Lochinvar
Excessive Temperature or Pressure / T&P Valve Operation
Lochinvar water heater T&P relief valve is dripping or discharging water periodically.
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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
Thermal expansion with no expansion tank, High incoming water pressure, Faulty T&P relief valve, Overheating due to thermostat failure
How to Fix / Troubleshooting
Safety: The T&P valve is a critical safety device. Do not cap or plug it. Water may be extremely hot.
Steps:
- 1. Check system pressure: Use a pressure gauge on a nearby faucet to measure static and dynamic pressure. If above 80 psi, install or service a pressure-reducing valve.
- 2. Install expansion tank: If a check valve or backflow preventer is present on the cold supply, install a properly sized thermal expansion tank on the cold inlet.
- 3. Test T&P valve: Lift the test lever briefly to flush debris, then release. If it continues to drip, replace the T&P valve with a Lochinvar-approved rating.
- 4. Check for overheating: Verify thermostat operation and outlet temperature. If water is excessively hot, address thermostat or control issues.
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Repair Difficulty
Medium
3/5
Required Part
Temperature & Pressure Relief Valve
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