How to Adjust the Temperature on a Moen Shower

Moen makes anti-scald shower faucets that allow you to manually set the maximum temperature of the water. This is a great safety feature, especially for households with children who might turn the temperature too high and hurt themselves.

However, Moen shower faucets may occasionally require adjustments. As the seasons change and the groundwater changes temperatures or as you adjust your hot water heater, your Moen shower faucet may also require calibration.

The most common issue with Moen shower faucets is that the water coming out is not hot enough. However, the same principles apply whether you need to increase or decrease the maximum temperature.

Moen explains that there are a number of typical causes for the temperature not being hot enough. These include hot water not being supplied to the valve, a balancing spool being stuck or the Moen shower faucet unit not being calibrated to allow full hot water. The maximum recommended temperature for hot water is 120 degrees Fahrenheit, though some municipalities mandate lower maximum temperatures of 115 or 105 F.

You can measure the temperature of the water coming out of the faucet by turning it to full hot, waiting two to three minutes for it to reach maximum temperature and holding a thermometer under the running water. If the water is below the desired temperature, begin troubleshooting.

First, check that sufficient hot water is being fed to the Moen shower faucet unit. There should be a panel on the opposite side of the wall the shower is installed on.

Open the panel and locate the hot- and cold-water valves. Make sure both valves are all the way open. Also verify that your water heater is working properly and is set to a high enough temperature.

If that does not alleviate the issue, the next steps depend on the model of your Moen shower faucet. Moen explains that you should identify the model before you proceed. You will need to disassemble the faucet handle and check inside the unit. First, shut off the water of the shower and turn the shower on all the way to drain any residual water.

Once the water is off, check the rotation of the faucet handle. It should rotate all the way counterclockwise to the 9 o'clock position. Note how far it rotates; then remove the handle.

Most models will have a set screw underneath the handle that can be unscrewed with an Allen wrench. Some models will have the screw hidden behind a decorative cap that needs to be removed. Use the Allen wrench to unscrew the screw and set the faucet handle and screw aside — be sure not to lose the screw.

If the handle did not rotate all the way, the temperature limit stop needs to be repositioned. Unscrew the screw holding it to the top of the cartridge sleeve and pull the ring out far enough that the teeth of the ring disengage.

This temperature limit stop can be adjusted clockwise to increase the temperature or counterclockwise to decrease the temperature. Reinsert the ring into the sleeve, secure the screw again, replace the handle, and test the rotation and temperature again.

If this does not address the issue, you may need to replace a part. For Posi-Temp models, if the water pressure decreases when going from cold to hot, the 1222 cartridge may need to be replaced. For Moentrol models, inspect the 1423 balancing spool. This will look similar to a brass-colored flathead screw the size of a quarter and will be positioned on the front of the valve body, either above or to the right of the cartridge.

Unscrew the balancing spool and check if the spool inside this piece moves freely. If it does not, the 1423 balancing spool will need to be replaced. If the balancing spool is good and adjusting the rotation of the faucet handle did not address the issue, the 1225 cartridge may need to be replaced.

For 3/4-inch ExactTemp models, the temperature override button needs to be pressed to enable the handle to rotate further and get temperatures above 105 F. If that is working correctly, verify that the stops are opened. These are located on the inlets of the valve and look like small flathead screws. Make sure these are screwed all the way counterclockwise (turning them all the way clockwise will turn the water off).

For ioDigital models, check the valve inlet screens for debris. You can also adjust the maximum temperature with a blue dial on the valve labeled "Max Temp Adjustment." This can be rotated clockwise to increase the maximum temperature. Remember, you can always consult the manual that came with your Moen unit for further directions or contact Moen customer support.