What Is a Water Heater Mixing Valve?

Is a steaming hot shower your favorite way to unwind? Even people who like their showers hot have their limits. So it's frustrating when the common factory setting on water heaters (140 degrees Fahrenheit) is higher than what you can handle. Sure, you can lower the setting on your water heater manually, but there's another option: a water heater mixing valve.

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Find out how it helps you get the temperature you prefer from your water every time without the risk of scalding.

What Is a Water Heater Temperature Mixing Valve?

A water heater mixing valve attaches to the outlet on the appliance to mix hot and cold water together. It prevents scalding by adding just the right amount of cold water to the hot water. That way, the water you get at your faucets is the right temperature for comfort and safety.

These tempering valves aren't universally required on all water heaters. In some areas, however, building codes require them in new construction. Whether required or not, it can be a beneficial addition to any water heater.

Another bonus is an increased amount of hot water available to you. Since the valve adds cold water to the hot water coming out of the tank, you use less hot water each time you turn on the faucet. It could help improve your hot water supply if you run out regularly.

How Does a Thermostatic Mixing Valve Work?

When you have a water heater mixing valve, you can keep your appliance set at 140 degrees. People who are immunocompromised may need the higher setting to prevent Legionella bacteria growth, for example.

You set a maximum temperature, such as the safer 120-degree setting, and the mixing valve ensures the water doesn't exceed that amount.

There are two types of these anti-scald valves: mechanical and electronic. A mechanical mixing valve includes a thermostat-like device that senses water temperature changes. It then adjusts how much hot and cold water go through the valve based on that temperature.

In an electronic mixing valve, temperature sensors and other electronic components help control the water temperature. Digital technology often makes this type of valve highly precise.

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If My Mixing Valve Is Bad, What Does That Mean for My Home?

Like any water heater part, the mixing valve can go bad eventually. It can become damaged, or buildup may affect the water flow. Its performance usually declines gradually, so a problem may not be immediately obvious. You can expect a valve to last for 5-6 years before it needs to be replaced.

If there's a problem with the hot water mixing valve, you might experience these issues:

• Higher-than-normal water temperatures

• Inconsistent water temperatures

• Overheating of the water tank

• Warm water from the cold tap or cold water from all taps

• Reduction in water flow

• Leaks around the valve

If the water heater temperature control valve stops working, you could be at risk of scalding hot water coming out of the taps. Unfortunately, you might not notice the increasing temperatures right away if the valve fails gradually. Having the valve repaired or replaced gets your plumbing system back on track and protects everyone in the household from burns caused by hot water.

An easy way to check the valve is to turn on the faucet closest to your water heater for a few minutes. Then, measure the water temperature. The valve is working correctly if the water temperature is close to the setting on the valve, which is often 120 degrees. If there's a significant difference, the valve may be malfunctioning.