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Oct 19, 2023 10:00:00 AM by Logan Donahue

Should I Install a Water Heater Mixing Valve?

A water heater mixing valve is an essential component of a hot water system that helps regulate the temperature of the water being delivered to various outlets in your home. This valve is typically installed near the water heater and is responsible for blending hot water from the heater with cold water to achieve the desired temperature.

Understanding Water Heating Mixing Valves


How does a water heater mixing valve work?

It operates on a simple yet effective principle. When you turn on a hot water faucet, the valve senses the temperature of the water coming out and adjusts the ratio of hot and cold water accordingly. This ensures that the water delivered to your taps or shower is at a safe and comfortable temperature, helping to prevent scalding accidents.

How much capacity does a mixing valve add to a water heater?

A mixing valve also adds an incredible amount of capacity to your water heater. By blending hot water with cold water, the overall volume of available hot water increases significantly. Adding a water heater mixing valve will give you at least 25% more hot water. HVAC professionals estimate that a mixing valve could even increase your capacity by up to 50%. This means you can enjoy longer showers, fill up your bathtub, or run multiple hot water appliances simultaneously without running out of hot water. It's a game-changer, especially for larger households or those with high hot water demands.

Purpose of Mixing Values


When talking about safety, there are really two issues to consider: serious burns and Legionnaires Disease.
Serious Burns
Water heater manufacturers typically set their units to a safe temperature of 120°F, which prevents the risk of burns and disease. At this temperature, it would take more than five minutes for a serious burn to occur. However, even a slight increase in temperature by 10° can result in a serious burn in just about 30 seconds. Hot water at 140°F can cause harm in less than five seconds, which is a significant risk, especially for children and the elderly who are more susceptible to scalding. Valves are mandatory for combi boilers that have summer/winter modes to prevent scalding because these systems run at higher temperatures.
Legionnaires disease
By installing a mixing valve, you can raise the water temperature within the tank. The valve will mix water at a lower temperature to prevent scalding. This is crucial because Legionella bacteria can lead to Legionnaires disease, a severe form of pneumonia that spreads through water droplets when showering or being exposed to hot water mist. Therefore, it is important to set water heaters to at least 120°F to prevent the growth of Legionella bacteria. Using a hot water heater mixing valve allows you to maintain a safe temperature within the tank while reducing the output at the faucet to a level that is safe and won't cause burns.


In conclusion, a water heater mixing valve is a valuable component of any hot water system. Its ability to regulate water temperature, increase capacity, and ensure safety makes it a must-have for every home. So, if you're looking for a solution to enjoy ample hot water without compromising on safety, installing a mixing valve is the way to go. Stay comfortable while staying safe!
Contact ECI Comfort

If you live in the Delaware Valley/Greater Philadelphia area and would like to find comfort within your home, visit our website or give us a call at 215 - 245 - 3200 to learn more.

This entry was posted in Temperature Regulation, Safety, Tankless Water Heater, Water Heater

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