A plumber is called to a healthcare facility to address a leaking thermostatic mixing valve (TMV) that supplies tempered water to a patient bathing area. After isolating the water supply, which of the following is the most likely cause of a continuous drip from the valve body?

Question: A plumber is called to a healthcare facility to address a leaking thermostatic mixing valve (TMV) that supplies tempered water to a patient bathing area. After isolating the water supply, which of the following is the most likely cause of a continuous drip from the valve body?

Answer options:

• Improper calibration of the thermostat. ✅ Worn O-rings or seals within the valve cartridge.
• Insufficient hot water temperature supply.
• Excessive water pressure to the mixing valve.

Correct answer: Worn O-rings or seals within the valve cartridge.

Explanation: A continuous drip from the valve body typically indicates a physical breach in the sealing components. Worn O-rings or seals within the cartridge are common culprits for leaks. Calibration issues or water temperature/pressure problems would usually affect the mixed water temperature or flow, not cause an external leak from the valve body itself.