The PTR pressure temperature relief valve regulates the pressure caused by water volume expansions during normal heating cycles in a hot water service. The PTR valve relieves this increase in pressure by a controlled water dripping into a drain line typically of 2 to 5 litres per day depending on the hot water usage.
The PTR pressure temperature relief valve also acts as a mechanical protection device for the hot water services. In rare occasions of a faulty thermostat or heating element, the hot water service can overheat, building a dangerously high pressure and temperature inside. When this pressure or temperature exceeds the PTR valve's rating, it will dump hundreds of litres of water all at once as an emergency pressure relief. Usually a large puddle of water will be observed around the hot water services on the ground during this emergency water dumping. The PTR valve usually has a KW rating, which describes this emergency water dumping ability in terms the heat dissipating power. A larger PTR valve will usually have a larger KW rating and this KW rating is specified by local plumbing rules, especially in large commercial hot water systems.
A functioning PTR valve is a requirement by law in Australia for safety as per explained above. A typical sign for a faulty PTR valve is when there is a large amount of water leakage in a stream, rather than a controlled dripping. The worn out or leaking PTR valve must be replaced immediately.
An optional PTR insulation jacket is available which can reduce the heat loss and improve the hot water services' overall thermal efficiency.
