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Firstly, what is the importance of a tempering valve?
Hot water can very quickly cause scalding and burns which can be serious and painful, particularly for children. Water at the ‘required’ 60°C can cause a third-degree burn to the skin in less than 5 seconds for an adult and only 1 second for a child.
A tempering valve will reduce the risk of receiving a third-degree burn to the skin. Having the water at a temperature of 50°C, reduces the chance of a serious burn or scald substantially. Water at 49°C will take up to 5 minutes for a serious burn or scald to occur.
So, what is a tempering valve?
A tempering valve (also known as a mixing valve) is a safety device designed to control hot water temperature. The three-way mixing valve consists of 3 connections:
Hot water inlet
Cold water Inlet
Outlet (mixed hot and cold water)
The flow and temperature of the mixed water is kept consistent by a thermostatic element which is submerged in the water. It functions by expanding and contracting (in response to temperature changes) to adjust the flow into each inlet valve. This element is accurate to within 3°C of the set temperature.
Why is the water in a hot water system ‘required’ to be kept at a minimum of 60°C if this is a dangerous temperature?
The Plumbing Code of Australia (PCA) tempering valve requirements are, as per the Australian Standard AS3500.4.2 Clause 1.6, a hot water system must be set at a minimum of 60°C to avoid Legionnaires Disease (a harmful bacteria to humans) growing in the system.
Fortunately, tempering valves were introduced to reduce the risk of serious burns and scalds. The Plumbing Code of Australia (PCA) tempering valve requirements are:
in a bathroom, the maximum hot water temperature, from the tap, is not to exceed 50°C (bypassing the hot water tempering valve is permitted for kitchens and laundries); and
in childhood centres, primary and secondary schools, hospitals, nursing homes and similar facilities for the young, aged, sick or disabled persons, the maximum hot water temperature, from the tap, is not to exceed 45°C.
Do all hot water systems require a tempering valve?
All hot water systems with tanks, including solar and heat pumps, require a tempering valve. A tankless continuous flow hot water system (whether natural gas or LPG) does not require a tempering valve.
Are you allowed to adjust a tempering valve?
It is a legal requirement that the water temperature can only be set to a maximum of 50°C. If you would like for the temperature to be set lower than 50°C, a licensed plumber is required to carry this out for you.
How long do tempering valves last?
It is recommended by the manufacturers of tempering valves that they be changed every 5 years (if maintained and serviced regularly). An annual service by a qualified plumber involves:
removing the build-up of scale inside the valve (one of the main causes of tempering valve failure)
cleaning line strainers and filters
flushing the system
This routine service of a tempering valve can be combined with the routine service of your hot water system, thus keeping both working properly and efficiently (and potentially extending the life of both).
How do you know if a tempering valve is not working properly or failed?
Most tempering valves have a thermal shut-off feature that closes the hot and cold inlet valves should a fault occur. Whether your tempering valve has a thermal shut-off feature or not, signs will be:
loss of hot water
lower hot water temperature
reduced hot water pressure
If you find yourself with a tempering valve that is not working properly or failed (or you do not have a tempering valve), Howzat Plumbing offer a 24/7 emergency service – please don’t hesitate to contact us. We are based in Chermside, however we have team members located throughout the Brisbane northside and southside, the Moreton Bay and Samford Valley regions, Brisbane's East, Bayside, Western suburbs, CBD and inner-city who will be able to head to your property as a matter of urgency.
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