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A Faulty Tempering Valve Element Can Keep Water Too Hot Or Cold

This small but mighty valve blends hot and cold water until it reaches the temperature setting on the dial. A small element or thermostat on the inside reads the temperature, and when it doesn't work properly, it will mix water incorrectly, leaving it too hot or too cold.

Check Your Tempering Valve Element

If the water in your home seems too hot or too cold, there may be an issue with the tempering valve on your boiler. You’ll want to be extra cautious when handling these heating elements to avoid burning yourself.

How to check your tempering valve element

  • Gently (don't wrap your whole hand around it) feel the water lines coming from the tankless coil. There are a few ways to identify the lines coming from your tankless coil. They are typically either round or rectangular, steel plated pipes on either the front or the top of your boiler. The cold water line will have a shut-off valve connected to it. The hot water line will have a tempering valve, which looks like a small control dial. Feel both lines. The hot water line should be hot to the touch, not just warm.


    CAUTION: Always be careful when working around pipes coming in or out of your water heater. They can be hot, and should be handled with care.

  • If the hot water lines feel hot, the next step is to check the tempering valve which is located on the hot water pipe near the boiler. The tempering valve is adjustable and should be set to 120℉ to give your water temperature a good balance between hot and safe.

  • The top part of the gauge will tell you the temperature of the boiler water. It should be between 160℉–210℉. The bottom part of the gauge will tell you the water pressure inside your boiler. It should be between 12–18 psi (pounds per square inch).

  • Now that you've seen the boiler settings, get an infrared thermometer (to avoid touching anything hot). Run your hot water on full, then measure the temperature of the hot water pipe coming out of the tankless coil. It should be close to the temperature setting you saw on the gauge. If it's not, there may have be issue with your tankless coil.

  • Next, check that your tempering valve is meeting its set temperature. To do this, run your tap on hot for a few minutes, then measure the temperature of the water. It should be close to 120℉. If it's too hot or too cold, your tempering valve isn't doing its job.

If this doesn't seem to be the problem and you still don't have hot water, consider other potential reasons.

What to Do if Your Tempering Valve Element Is Faulty

If your water is still too hot or too cold, it's time for a professional to come fix the tempering valve element on your boiler.

NOTE: This content is for informational purposes only, and HomeX and its affiliates disclaim all liability related to it. If you decide to perform any tasks based on this information, you assume all risks, including the risk of loss or damage to property or personal injury.

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