Hot water tempering valves and TMVs (thermostatic mixing valves) are often confused with each other because they serve a similar purpose. Both valves are designed to control the temperature of the hot water that flows from the taps inside a home.

Both hot water tempering valves and thermostatic mixing valves mix cold and hot water together to ensure a preset hot water temperature that comes out of the hot water taps.

How A Hot Water Tempering Valve Works

A hot water tempering valve also commonly referred to as a hot water mixing valve, is temperature activated and fully adjustable to produce a hot water output of between 40 to 50 degrees Celsius. 

A hot water tempering valve blends cold water with the hot water stored in the hot water unit so that the hot water that comes out of the taps is at a safe temperature. For most hot water installations this would be around 40 to 50 degrees Celsius.

At the same time, the tempering valve ensures that the hot water stored inside the hot water system sits at a temperature no less than 60 degrees Celsius in order to eliminate any bacteria from the storage tank.

How A Thermostatic Mixing Valve Works

A thermostatic mixing valve operates in response to the thermal activity of the water. It will mix cold water with hot water before the hot water is sent through the taps into the home.

The desired temperature of the hot water output is set by a qualified plumber during installation. The TMV has an element that responds to the temperature of the water and mixes cold water with the hot water so that the hot water that comes out of the taps at a maximum temperature of 50 degrees Celsius.

What Are The Primary Differences Between Tempering Valves and TMVs?

While both tempering valves and TMVs control the temperature of the heated water coming out of the taps, there are some notable differences between the two.

TMVs are more accurate in their temperature control and respond faster to water temperature changes. While hot water tempering valves are accurate to 3 degrees Celsius + or -, TMVs are accurate to 1 degrees Celsius + or -.

For this reason, the plumbing code requires that TMVs are installed in high risk facilities such as hospitals, aged care facilities, nursing homes, schools, childcare centres, hotels, respite centres and shopping centres.

This ensures that people who are more at risk from scalding by hot water, such as young children and the elderly, are fully protected.

Here are some other notable differences between hot water tempering valves and TMVs:

• TMVs cost more initially
• Only a licensed plumber who has a TMV licence is allowed to install a TMV valve
• TMVs last much longer than hot water tempering valves
• It’s more common to repair TMVs 
• It’s far more common to replace tempering valves rather than repair them

What Are The Common Uses Of Tempering Valves As Opposed To TMVs?

Hot water tempering valves are commonly installed on every new household hot water service or during a hot water repair because they are cheaper to purchase and can be installed by any licensed plumber. On the other hand, the plumber needs a special licence to install a TMV.

Tempering valves are suitable for any gas hot water system or any electric hot water system in residential premises. 

The plumber can also easily replace the tempering valve once it gets to the end of its useful life. According to Australian Standard Regulations, tempering valves should be tested every 12 months to ensure they’re in good working order. 

It’s more common for TMVs to be installed in public buildings as they are more expensive but have a higher degree of accuracy. Plus, they tend to last longer than tempering valves. In general, the recommendation is to replace the O-rings and thermostats every 5 years.

Purchase Your Hot Water Tempering Valves From Forge Plumbing

At Forge Plumbing, we stock both the standard (yellow cap) and high performance (orange cap) hot water tempering valves for all residential plumbing installations. We have both tempering valves in two sizes - 15mm and 20mm.

If you’re after quality hot water tempering valves for your plumbing service, take advantage of our free shipping on every order and our free returns policy.

For any questions or advice about the wide range of plumbing supplies we stock, feel free to contact our friendly customer service team who will be more than happy to help you.