Safety relief valve test

What is going on

This is the annual test of the boiler safety relief valve. The valve is the last line of defense against overpressure, so it needs to move freely and seal again afterward. Before lifting the lever, understand that discharge can be near boiler temperature and can scald, so confirm the discharge piping is routed to a safe spot and nobody is standing near the outlet. Let the boiler cool to a safe temperature first, and do not test it if the discharge pipe is missing.

Likely causes

• Valve seat holding debris, causing leakage
• Mineral deposits or scale on the seat after years without testing
• Valve stuck from never being operated
• Discharge piping missing or not supported

Check in this order

1. Confirm the valve discharge piping is installed correctly and supported, and that it points somewhere safe from scalding water.
2. Check the boiler operating pressure.
3. Lift the test lever to the full open position and hold for at least five seconds, or until clean water discharges.
4. Release the lever and let the valve close. If it leaks, operate the lever two or three times to clear the seat. Allow time to confirm the valve has fully closed.
5. If the valve keeps leaking, replace it before returning the boiler to service. Never plug or cap a relief valve.
6. Confirm operating pressure has returned to normal, and top up if the fill valve did not.
7. Check again that the valve has closed fully and is not leaking.

More boiler guides

• 0-10 VDC input to modulate firing rate (Mode 5)
• Annual maintenance and inspection
• Blank display
• Boiler pressure keeps dropping / FILL shows
• Boiler shows FILL and will not fire
• Cleaning the combustion side of the heat exchanger