In hot water systems, the valves that control pressure, temperature, and flow are vital for safety but often overlooked. Most Brisbane homeowners focus on price, size, and appearance when shopping for a new hot water system, rarely considering the crucial role hot water valves play in keeping the entire system safe.

Quality Australian hot water valves installed on residential hot water system

What is a Hot Water Valve?

A relatively straightforward mechanism, the hot water valve, legally required on hot water systems in Australia, is not an optional extra. They are mandated safety devices that stop your hot water system from over-pressurising, exploding, pushing hot water back into the drinking-water mains or causing serious burns.

Pressure Limiting Valve (PLV)

Brisbane’s mains pressure can exceed 800 kPa. A pressure limiting valve, also known as a pressure reduction valve, reduces pressure to a safe 350–500 kPa. An over-pressurised cylinder can result in a ruptured tank and significant water damage.

Keep an eye out for constant dripping from the overflow pipe or unusually high water bills. These are telltale signs of a failing PLV.

Water outlets directed into drain from hot water valves

Cold Water Expansion Valve (CWE)

In addition to the PLV, a CWE, which sits on the inlet of the tank, is another mandatory addition to any hot water unit. It relieves excess pressure caused when water heats and expands inside the tank. When not fully functional, excess pressure can result in significant damage to the unit itself.

Water dripping from the drain line every time the system heats could be a sign that it’s time for a hot water system service.

Tempering Valve

Also known as a temperature control valve, a tempering valve is what cleverly blends hot water with cold to ensure a safe water temperature of 50 °C (or lower) in your home. As a minimum, this valve should be replaced every 5 years, or its filters cleaned, and temperature reset more regularly.

You’ll be alerted to a faulty temperature valve if you experience significant water temperature changes in the shower, scalding hot to freezing cold or inconsistent temperature swings.

Duo Valve

The valve under the tank that isolates the system and stops hot water from flowing back into the mains is called a duo valve. When the duo valve stops functioning as it should, contaminated water can get pushed back into drinking lines.

If you notice that this valve is stiff or impossible to turn, leaking when closed, or you can’t fully shut off the water for maintenance, it’s time to get it looked at.

Gas Isolation Valve

Also known as a gas cock, the gas isolation valve works to completely shut off the gas supply to your unit. Essential for maintenance or a gas leak, these valves rarely fail, but when they do, it’s serious.

If the gas isolation valve is stiff to turn or you notice green corrosion around pipes, call a licensed gas fitter immediately.

Hot Water Valve Replacement and Servicing

The installation and maintenance of your hot water system and hot water valves are subject to plumbing regulations and standards, resulting in penalties for non-compliance. While these penalties apply to the installer, not the homeowner, non-compliant work can render product warranties void and compromise your home insurance.

Always choose a qualified hot water technician to carry out any preventative maintenance or repairs. Salmon Plumbing is Brisbane’s leading expert when it comes to hot water valves. The team are fully insured, QBCC licensed plumbers and gasfitters.

Opting for a cheaper, knock-off imported valve when a replacement is needed might save you money upfront, but poor-quality valves are likely to fail sooner, leading to costly premature replacement. Australian manufacturers build valves from brass or stainless steel. They are high-quality and typically last much longer than a cheap import.

Even high-quality hot water valves will progressively fatigue over time. These components may be small, but don’t underestimate their importance! Routine hot water servicing includes the replacement of hot water valves and other critical components so that your hot water system performs at peak efficiency.

Protect Your Hot Water System With Professional Servicing

To book professional hot water servicing with Salmon Plumbing, please get in touch.