How To: Moen Anti-Scald Shower Valve Adjustment

Moen is a household name known for its kitchen and bathroom products. From kitchen faucets to showerheads, Moen offers a variety of products to accommodate everyday needs, whether you’re washing dishes or taking a bath. 

Moen’s anti-scald facets allow users to regulate the temperature of their shower to avoid getting scalded (hence the name) by uncomfortably hot water. If you’re not sure how to adjust it, we’re here to help.

Why Should I Adjust My Anti-Scald Shower Valve?

The anti-scald feature in your shower essentially prevents you from getting burnt or scalded when you climb into the shower. The valve prevents water from getting too hot when you accidentally turn the handle too far. 

You might notice that you need to adjust the anti-scald valve throughout the year to meet your preferences. As the weather shifts throughout the seasons, you might need to manipulate the valve. For example, incoming cold water to your house varies in temperature (although the water heater remains at a stable temperature) between the summer and the winter, so you might need to adjust the settings. 

How Do you Adjust An Anti-Scald Valve In A Shower?

Moen offers a few different lines with temperature control. The company’s Posi-Temp line provides more precise control over the temperature range by using a pressure-balanced system. On the other hand, Moen’s Moentrol line features a similar application but isn’t as fine-tuned. 

Moen 2520 Posi-Temp Pressure Balancing Shower Rough-In Valve, 1/2-Inch CC Connection

You can probably find instructions specific to your model if you have the installation instructions. Otherwise, follow this guide. 

The mechanism works by preventing the hot water line from opening completely. This helps control the water temperature and prevents the user from accidentally getting scalded by piping hot water. 

By adjusting this mechanism, you can change the balance between hot and cold water, which affects the temperature range. It’s a relatively straightforward process that most homeowners have no issues completing. 

Here’s what you might need:

  • Philips screwdriver
  • Allen wrench
  • Flathead screwdriver
  • Towel

Although this process is simple enough, avoid making large adjustments. Tiny turns make significant changes, so this is a trial and error process. You might turn it too far, test the water, and find it too hot. Or, you might find the water doesn’t get hot enough. You’ll have to play with it until you find what works best for you. 

Turn Off The Water

Before you start, empty the cold water from the line. Open the faucet handle to the hottest position and allow the water to run until it’s piping hot. Once it reaches this point, turn off the water. 

Next, turn off the water to the shower faucet. In some cases, there might be a control panel in a closet nearby. However, if there isn’t, you might have to turn off the water to the entire house. After you turn off the water, drain the lines entirely by turning the faucet on and allowing it to run until the water stops flowing. 

Cover the drain with a towel, so you don’t lose any important parts. 

Remove The Handle

Once the water is off, and the lines are empty, your next step is to remove the handle from the faucet. The process varies based on the model – in some cases, there might be a set screw hidden under a decorative cap or in a recessed hole. 

Some set screws require a Philips screwdriver, while others require an Allen wrench. To remove the decorative cap (if applicable), you can use your fingernail or the edge of a flathead screwdriver. 

Remove the handle completely and set the screw and handle aside. 

Adjust The Settings

Generally, the valve body and cartridge stop ring will be visible once you remove the handle. If it isn’t, you might have to remove another screw with a Philips screwdriver. Once it’s out of the way, you should find a limit stop ring. 

You should be able to pull the stop ring out just enough to disengage the teeth holding it in place. Once you find it, you can adjust the temperature to your liking. 

To decrease the set temperature (if the water is too hot), turn the ring or knob counterclockwise. For warmer water (increase the set temperature), turn the ring or knob clockwise. 

Remember to make minor adjustments at a time – a small increment goes a long way. Once you make the adjustment, insert the stop ring back into the sleeve. 

Reassemble The Faucet

Moen T2151BN Brantford Posi-Temp Pressure Balancing Traditional Tub and Shower Valve Trim Kit Valve Required, Brushed Nickel

After you adjust the faucet, you need to reassemble the faucet. Start by reinstalling the outer piece and securing it with the set screw. Slide the handle back into place on the stem and secure it with the set screw. 

Next, turn the water supply back on and test your handiwork. Run the shower normally and test the temperature to ensure you like the adjustment. You may need to repeat the process a few times, making small changes each round to achieve the desired result.

In some cases, the entire cartridge in unused showers goes bad from the disuse. To prevent this from happening, run the shower for about five minutes per week. If the problem is already there, you might have to replace the entire cartridge to correct the issue. To remove the cartridge, you might need a cartridge puller. 

1 thought on “How To: Moen Anti-Scald Shower Valve Adjustment”

  1. I have to set my gas water heater to the “C” setting because the anti-scald valve reduces the temperature by about 20 degrees! If I set the thermostat to the “A” setting, the water temperature in the shower is under about 100 degrees. Br-r-r!

    The “C” setting makes a trickle of water flow out of the pressure relief valve. I replaced the valve, but the new one trickles also.

    I can’t get the screw out of the assembly because the previous owner stripped the Phillips head screw. I’ve tried every method to dry to unscrew it. Should I try drilling it out or is it time to call a plumber?


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