Alarm! Why Is My Tankless Water Heater Hissing and Leaking from the Relief Valve?

A leaking relief valve on a tankless water heater can be a perplexing and disconcerting issue. Understanding the underlying causes can empower you to address the problem effectively and restore your water heater to its optimal functionality.

Causes of a Leaking Relief Valve

1. Excessive Water Pressure: The relief valve is designed to release excess water pressure within the water heater. If the incoming water pressure exceeds the recommended limit, the valve will open to prevent the tank from rupturing.

2. Faulty Pressure Reducing Valve: The pressure reducing valve (PRV) is responsible for regulating the incoming water pressure. A malfunctioning PRV can lead to excessive pressure, triggering the relief valve to leak.

3. Thermal Expansion: When water is heated, it expands. If the expansion tank is not properly sized or malfunctioning, the excess pressure created by thermal expansion can cause the relief valve to leak.

4. Debris or Sediment Accumulation: Sediment or debris can accumulate in the relief valve, preventing it from closing properly and causing a leak.

5. Corrosion or Wear: Over time, the relief valve can become corroded or worn, impairing its ability to seal effectively.

6. Improper Installation: If the relief valve is not properly installed or secured, it can leak due to a loose connection or improper sealing.

7. Manufacturing Defect: In rare cases, the relief valve itself may have a manufacturing defect that causes it to leak.

Troubleshooting and Repair Steps

1. Check Water Pressure: Use a water pressure gauge to verify if the incoming water pressure is within the recommended range. If it’s too high, a PRV adjustment or replacement may be necessary.

2. Inspect the PRV: Ensure the PRV is functioning correctly by checking for signs of leaks or damage. If faulty, replace the PRV.

3. Check the Expansion Tank: Verify the expansion tank is properly sized and operational. If it’s too small or malfunctioning, replace it.

4. Clean the Relief Valve: Remove the relief valve and clean it thoroughly to remove any debris or sediment. Ensure the valve seat is free of obstructions.

5. Replace the Relief Valve: If cleaning the valve doesn’t resolve the leak, it may need to be replaced. Use a new relief valve with the same pressure rating as the original.

6. Contact a Professional: If you’re unable to identify or resolve the cause of the leak, it’s advisable to contact a qualified plumber for assistance.

Preventive Maintenance Tips

1. Regular Water Pressure Checks: Monitor your water pressure periodically and adjust the PRV as needed to prevent excessive pressure.

2. Annual Tankless Water Heater Inspection: Schedule an annual inspection with a qualified technician to ensure the relief valve is functioning properly and the system is operating efficiently.

3. Sediment Filter Installation: Install a sediment filter at the water inlet to prevent debris from entering the water heater and clogging the relief valve.

4. Proper Sizing of Expansion Tank: Ensure the expansion tank is properly sized for your water heater capacity. A too-small tank can lead to excessive pressure and relief valve leaks.

In a nutshell

Understanding the causes of a leaking relief valve on a tankless water heater is crucial for timely and effective troubleshooting. By following the steps outlined above, you can diagnose the issue, implement appropriate repairs, and implement preventive measures to ensure the optimal performance of your water heater. Remember, if the problem persists or you encounter any complexities, don’t hesitate to seek professional assistance.

Frequently Asked Questions

Q1: Is it safe to use a tankless water heater with a leaking relief valve?
A1: No, it’s not safe to operate a tankless water heater with a leaking relief valve. The leak indicates a potential overpressure issue that could lead to a rupture or explosion.

Q2: Can I replace the relief valve myself?
A2: While it’s possible to replace the relief valve yourself, it’s generally recommended to have a qualified plumber perform the task to ensure proper installation and safety.

Q3: How often should I replace the relief valve on my tankless water heater?
A3: The frequency of relief valve replacement depends on the water quality and usage patterns. It’s generally recommended to replace the valve every 5-10 years or as recommended by the manufacturer.