You can fix this
Likely cause: the limit stop is set too high
If full hot scalds, the limit stop lets the handle turn too far. Turn it down to 120F or less.
Why this happens
The limit stop under the handle sets the hottest water the valve will deliver. Moen, Kohler and CPSC all point to 120F as the safe ceiling. CPSC says 150F water can cause a third-degree burn in two seconds, 140F in six seconds, and 130F in thirty seconds, so a stop set too high is a real burn risk.
How to fix it
- Shut off the water to the shower before you remove the handle.
- Find the limit stop under the handle. Moen Posi-Temp stops pull out and reseat in a different notch; Kohler Rite-Temp valves use a red and black collar on the brass stem.
- Move it one step toward cooler, following your valve's guide linked below. Do not guess the direction; brands differ.
- Turn the water back on, run full hot, and check with a thermometer.
- Repeat until the hottest flow reads 120F or less.
When to stop. If you cannot get the hottest water down to 120F at the valve, lower the water heater setting and call a plumber.
If this does not fix it, tell the plumber
- The shower runs too hot at full hot, and the reading you got with a thermometer.
- The valve brand and model.
- Whether young children or older adults use the shower.
Build the full list: what to tell the plumber.
Start this troubleshooter over
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