Tempering Valve Maintenance And Replacement On Your Hot Water System

When there is no hot water the tempering valve could be a good place to start.

Often the problem can be fixed by a plumber. We will check over and service your complete system while we are changing the tempering valve.



The tempering valve is usually located at the hot water system. It’s purpose is to pre-mix very hot water (60 degrees Celsius +) from the hot water system with cold water to a controlled and safe temperature which will not cause accidental scalding.

Because the mechanics of the tempering valve are vulnerable to debris carried in the water supply the valve is fitted with fine mesh filters on the hot and cold water inlets of the valve.

Usually what happens is the hot water inlet filter of the tempering valve becomes blocked by debris which means there is no hot water or the supply of hot water is limited.

To protect people from accidental scalding the Plumbing Code of Australia has made mandatory that the maximum allowable temperature at bathroom fixtures is not greater than 50 degrees Celsius.

Because at 60 degrees Celsius hot water can cause a serious burn in a second.

Kitchen and laundry fixtures are not required to be temperature regulated.

After installing a hot water system the plumber is required to check and certify the tempering valve is set correctly, delivering hot water temperature to bathroom fixtures at a temperature not greater than 50 degrees Celsius.

Note regarding solar hot water installations: even though there is no requirement (yet) to temper water to kitchen and laundry fixtures it is recommended. This is because of the extremely high temperatures solar hot water systems can produce e.g. 80 degrees Celsius +.

Plumbers will generally position the tempering valve close to the outlet of the hot water system, which means that the entire house has tempered hot water.

But if anything goes wrong with the tempering valve it will effect all the hot water in your home.

To identify the rating of the tempering valve the cap will be colour coded:

  • Electric hot water heater – blue
  • Solar hot water Tempering Valves – orange
  • Gas – green
  • Gravity feed low pressure – black

Preventative measures can be taken to minimise risk of the tempering valve filters becoming fouled.

  • Before connecting the hot water system the cold water supply pipe needs to be flushed to ensure that no swarf – copper filings, plumbers tape etc will enter the system and foul the filters or the mechanism in the tempering valve.
  • Most manufacturers will recommend you replace the tempering valve every 4 to 5 years.

So if the hot water is not what it should be contact us at www.solarhotwaterrepairsqueensland.com.au for an inspection and clean to be sure the hot water supply can pass the tempering valve and deliver a hot shower.