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Tempering valves and TMVs are the devices responsible for ensuring that the water that comes out of your tap is safe and at the right temperature. But, what is the difference?

The mixing valve is a sliding component that is found in the tempering valve, ensuring the correct ratio of hot to cold water is being allowed to flow through. A tempering valve usually controls the temperature within ±3%.

Thermostatic mixing valves are required by law in the following locations, due to the possibility of high risk people being present (such as the elderly, sick or children):

1 1/4 Through 2 In Reduced Pressure Zone Total Repair Kit, Lead Free, Series 909M1. This is an original manufacturer repair product used within various divisions of the Watts Water Technology Company� (Ames, Febco, Watts)

A TMV mixes both hot and cold water together so it is a particular temperature (within 1℃ +/-) so it can be sent to different water outlets. The temperature is generally prearranged by a tradesperson or a qualified plumber, and the TMV element that responds to thermal activity alters the levels of hot and/or cold water to ensure the correct temperature.

According to Queensland legislation, hot water is to be heated to a minimum of 60°C to prevent the growth of bacteria such as Legionella. A tempering valve ensures that hot water flows from taps at a maximum temperature of 50°C.

Model 909 is a reduced pressure backflow assembly. Production began in 1979. The 3/4"-3" size body is constructed of bronze. In 2010 a LF909 model was produced that utilized a lead free bronze. The 2 1/2"-10" size check body is cast iron with a fused epoxy coating. The 2 1/2" and 3" were available in bronze and cast iron. Watts also has a hot water option available in the 3/4"-2" which is good up to 210° F. This is designated by the letters HW after the model number, e.g.: 909HW. The model M1 was introduced in 1989 in the 3/4"-2" and 4"-10" sizes. The 3/4"-2" size was changed by having the nipple between the body and the shutoff cast into the body instead of being a separate nipple. The repair parts on the 3/4"-2" 909 and 909M1 are the same. The 4"-6" size had a change on the relief valve body. The 909 design had a bronze relief valve body. In the 909M1 modification the relief body was changed to fused epoxy coated cast iron. The relief valve spring assembly was also changed. In the 8"-10" 909M1 sizes there was a change in the relief valve body. The relief valve utilizes the internal parts of the 4"-6" 909 unit. In the 909 M1 series the relief valve rubber repair parts will be the same in 4"-10". The check design will be similar to the 709. The check seats are replaceable and springs are contained when the covers are removed. The 2 1/2"-10" utilized an external relief valve sensing line and the relief valve body can be detached from the check body on these sizes. In 2010 a LF909 model was introduced in all sizes which replaced the internal leaded bronze parts with stainless steel and other lead free bronze materials. The rubber repair kit will fit both versions.

A tempering valve, which is also known as a hot water mixing valve or a hot water tempering valve, is either a 2-inlet or 3-inlet mixing valve which is adjustable and activated by temperature. It mixes both hot and cold water together to achieve a desired temperature, in order to regulate the temperature of hot water that flows from outlets in your home.

According to National Plumbing and Drainage Standard AS/NZS 3500.4: 2003, some water installations are not permitted to deliver water at a temperature higher than 50℃/45℃, which is why a TMV is installed – to assist with temperature regulation.

A tempering valve has a temperature sensitive element which focuses on adjusting the mix of hot/cold water depending on two factors:

https://www.health.qld.gov.au/public-health/industry-environment/environment-land-water/water/risk-management/plan/implement/monitoring-temperature

A thermostatic mixing valve, which is also known as a TMV, is a tool that combines hot and cold water together to maintain a specific water temperature when sending water through a faucet.

When you turn your hot water tap on, you expect hot water to flow out. Whether it is a shower, bath, kitchen sink or laundry basin, water at a particular temperature will always run from the faucets in your home or workplaces. But how does that occur?

https://www.business.qld.gov.au/industries/building-property-development/building-construction/laws-codes-standards/sustainable-housing

Although TMVs and tempering valves get regularly mixed up, they are actually two separate devices. They both mix hot and cold water together to achieve a specific water temperature, but there are a few notable differences:

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