AS/NZS 4032: Thermostatic Mixing Valves & Tempering Valves
- Ross Jones
- Jun 13, 2017
- 3 min read
Updated: May 17, 2023
Thermostatic Mixing Valves and Tempering Valves are temperature control devices installed within a Hot water delivery system to reduce the water down from 60 + degrees to either 45 degrees maximum for Hospitals and Aged Care via a Thermostatic Mixing Valve and maximum 50 degrees via a Tempering Valve for all other applications.
So why do we need them?
Every year around 5,800 people are admitted to hospital for hot liquid burns which totals 45% of all burns across Australia, as stated within the Public Health Association Australia, Injury Prevention Special Interest Group (SIG) "Hot water burns are preventable by fitting temperature reduction valves via hot water tempering devices such as Thermostatic Mixing Valves and Tempering Valves" - Link Below: but is also a legal requirement!
Water within your hot water unit must be stored at above 60 degrees to reduce the likelihood of Legionella and other bacteria growing within it - this is called maintaining pasteurization temperature within a stored hot water unit, this requirement was bought into law through an addition within the standard AS/NZS 3500 in 1998. So in doing this we brought the requirement for stored water into a temperature range that can burn very quickly:
Relative Contact Times for Full Thickness Burns to Occur:
50 degrees - 5 minutes for an adult or child.
55 degrees - 30 seconds for an adult and 7 seconds for a child.
60 degrees - 5 seconds for an adult and 1 second for a child.
70 degrees - 1 second for an adult and 0.5 seconds for a child.
Within the Australian Standards there are temperature management requirements under AS/NZS 3500, 4032, 4032.1, 4032.2 and 4032.3 and the Plumbing Code of Australia. Thermostatic mixing valves, when adjusted to an outlet temperature not exceeding 45°C, are intended for use in health care, aged, childcare, people with disabilities or any other similar at risk situations under AS/NZS 4032.1. Tempering Valves in all other suitable locations to deliver temperatures not exceeding 50 degrees.
We will concentrate on AS/NZS 4032.3 - 2004 "Water supply -Valves for the control of heated water supply temperatures Part 3: " as we can assume that you already have these types of devices installed as it is law.
Key Points from AS/NZS 4032.3 - 2004, Requirements for field testing, maintenance or replacement of thermostatic mixing valves, tempering valves and end of line temperature control devices.
Thermostatic Mixing Valves.
- Testing of thermostatic mixing valves required annually.
- In some cases risk analysis may require more frequent testing.
- Sufficient records of the maintenance and testing regime.
- Disinfection of the pipework from the Thermostatic Mixing Valve to the outlets
- Tested to the manufacturers instruction.
- Replacement of the temperature actuator every five years from commissioning or as per the manufacturers recommendations.
Tempering Valves: (yes they are required to be tested as well!)
- Basically all of the requirements under thermostatic mixing valve testing but full tempering valve replacement every 5 years as you cannot replace the temperature actuator within a tempering valve.
For all of the requirements you will need to purchase AS/NZS 4032 suite from SAI Global.
These are legal requirements and putting yourself and the people you care for at risk if it is not done.
For more information and or need someone to service your valves please feel free to contact us, we may be able to help, remember in some states you need licences issued by the state authority to service Thermostatic Mixing Valves, where there is no legal requirement in your state to hold a Thermostatic Mixing Valve testers licence ensure that the business doing your testing is a licensed and competent plumber, you cannot touch these valves without the correct licencing.
References:
AS/NZS 3500
AS/NZS 4032
AS/NZS 4032.1
AS/NZS 4032.2
AS/NZS 4032.3
SA Guidelines for the Control of Legionella - revised 2013
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Thermostatic Mixing Valves and Tempering Valves are used in hot water systems to control outlet temperatures. TMVs reduce water to a maximum https://www.contained.sydney/ of 45°C for hospitals and aged care, while tempering valves limit water to 50°C for other uses. This ensures safety and compliance, a technical standard sometimes explained alongside practical topics like The Pokies.