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When you turn the tap on in your home or workplace, you expect water at the correct temperature to be delivered – whether that be hot, cold, warm or something in between.

The wonderful little device that helps achieve the right hot water temperature is either a tempering valve or a thermostatic mixing valve, which can easily be mixed up but are actually two different things. To help you decipher between the two and figure out which one is best for your needs, take a read of the below information or give Brisbane Plumbing and Drainage a call on 1300 616 203 and we would be happy to assist.

What is a thermostatic mixing valve?

A thermostatic mixing valve, or TMV, is a great little gadget that blends both hot and cold water together to achieve a particular, predetermined water temperature when delivering water through a faucet.

How does a thermostatic mixing valve work?

A TMV works by mixing hot and cold water together to achieve a particular temperature (within 1°C +/-) to be delivered in various. The temperature is usually preset by a plumber or a qualified tradesperson who has installed the device, and the element within a TMV that is sensitive to thermal activity automatically arranges the appropriate levels of hot/cold water to create the correct temperature of the liquid.

What is a tempering valve?

A tempering valve is a temperature-sensitive 2-inlet or 3-inlet mixing valve which pulls water from your hot water system, mixes it with cold water and delivers it to a faucet. General household use requires hot water to be no hotter than 60°C, however, appliances such as dishwashers and washing machines may have differing settings.

How does a tempering valve work?

Tempering valves are adjustable and temperature-activated, meaning they moderate hot water flow when necessary to ensure water isn’t too hot when it is delivered to a tap. Hot water that is stored in a hot water storage system should be kept at a temperature of at least 60°C, however, water should be delivered through a faucet at a maximum of 50°C. A tempering valve works by blending hot water with cold water so it flows through your tap at the correct temperature, within 3°C +/-.

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

Despite a TMV and a tempering valve having similar jobs, there are some differences between them including :

  • Tempering valves are accurate to approximately 3°C +/- but TMVs are accurate to around 1°C +/-
  • TMVs are more expensive than tempering valves
  • TMVs are quicker to respond to temperature changes
  • TMVs last longer than tempering valves
  • Tempering valves are usually replaced, not repaired when needed. TMVs are generally repaired where possible
  • Plumbers must have a specific TMV licence to install TMVs, whereas tempering valves can be installed by any plumber
  • Servicing is needed more regularly for TMVs than tempering valves
  • TMVs respond to pressure variations quicker than tempering valves

Where can each be used?

Both TMVs and tempering valves can be used in varying environments including:


  • Hospitals
  • Schools
  • Nursing homes
  • Child care facilities and after school care
  • Respite centres
  • Aged care facilities
  • Hotels
  • Shopping centre bathroom facilities

TMVs are generally used in environments that include high-risk persons, such as children, the elderly and the sick, that require a lower water delivery temperature (usually 45°C or 113°C as a maximum).

Tempering valve

Tempering valves are generally used in residential homes for personal hygiene purposes, where water delivery is a maximum of 50°C (122°F)

Who installs TMVs and tempering valves?

A qualified plumber can install a tempering valve, however, a plumber with a TMV licence is the only one who can install a thermostatic mixing valve.

Tempering valves are required to be installed in the following situations (in accordance with the Plumbing Code of Australia):

  • When a new hot water system is installed
  • When a hot water system is relocated from one property to another
  • For any hot water system replacement

This means that all hot water system replacements should have a tempering valve installed. Some hot water system repairs do not require a tempering valve to be installed, but we suggest speaking to your plumber anyway to see if this is an option (it should be!).

Why use a TMV or tempering valve?

For two reasons – for safety and in accordance with the regulations. For the safety of those using a tap and to avoid injuries such as scalding, a tempering valve or TMV ensures the water being released from the faucet is not above 60°C (140°F) for tempering valves or 45°C (113°F) for TMVs. Additionally, in accordance with Australian regulations (National Plumbing and Drainage Standard AS/NZS 3500.4: 2003), various water installations are not permitted to deliver water at a temperature higher than 60°C/45°C for different fixtures.

Your hot water specialists across Brisbane

If you have any further questions regarding tempering valves, TMVs or other hot water arrangements, give Brisbane Plumbing and Drainage a call on 1300 616 203 and we would be happy to discuss your hot water needs.