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Regular PTR Valve Checks And Replacement Of Old Hot Water Expansion Valves

  • by Mat Briggs
  • Monday, April 11, 2016

It is easy to forget just how much we depend on our hot water systems. Showering, cooking, washing up. Most people only appreciate just how important their hot water tank is when it fails. Murphy's Law dictates that this usually happens in a very spectacular fashion, in the earliest hours of a very cold Sunday morning when every plumber in your neighbourhood is on holidays...

Hot water systems may seem a bit complicated and mysterious but like all other parts of your home they'll benefit greatly from a bit of routine maintenance. This is particularly the case with hot water tank systems - because continuous flow hot water systems don't store hot water and are unlikely to build up any pressure. They require much less attention.

Effective maintenance for hot water tank systems is pretty easy and can double or triple the effective lifespan of your hot water system. To maintain your system, there are two main things you'll need to consider:

  • the sacrificial anode, and
  • the temperature and pressure relief valve (PTR valve for short).

How to test your temperature and pressure relief (PTR) valve

Flushing and testing a PTR valve is relatively straightforward and something you can do yourself. If the valve is already leaking water through the outlet pipe it will need to be replaced. Testing the valve involves expelling some extremely hot water. So if you are going to test your PTR valve ensure that you are wearing long pants, covered shoes and gloves:

  • Check to ensure that the area beneath the outlet pipe from the PTR valve is clear and free from obstruction. Make sure you are standing as far away as possible from the end of the pipe.
  • Gently lift the handle on the PTR valve. If it is stuck don't force it. If it doesn't want to move you will need to replace it. As you lift the valve handle very hot water should flow out from the end of the outlet pipe.
  • Gently return the valve to its closed position. The flow of water should stop. If it doesn't this likely indicates that the valve isn't working reliably and needs to be replaced.

How often should temperature and pressure relief (PTR) valves be tested and replaced?

Ideally, you should refer to the manufacturer's advice on how often to test your PTR valve - although as a rule of thumb this is normally something you should do once every six months.

PTR valves have a limited rated service life too and need to be replaced periodically. Again, how often they need to be replaced will depend on what is recommended by the manufacturer. In many cases this is something you will need to do once every two to three years.

Why is the PTR (Pressure Temperature & Relief Valve) leaking so much?

Located on the side of the water tank, the PTR valve is an essential component of your solar hot water system. The PTR valve is designed to allow 3-5% of your total tank volume to discharge during heating. This allows for hot water expansion and also ensures that your system continues to run safely. If you notice that your PTR valve is leaking excessively during the day and night contact us www.solarhotwaterrepairsqld.com.au to have it checked as it may be faulty.


This is caused hot water tank doming it is caused by not replacing the PTR valve.