What You Need To Know About the Tempering Valve

One crucial component of any hot water system is the hot water tempering valve. This device holds the key to ensuring that the hot water flowing through your hot water tap and showers is not only consistently warm, but also safe for use.

Understanding the Tempering Valve and Its Role in Your Hot Water System

A tempering valve, also known as a thermostatic mixing valve (TMV), is a vital safety device installed in hot water systems – both storage tanks and tankless continuous flow models.

Its primary function is to regulate the temperature of water distributed from your hot water system to various outlets in your house. This valve blends hot water from your stored hot water supply with colder water from the mains, and ensures that the resulting mixture reaches a safe and consistent heat before it flows through your tap and showers.

The Needs of Gas and Electric Hot Water Systems

Hot water systems come in various shapes and sizes, each with its own unique characteristics and requirements. Whether you rely on a gas hot water system, an electric hot water unit, or a solar setup to provide your house with hot water, the role of the tempering valve remains consistent: to regulate heat and ensure a safe and reliable supply of heated water.

In gas hot water systems, for example, the tempering valve works in tandem with the heater to blend hot water from the storage tank or instantaneous unit with cold water from the mains, achieving the desired temperature before distribution. Similarly, in electric hot water systems, the tempering valve helps maintain consistent heat by adjusting the mix of cold and hot water as needed.

Why are Tempering Valves Important?

You might be asking yourself “Yes but do I need a tempering valve installed?” The short answer is yes. In addition to maintaining a consistent tank temperature, here are some reasons why.

Prevention of Scalding

Without a TMV or tempering valve, hot water from your system can reach dangerously high temperatures. This poses a risk of scalding, especially for vulnerable individuals like children, the elderly, or those with sensitive skin. Without proper heat regulation, accidents from scalding hot water can occur frequently, resulting in painful burns and potentially life-threatening injuries.

It doesn’t take long at all for people to experience the burning effects of scalding hot water. At 60 degrees Celsius, it takes a mere 5 seconds for an adult to suffer third-degree burns.

For a child, just one second. But with a tempering valve installed and set to the lower temperature of 50 degrees Celsius, that time extends to five minutes for both adults and children.

Shower head with hot water coming from it

Compliance with Regulations

In Australia, the installation of tempering valves to maintain a safe temperature is a legal requirement. The Plumbing Code of Australia mandates the use of tempering valves in various contexts, including residential dwellings, commercial buildings, and healthcare facilities, to mitigate the risk of scalding accidents and ensure compliance with industry guidelines.

To use South Australia as an example, the maximum water temperature changes depending on whether the system is in a private residence or public building. For water heaters used primarily for personal hygiene purposes in homes, the maximum temperature must not be higher than 50°C for fixtures such as showers, baths and hand basins.

However, in public buildings used and occupied by children, elderly people and people with disabilities, that maximum temperature is reduced to 45°C. Examples of these public buildings include nursing homes and primary & secondary schools.

Protection Against Bacterial Contamination

Tempering valves also play a crucial role in safeguarding against bacterial contamination, particularly from harmful pathogens such as Legionella bacteria. These harmful bacteria thrive in water that is either too hot or too cold, making them a significant concern in hot water systems where maintaining a specific temperature is paramount.

By maintaining water temperatures within a safe range, tempering valves help mitigate the risk of bacterial growth, thus reducing the likelihood of waterborne illnesses and promoting healthier living environments.

Types of Tempering Valves

There are three different types of tempering valves available, including:

Thermostatic Mixing Valve

The most common type of tempering valve, thermostatic mixing valves (TMVs) rely on mechanical components such as wax-filled cartridges or bi-metal strips to regulate water temperature. These valves automatically adjust the mix of hot and cold water to maintain a predetermined set temperature, regardless of changes in water pressure or temperature.

Sliding Valve TMVs

Sliding Valve (SV) TMVs work best in settings where manual temperature adjustment is preferred or required. These valves feature a manual control mechanism that allows users to adjust the mix of hot and cold water by moving a sliding lever or knob. SV TMVs are often used in residential settings where users prefer the flexibility of manual temperature control or in applications where electronic components may be impractical or unnecessary.

Electronic Mixing Valves

For homeowners seeking advanced temperature control and customization options, electronic mixing valves provide an innovative solution. These valves utilize electronic sensors and actuators to monitor and adjust water temperature with exceptional accuracy and reliability. An electronic hot water mixing valve offers features such as digital temperature displays, programmable temperature settings, and remote control capabilities, allowing users to fine-tune their hot water experience to their exact preferences.

Installation and Maintenance

Installing a tempering valve should always be entrusted to qualified and licensed plumbers who possess the necessary expertise and experience. A licensed plumber will ensure that the valve is installed correctly, according to manufacturer specifications and local plumbing regulations. Proper installation is essential for optimal performance and longevity of the tempering valve, as well as compliance with safety standards.

Ideally, a hot water tempering valve, like most plumbing systems, should be serviced at least once a year by a qualified technician to maintain optimal performance and compliance with safety standards. If necessary, replacement hot water systems may need to be installed.

Empty bathtub

Choosing the Right Tempering Valve

When selecting a tempering valve for your hot water system, consider factors such as:

  • Flow rate – One of the first factors to consider when choosing a tempering valve is its compatibility with the flow rate of your hot water system. The valve should be able to accommodate the maximum flow rate of your system without causing any reduction in water pressure or compromising performance.
  • Quality and reliability – Invest in a high-quality tempering valve from a reputable manufacturer to ensure long-term reliability and performance. Look for valves that are constructed from durable materials, such as brass or stainless steel, to withstand the rigours of daily use and maintain their integrity over time.
  • Temperature control – Temperature controllability is another critical consideration when selecting a tempering valve. Look for a valve that allows you to set the desired water temperature accurately and maintain it consistently, regardless of changes in water pressure or temperature. TMVs are known for their precise temperature control and reliability, making them a popular choice for residential and commercial applications.
  • Compatibility – Ensure that the tempering valve you choose is compatible with the type of hot water system you have installed in your home. Whether you have a gas, electric, or solar-powered system, the valve should integrate seamlessly with your existing infrastructure to ensure optimal performance and reliability. You must also ensure that it meets the requirements of the Plumbing Code of Australia.

Tempering Valves in a Hot and Cold Water System

In summary, tempering valves play a crucial role in maintaining the safety and efficiency of your hot water system. By regulating water temperature and preventing scalding accidents, these valves provide peace of mind for homeowners.

If you’re considering a new hot water system or need to replace an existing one, make sure to include a tempering valve in your setup. Consult with a licensed plumber for advice on the best valve for your specific needs and enjoy a reliable supply of safe and comfortable hot water in your home.

Please note: This information is provided for advice purposes only. Regulations differ from state to state, so please consult your local authorities or an industry professional before proceeding with any work. See 23 Hour Plumbing’s Terms & Conditions here.

Last Edited on: 13th March 2024

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