How to Adjust the Temperature on a Moen Anti-Scald Shower Faucet

Moen is well known for its high-quality, affordable faucets for the kitchen and bath. The company offers a line of anti-scald faucets that allow the user to set and control the temperature of the shower to avoid accidentally turning water to uncomfortably hot temperature.

As the weather changes throughout the year, it may be necessary to change the settings on these anti-scald faucets. Although a hot water heater stays at a stable temperature, the incoming cold water to the house varies in temperature as seasons change, meaning these settings may have to be adjusted for winter and summer usage.

The Moen Posi-Temp line for showers uses a pressure-balanced system to specifically control the temperature range; their Moentrol line has a similar application but lacks the precise control of the Posi-Temp.

These controls work by using (different) mechanisms to prevent the full opening of the hot water line. This protects the user from accidentally reaching uncomfortable and potentially dangerous hot temperatures in the shower.

Adjusting this mechanism changes the balance of hot and cold water, which adjusts the water temperatures accessible by the Moen anti-scald faucet. It isn't necessarily difficult to adjust this stop, although details vary, depending on the model of faucet in the shower.

First, purge the line of cold water. Open the Moen faucet handle to the hottest position and allow the water to run until hot. Shut off the water to the faucet using the supply valves; these are usually behind the shower wall.

If these aren't accessible, you may need to shut off water to the entire bathroom. Figure out the most appropriate access point and be sure the water is shut off by opening the faucet to let the line completely drain.

Next, remove the handle from the faucet. Depending on the model, the set screw for the handle may be hidden under a decorative cap; some set screws need a Phillips screwdriver, while others require an Allen wrench. Remove the set screw and pull the handle off the wall.

With most models, the cartridge stop ring will be visible. Sometimes there is another screw that you will need to remove with a Phillips screwdriver. Beneath this you should find the limit stop ring, which you can pull out just enough to disengage with the teeth beneath.

To decrease the set temperature (for cooler water), turn the ring or knob counterclockwise. Small increments can make a big change, so turn less than a quarter-turn at first before checking the water temperature.

To increase the set temperature (for warmer water), turn the ring or knob clockwise a small increment. Insert the stop piece back into the sleeve.

Reinstall the outer piece and tighten the set screw. Slide the handle back onto the stem and secure its set screw in place. Turn the water supply back on, run the shower as normal and then test the temperature to make sure the adjustment is sufficient. Repeat steps as necessary until you find the perfect temperature range.

If the shower hasn't been used in a while and you're seeing only hot or only cold water, the entire cartridge may need to be replaced as the inner pieces can get stuck during nonuse. Try to run the shower at least once a week for at least five minutes to prevent this from happening.