The Common Thermostatic Mixing Valve Problems to Know

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Last Updated on August 16, 2021 by Bonnie C. Welling

Imagine this. You have just spent the most hectic day of your life with work and everything lined up. And now finally you are in your space to have a heartful dinner, a nice warm shower, and get ready for bed. But the wish got spoiled thanks to your sudden realization inside the washroom, that the water is just cold and not comfortable at all. What could be the problem?

Well even if this is not the scene, the annoyance of cold water running your shower mood must be quite the same. One common reason behind this is a faulty thermostatic mixing valve. And that’s when knowing common thermostatic mixing valve problems help. Let’s talk a bit more to find out what’s all this about.

Thermostatic Mixing Valve Problems

Exploring Thermostatic Mixing Valve Problems & Solutions.

Let’s go through the possible causes that mean you are having a faulty thermostatic mixing valve issue.

The Temperature of Water Is Not Right.

The very obvious scene that we basically started this piece of writing with. If you notice that suddenly your well working hot water shower is switched to cold temperature without any reason, then it must be the valve having a problem.

Basically, what happens is that the valves fail to work on the regulation of temperature properly. And that’s why there’s a fluctuation of cold and hot temperatures.

And that is why sometimes instead of excess cold water you may also experience too hot water. The valve is not being able to provide the right temperature consistently.

The valve could be facing blockage. Or maybe it has shifted from the right position. Sometimes it’s because of the thermostatic element becoming damaged and not working. Having a damaged O-ring could also be the case. Another possible thing is having issues with water flow or pressure, and sometimes both.

The Normal Flow Of Water Is Missing.

Have you noticed the way the water comes out from the tap is somewhat different than usual? Such change in water flow is a very common indication of having a thermostatic mixing valve problem. Usually, the flow turns out less and the same goes for the pressure.

Running the water, if you can tell that it’s quite sluggish and slow, then definitely consider checking the TMV. In the worst case, you’ll end up having not more than just a trickle of water coming out of the tap.

And sometimes, the water pressure keeps on fluctuating, making it weird to take showers. Most probably there’s debris and scale gummed up on the parts of TMV. If it’s a pretty old one, then the possibility of corrosion is high as well. Sometimes due to improper fitting of this valve such issues take place.

Drips Or Leaks Noticeable.

One more common sign that you need to go for a thermostatic mixing valve repair is having water seeping out from parts. There could be water accumulated beneath on the floor as well. This is most probably due to a corrosion issue or even a faulty seal could be the reason.

For showers, you’ll notice drips once the TMV has worn out or have faults. The shutting-off mechanism could be failing due to improper placement of the TMV. And sometimes sits because of the cartridge or seal causing issues.

Thermostatic Mixing Valve Troubleshooting.

If you are having temperature being inconsistent issues, then you need to work on calibrating the valve properly. Follow the installation instructions to readjust the valve and the too hot/cold discharge should be solved.

The water flow issue can be solved by simply doing something about the fixture having too much pressure drop as well as checking debris that could be blocked in valves. You need to take measurements of supply pressures and adjust following the flowchart. Get rid of any blockage in the valve and clean it thoroughly.

For the water leaking issue, it needs a replacement of the thermostatic mixing valve. The high hot water causing pressure or freezing-related cracks are not repairable and it needs replacement.

How to Replace Thermostatic Mixing Valve?

How to Replace Thermostatic Mixing Valve?

You probably need to spend one or two hours to get the thing replaced. Anybody with a little bit of plumbing and soldering idea would be able to complete the task. Get a thermometer, a solder, hex wrench, adjustable wrench, and screwdriver.

  • The cold-water inlet isolating valve needs to be turned egg.
  • Then you must detach the pipe unions by unscrewing them.
  • Finally, get the valve out.
  • Follow the manufacturer-provided guideline to determine the valve’s positioning.
  • Then you want to connect the lines for water supply maintaining hot, cold, and mixed water outlines with heater.
  • On the valve, you want to solder all connections people and then place it in the gasket so that there’s zero damage. Some valve needs threading instead of soldering.
  • Fix the valve to its spot and use the wrench to score it in place.
  • Once the replacement is done, you want to turn on the cold-water supply and then the hot water line. See if there’s any sort of leaks.

How to Install Thermostatic Mixing Valve

Frequently Asked Questions

Can a thermostatic mixing valve go bad?

With constant usage, your holder model thermostatic mixing valves can get bad quite easily. And so, you must be prepared for a replacement sooner than later once it has served for quite a few years.

How long does a thermostatic mixing valve last?

It lasts a few years generally. Sometimes due to hard water or similar problems, the part wears out quickly. Typically expect it to work for around 5 years.

Overall Thoughts 

Now you know about a few of the common thermostatic mixing valve problems as well as ways to solve things out. The replacement is also simple and you should be able to do it yourself with a bit of know-how. Hopefully, this will be enough for you to solve the problem that you’re having with the valve.

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