Many modern shower valves are equipped with an antiscald feature restricting the hot water flow to a predetermined level through the showerhead. The antiscald adjustment does not alter the water temperature flowing through your pipes, but limits the amount of hot water mixing with cold water passing through the showerhead. This safety feature helps protect individuals from injury, especially children who might turn the valve control too high. Adjust the anti-scald feature takes only a few minutes using basic tools.
Pry the cap off handle's center exposing the screw underneath. If your shower knob does not have a screw in the handle, locate the hollow-set screw in the side of the control where the handle attaches to the valve.
Take out the center screw with a screwdriver or use an Allen wrench loosening a hollow-set screw in the side. Pull the handle off and set aside.
Pull the round, metal plate on the valve assembly's end toward you in the open, locked position. The antiscald adjustment knob is behind this plate and fits into a series of serrated notches.
Pull the antiscald adjustment knob forward, using needle-nose pliers if necessary, and turn it counterclockwise lowering the hot water mix. This reduces the maximum temperature of the water than flows through the showerhead. Turning the adjustment knob clockwise increases the water's maximum temperature. Each notch increases or decreases hot water flow to produce an overall temperature change of 4 to 20 degrees, depending on the faucet model.
Push the adjustment knob inward and press the round plate over it to secure the adjustment setting.
Replace the faucet knob and secure with the screw or set screw, depending on your model.