Thermostatic Mixing Valves

When you turn the hot water on in your home or work it's an expectation hot water will automatically flow. But have you ever wondered what temperature the water should be?

Generally, the water coming out of the tap should be at a domestic property should around 50 degrees to avoid scalding, and if your water is supplied through a storage hot water system the water in the heater should be kept at a minimum of 60 degrees to avoid legionella (a bacterium that thrives in a moist environment ) from growing. This bacterium causes Legionnaires disease which is a type of pneumonia and can cause the elderly or people with a weakened immune system to become particularly ill.

Thermostatic mixing valves are fitted for safety and are regulated under the National Plumbing and Drainage Standard AS/NZS 3500.4: 2003, various water installations cannot deliver water in excess of 45 degrees to prevent people getting scalded, generally installed in disabled facilities, hospitals, schools, public sporting complexes or any hot water outlet accessible by the public.

A similar valve is a tempering valve which is more commonly used in residential properties. This is also temperature sensitive to within 3 degrees accuracy and is a mixing valve that combines the hot water from the hot water system with cold water to deliver water through your tap at a moderated temperature usually 50 degrees.

Tempering valves are required to be fitted in the following situations as per the Plumbing Code in Australia:

• When a new Hot Water Unit is Installed
• When a Hot Water System is relocated
• For any Hot Water Unit Replacement