tempered water are needed quickly.

Compact Size: Easiest to fit in tight under-counter spaces.
Precise Temperature Regulation: Ensures the delivery of tepid water.
Easy Installation: Features 3/8" compression male threaded inlets and outlet for straightforward setup.

Temperature Range: ‎Tepid Water Temperature Flow Rate: minimum 0. 35 gpm Size: ‎3/8" Material: Rough Brass Certifications: ASSE 1070

Zurn Wilkins Thermostatic Mixing Valve

The Zurn Wilkins ZW1070XL Aqua-Gard Thermostatic Mixing Valve is highly versatile, making it an ideal choice for both residential and light commercial applications. It is designed to prevent scalding and limit bacterial growth such as legionella, providing enhanced safety across various installations. Despite its many benefits, the specificity of temperature range may limit its use in applications requiring either cooler or hotter water outputs.

Versatile Installations: Compatible with multiple fixture types.
Safety Focused: Protects against scalding and bacterial growth.
Energy Efficient: Helps reduce lifecycle energy costs.

Temperature Range: 95°F to 115°F Flow Rate: N/A Size: 3/4" Material: Bronze Certifications: ASSE, IAPMO, CSA, NSF/ANSI 61-9

Role of TMVs in Eye Wash Stations

Moving from general water safety applications to more specific needs, the thermostatic mixing valve plays a crucial role in eye wash stations and emergency shower stations. The thermostatic mixing valve ensures that the water dispensed in these safety stations is at a safe, tepid temperature, preventing any additional harm from either too hot or too cold water during an emergency and adhering to ANSI Z358.1 standard.

Thermostatic mixing valves are essential in eye wash stations because they help mitigate the risk of thermal shock or scalding when a person’s eyes or skin need immediate flushing. In emergency situations, delivering water at a consistent and safe temperature can be crucial for the effectiveness of the first aid process and can significantly impact the recovery outcome.

Typically, the water mixing valve is installed close to the eye wash station to quickly adjust the water temperature as it flows to the point of use, ensuring rapid response without delays. The placement and performance of a water mixing valve in these settings not only adhere to safety regulations but also provide peace of mind that first aid measures will be effective and safe when they are most needed.

Recommended Tempering Valves for Eye Wash Stations

The following recommendations focus on valves specifically designed to handle the demands of an eyewash mixing valve, ensuring that water is delivered at a safe temperature promptly. Each brand listed below has been selected for its reliability and performance in emergency situations, ensuring that the mixing valve for eyewash station meets the strict standards required for occupational safety.

 Bradley Eyewash Mixing Valve
  • High Flow Rate: Provides 8 GPM at 30 PSI, suitable for effective emergency response.
  • Universal Mounting: Ensures compatibility with various installation setups.
  • Safety Standards Compliance: Meets ANSI Z358.1 and ASSE 1071, ensuring reliability in safety applications.


Leonard Thermostatic Mixing Valve
  • DURA-trol® Bi-metal Control: Ensures stable temperature regulation for safety.
  • Locked Temperature Setting: Maintains water at a safe 85°F, with a high limit stop at 90°F.
  • Built-in Safety Features: Includes an internal bypass for cold water delivery if the hot water supply fails, maintaining a minimum flow of 4 GPM at 30 PSI.


 Guardian Thermostatic Mixing Valve 
  • Adjustable Temperature Range: Allows setting tepid water between 65° - 95°F.
  • High Capacity: Handles up to 13 gallons per minute, enhancing the effectiveness of emergency stations.
  • Monitoring Tools: Equipped with temperature and pressure gauges for optimal operational awareness.


     Haws TMV for Eyewash Stations
    • Thermostatic Mixing: Balances hot and cold water to ensure safe output temperatures.
    • Fail-Safe Design: Features cold water bypass valves that activate if hot water pressure drops.
    • Standard Compliance: Adheres to ASSE 1071 recommendations for safety and performance in eyewash stations.

    Thermostatic Mixing Valve FAQs

    What are the disadvantages of thermostatic mixing valves?

    Thermostatic mixing valves can be more expensive than other types of valves due to their advanced technology. They also require regular maintenance to ensure they function properly and do not wear out prematurely, especially in areas with hard water.

    Is a thermostatic mixing valve worth it?

    Yes, a thermostatic mixing valve is often worth the investment for its ability to consistently provide water at a safe temperature, which can prevent scalding injuries and contribute to energy savings by efficiently mixing hot and cold water.

    What happens when a mixing valve fails?

    When a mixing valve fails, it typically stops regulating the temperature correctly, which can result in water that is too hot or too cold. This can pose safety risks or lead to discomfort and potential damage to plumbing systems if not addressed quickly.

    Where is the water mixing valve located?

    A water mixing valve is usually installed where the water lines converge in your plumbing system, often near the water heater or within major water fixtures in homes or commercial buildings. Its placement is strategic to facilitate easy maintenance and effective temperature control.

    What is the difference between a tempering valve and a mixing valve?

    A tempering valve is specifically designed to mix hot water with cold water to a preset temperature to prevent scalding but typically offers less precise control compared to a thermostatic mixing valve. Thermostatic mixing valves offer more accurate temperature adjustments and are better suited for applications requiring strict temperature regulation.

    Can I change the tempering valve myself?

    Changing a tempering valve yourself is possible if you have basic plumbing knowledge and the necessary tools; however, it is recommended to consult with or hire a professional plumber to ensure the job is done safely and in compliance with local plumbing codes, especially if you are not familiar with your plumbing system's specifics.

    The material provided in this article is for general information purposes only. It is not intended to replace professional/legal advice or substitute government regulations, industry standards, or other requirements specific to any business/activity. While we made sure to provide accurate and reliable information, we make no representation that the details or sources are up-to-date, complete or remain available. Readers should consult with an industrial safety expert, qualified professional, or attorney for any specific concerns and questions.


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    Author: Herbert Post

    Born in the Philadelphia area and raised in Houston by a family who was predominately employed in heavy manufacturing. Herb took a liking to factory processes and later safety compliance where he has spent the last 13 years facilitating best practices and teaching updated regulations. He is married with two children and a St Bernard named Jose. Herb is a self-described compliance geek. When he isn’t studying safety reports and regulatory interpretations he enjoys racquetball and watching his favorite football team, the Dallas Cowboys.