All how-to guides
  1. How-to guides
  2. Using your Cala's screen

Too hot or too cold? Adjust the water temperature at your taps

Use the steps on your Cala's screen to adjust the mixing valve and check the temperature at your taps.

Updated October 31, 2026

A mixing valve on your Cala sets the hottest water that reaches your taps. It is set at the factory to a safe temperature for most homes. If your hot water feels too hot or not hot enough, your Cala's screen walks you through adjusting the valve.

Start the adjustment

  1. On your Cala's screen, press any button to wake it. The Home screen appears.

  2. Press Down until SETTINGS is highlighted, then press Select.

  3. Press Down until TEMP CONTROL is highlighted, then press Select.

  4. Press Down until TOO HOT / TOO COLD is highlighted, then press Select. The MIXING VALVE OUTLET TEMPERATURE screen opens.

    MIXING VALVE OUTLET TEMPERATURE screen with ACCEPT 120°F (DEFAULT) highlighted and CHANGE TEMPERATURE below
    Keep the default or choose CHANGE TEMPERATURE.

  5. Press Down until CHANGE TEMPERATURE is highlighted, then press Select. The screen explains that your Cala needs to heat water first. (The other option keeps the valve as it was set at the factory.)

  6. Press Select to start heating. The screen shows APPROXIMATE TIME REMAINING and a number of minutes.

    Mixing valve heat-up screen showing APPROXIMATE TIME REMAINING 45 minutes and a Return to Home button
    Your Cala shows how long until the tank is hot.

  7. If you don't want to wait at the heater, press Select on Return to Home. Your Cala keeps heating.

  8. When the tank is hot, your Cala's screen shows IT'S TIME!. Read the warning, then press Select on Confirm and Proceed.

    IT'S TIME! screen with a warning, a QR code and a Confirm and Proceed button
    Read the warning before you press Select on Confirm and Proceed.

Step 1: Remove the central column

  1. Find the four screws that hold the central column on the front of your Cala. Each one only needs a quarter turn.

  2. Turn each screw a quarter turn counterclockwise with a screwdriver, then pull it out and set it aside.

  3. Pull the central column away from the front of your Cala and set it aside.

  4. On your Cala's screen, press Select on I've completed this step. The screen moves to Step 2.

Step 2: Adjust the mixing valve and check the temperature

The manual covers this step in "Adjusting The Thermostatic Mixing Valve (TMV)", page 36, including how to lock the setting (page 39).

  1. Find the mixing valve at the top of the plumbing inside your Cala. It has a numbered dial. The numbers show the dial's position only; they aren't temperatures.

  2. Turn the dial towards you to raise the temperature, or away from you to lower it. Move it one number at a time.

  3. Turn on a hot tap in your home and let it run until the temperature stops changing.

  4. Measure the water with your thermometer. Your Cala's screen also shows Detected Temperature:, the hottest water it measured leaving the heater.

    Step 2 screen showing Detected Temperature: 118°F with Save Temperature highlighted and Reset below
    Detected Temperature is the hottest water your Cala measured leaving the heater.

  5. If the temperature isn't right yet, highlight Reset and press Select to start a new reading. Then turn the dial one more number and measure again.

  6. When you're happy with the temperature, highlight Save Temperature and press Select. The screen moves to Step 3.

Step 3: Replace the central column

  1. Place the central column back over the plumbing, lining up its four holes with the four brackets on your Cala. The hot and cold water pipes line up with the cutouts in the sides of the column.

  2. Push each screw back through its hole and turn it a quarter turn clockwise while pushing in. It stops turning when it's secure. If a screw still wiggles, it isn't caught in the bracket; try again.

  3. On your Cala's screen, press Select on I've completed this step. The screen says Nice work! Your Mixing Valve is now set.

    Screen saying "Nice work! Your Mixing Valve is now set." with a Done button
    The mixing valve is set.

  4. Press Select on Done. Your Cala goes back to the Home screen.