A.O. Smith Over-Pressure or Over-Temperature Relief Discharge

Water leaking from temperature and pressure (T&P) relief valve on A.O. Smith water heater

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Excessive system water pressure, No thermal expansion tank on closed system, Faulty T&P valve, Thermostat overheating water

How to Fix / Troubleshooting

Safety: The T&P valve is a critical safety device. Do not cap or plug it.

  • 1. Check water temperature: Run hot water at a faucet and measure temperature. If above 140°F without reason, the thermostat or gas control may be faulty.
  • 2. Test T&P valve: Lift the test lever briefly to flush debris. If it continues to drip afterward, the valve may be worn and should be replaced.
  • 3. Measure pressure: Use a pressure gauge on a nearby faucet to check static water pressure. If above 80 psi, install or service a pressure-reducing valve.
  • 4. Install expansion tank: On closed systems (with check valves or PRVs), install a properly sized thermal expansion tank on the cold inlet to absorb expansion.
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Repair Difficulty

Medium 3/5

Required Part

Temperature and Pressure Relief Valve
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