Hot Water

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MT Plumbing

Hot Water

MT Plumbing is experienced in all hot water repairs and replacement.

We aim to restore hot water the same day; electric or gas.


Mains Pressure Hot Water System
A mains pressure hot water service is the most common older styles of hot water unit available and is still in use, be it gas or electric. It stores hot water in a tank and uses the pressure from the water main to push the hot water to the taps at the same pressure as the cold water.

Instantaneous or Continuous Hot Water System
A “continuous flow” or “instantaneous” hot water system has become more popular and is increasingly the preferred hot water system, as it heats water as it is used and does not store water so can never “run out”. These systems are suitable where there is a large or constant demand for hot water or where there are space limitations.

Contact the experienced team at MT Plumbing on (02) 9971 9738 to discuss your Hot Water System installation, repair or upgrade.


Legal requirements for storage and delivery of hot water

The Plumbing Code of Australia (PCA) requires that tempering valves be installed on all new homes or renovations & tank replacements.

To protect against the growth of Legionella bacteria (the cause of Legionnaires Disease), it is a legal requirement that stored hot water be kept at a minimum temperature of 60°C. This Australian Standard AS3500, 4.2 Clause 1.6. applies to all hot water systems with tanks, including solar and heat pumps.

A conflict arises where water at 60°C can cause serious burns in only one second. At 50°C, a serious burn wouldn’t typically happen until after 5 minutes.

For that reason, the Plumbing Code of Australia (PCA) requires that delivery temperature of hot water for personal hygiene use is not to exceed 50°C. The maximum temperature is 45°C for childhood centres, schools, nursing homes and similar facilities for young, aged, sick or disabled persons.

How do we meet the challenge of storing hot water at the legal temperature while delivering hot water at the safer temperature?

Tempering valves!

A tempering valve mixes hot and cold water to deliver hot water at a constant and safe temperature. Tempering valves have a temperature sensitive element which adjusts the mix, depending on the temperature of the incoming water flowing through the valve. The valve is designed to maintain a constant outlet temperature, reducing the risks of accidental scalding. MT Plumbing will adjust the valve to the required temperature.

When replacing an old hot water system it is a legal requirement to install a tempering valve to reduce the temperature to 50°C in bathrooms.

Kitchen and laundry applications are still permitted to bypass the tempering valve and use the hot water directly from a standard electric or gas hot water tank.

If you have an older hot water system, you may not have a tempering valve. MT Plumbing can install tempering valves to the existing hot water system.

The only exception to the legal requirement of installing tempering valves is for tankless continuous flow hot water systems. As these particular hot water systems have no tank in which Legionella bacteria can breed, they do not have to be set at 60°C and are typically factory pre-set to 50°C.