Boiler displays HLP or High Pressure; relief valve may drip or discharge water.

Safety first: High pressure can cause the relief valve to discharge hot water. Keep clear of the relief outlet. Allow the system to cool before working on it.

• Check pressure gauge: Confirm the actual system pressure. If it is above 30 psi, the relief valve may open. Do not ignore repeated discharge.
• Inspect expansion tank: Locate the expansion tank near the Laars boiler. If it feels completely full of water and heavy, it may be waterlogged. Tapping it should produce a hollow sound on the air side; a solid sound indicates waterlogged.
• Check fill valve: Ensure the manual shutoff to the automatic fill valve is not stuck open or misadjusted. If the system pressure rises even when cold, the fill valve may be feeding too much water.
• Reduce pressure (temporary): A trained person can carefully drain a small amount of water from a drain valve to bring pressure down to a safe level. Collect water in a bucket and avoid contact with hot water.

When to call a professional: Expansion tank replacement, fill valve adjustment, and diagnosis of overheating should be done by a qualified technician.