Why Is My Hot Water Only Lukewarm? It Could Be a Faulty Tempering Valve

If your hot water is only lukewarm, it's easy to assume your hot water system has reached the end of its life. However, that's not always the case.

At Intec Plumbing & Gas, we recently attended a home where the owner believed their heat pump hot water system needed replacing because the water wasn't getting hot enough. After carrying out a thorough inspection, we found the heat pump was operating correctly. The real problem was a faulty tempering valve.

Replacing the tempering valve restored the hot water temperature, saving the customer from replacing a hot water system that was still in good working order.

What Does a Tempering Valve Do?

A tempering valve is an important safety device installed on many hot water systems. Its purpose is to mix hot water from the storage tank with cold water before it reaches your taps, delivering water at a safe temperature while helping reduce the risk of scalding.

Over time, tempering valves can wear out or become faulty, affecting the temperature of the water throughout your home.

Examples of Tempering Valves We've Replaced

Below are a few examples of tempering valves we've replaced on different hot water systems throughout Perth.

While every installation is different, tempering valves are commonly installed on the outlet pipe of storage hot water systems, including heat pump, electric storage, gas storage and solar hot water systems.

If your hot water is only lukewarm or the temperature varies throughout the day, the tempering valve may be contributing to the problem.

Faulty tempering valve fitted to a heat pump hot water system. This valve was causing the customer to experience lukewarm hot water throughout the home.

Replacement tempering valve installed on a storage hot water system. After replacing the faulty valve and testing the system, normal hot water temperature was restored.

Another example of a tempering valve installation. The location of the valve can vary depending on the type of hot water system and the plumbing layout, but it is commonly installed on the hot water outlet pipe near the storage tank.

Common Signs of a Faulty Tempering Valve

A faulty tempering valve may cause:

• Lukewarm hot water at every tap.

• Hot water that never reaches the correct temperature.

• Inconsistent water temperatures.

• Reduced hot water performance even though the system is still heating correctly.

These symptoms can often be mistaken for a failed hot water system.

How We Diagnosed the Problem

When we inspected this heat pump hot water system, we carried out a series of checks to determine whether the unit itself was operating correctly.

Our testing confirmed the heat pump was producing hot water as designed. The issue was traced to the tempering valve, which was allowing too much cold water to mix with the hot water before it entered the home's plumbing system.

After replacing the faulty tempering valve and testing the installation, the hot water temperature returned to normal.

Why Accurate Diagnosis Matters

Not every hot water problem requires a complete system replacement.

Correctly diagnosing the fault can often identify a failed component that can be repaired, helping homeowners avoid unnecessary replacement costs.

At Intec Plumbing & Gas, we take the time to identify the cause of the problem before recommending repairs or replacement, ensuring our customers receive the most suitable solution for their home.

Need Help With Lukewarm Hot Water?

If your hot water isn't getting hot enough, don't assume you need a new hot water system.

Whether the problem is a faulty tempering valve or your hot water system has reached the end of its service life, Intec Plumbing & Gas can diagnose the issue and recommend the right solution.

Contact us today for professional hot water repairs and hot water system replacements across Perth.