Boiler pressure gauge frequently rises above 30 psi and relief valve discharges water

Safety first: Allow the system to cool before relieving pressure. Hot water discharge can cause burns.

• Step 1 – Check system pressure cold: When the system is cold, note the pressure. It should typically be around 12–20 psi. If higher, carefully drain some water from a drain valve to reduce pressure.
• Step 2 – Inspect expansion tank: Tap the tank; if it sounds solid and heavy, it may be waterlogged. With system pressure at zero, check the air charge at the Schrader valve (should match design pressure). Recharge or replace the tank if no air charge is present.
• Step 3 – Check fill valve: If pressure continues to rise on its own, the automatic fill valve may be leaking by and should be repaired or replaced.
• Step 4 – Verify expansion tank connection: Ensure the piping between the system and expansion tank is not blocked or valved off.

Do not cap or plug the pressure relief valve; it is a critical safety device.