Thermostatic Valve Troubleshooting

If you are experiencing temperature fluctuations, or only hot, or cold water coming from your thermostatic valve, please use the below information to troubleshoot the issue.


Temperature fluctuations within thermostatic valves can happen for a few reasons.

  1. Thermostatic Cartridge needs cleaning or replacing.  Whether you are just installing your valve, or it has been installed for years, debris from the water lines can get into a valve cartridge and cause temperature fluctuations.    
  2. Check valves have accumulated debris from the water lines. The check valves are located on either side of the main valve and prevent backflow of water across water lines.  Debris can also enter these check valves and cause temperature fluctuations.
  3. Tankless water heater not supplying ample water flow to run the system.  Adjustments may need to be made.  Please check your manual on your water heater to determine how to adjust to meet the shower needs.
  4. Hot and Cold-water supply lines may be reversed (new installation).  If you experience only hot water, or only cold water upon first installing your thermostatic valve, it is a good indication that the hot and cold water lines are reversed. 

To determine if your faucet lines are installed incorrectly, you can perform this test to determine if cold water is coming to the correct side of the valve. With the main cover plate removed, you will be able to place a finger on the cold and hot inlet pipes of the faucet. The water will need to be on to conduct the following steps:

  1.  Lift the hand-held spray from its holder and point it in a direction away from the tester or the open door of the shower.
  2.  Turn on the hand-held function, then turn the temperature selector until hot water is flowing from the hand-held, being careful not to spray yourself.
  3.  Reach into the opening and place a finger on the RIGHT SIDE supply pipe. If the three-way diverter is the top knob, the right-side pipe should be cold. If this pipe is hot, the water lines are connected improperly and will need to be switched.

If the three-way diverter is located on the bottom and the RIGHT SIDE is cold, the valve has been installed upside down. Depending on the finished state of your wall, you can either flip the valve or have the water lines switched.



After cleaning the cartridge and re-installing it, you can set the temperature by following the instructions below:

Thermostatic valves incorporate a limiter that prevents the easy movement of the knob into the hot zone. This is a circular ring with one side being low and smooth while the other half is raised and ribbed. The limiter is arranged essentially north to south with the high side on the left

Please begin by turning on the water. 

Then turn the stem clockwise, using a pair of pliers, until you feel cold water. 

Now place the knob on the stem with the limit release button facing the floor. 

The next step is to rotate the knob counterclockwise until it makes contact with the limiter. You should feel warmer water. 

Once you depress the button, you should be able to bypass the limiter and the water temperature should increase as the knob travels farther counterclockwise

Fine adjustments can be made to the temperature by the rotating the stem clockwise or counterclockwise, but the knob must be set at one of the two points of the limiter.



If you notice that your shower isn’t dispersing hot or cold water, it may mean that your shower check valves are clogged. Watch our video to learn How to Clean Clogged Check Valves and restore the performance of your shower.


Your shower has a cartridge that regulates temperature, and if you have multiple shower components like a hand shower or body jets, your shower will have a diverter cartridge as well. Due to mineral deposits from your water and debris that can build up inside the cartridges, you may need to occasionally clean cartridges for best performance or to correct hard to turn handles. For step-by-step instructions visit ourHow to Clean a Clogged Shower Valve Cartridge  guide.


If your shower system is not diverting water, or you experience water dripping from the shower or hand shower, you may have debris or mineral buildup in your diverter or valve cartridge. A diverter cartridge is similar to a valve cartridge and can be cleaned. Use the following steps to clean your diverter or valve cartridge:

  1. Turn off the water supply to your shower
  2. Open the valve handles to release any water pressure.
  3. Turn handles back to the closed position.
  4. If your handles are attached with a set screw, use an Allen wrench to remove them. If they are held on with screws, use a screwdriver.
  5. Take off any decorative escutcheon exposing the cartridge.
  6. Using a wrench, unscrew the cartridge out of the valve body.
  7. Remove the cartridge and soak it in a 50/50 water and white vinegar solution for 30 minutes.
  8.  Turn the stem of the cartridge while soaking in the solution multiple times to loosen any remaining debris.
  9. This is a good opportunity to flush water through the lines while the cartridge is out.  We recommend opening the cold water side of the valve to avoid contact with hot water. Turn the valve just enough to let the water flow gently. Use a plastic tote or large bucket to catch the water or direct the water down.  
  10.  Turn the water supply back off.
  11.  Reinstall the cartridge, making sure not to overtighten the cartridge in the valve body.
  12.  Replace any escutcheon and the handle.
  13.  Turn your water back on and test the faucet flow.

For further assistance, please contact our customer relations team via live chat at or send us an email at


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