Lochinvar water heater shows E018; may be associated with low water pressure or air in system.

Safety: Hot water and steam can cause burns. Allow system to cool and relieve pressure before opening any vents or drains.

Steps:

• 1. Check system pressure: On hydronic or indirect systems, verify the pressure gauge reads within Lochinvar's recommended range (often 12–25 psi). If low, add water through the fill valve or have the automatic fill valve serviced.
• 2. Bleed air: Open air vents on high points or radiators to remove trapped air that can cause false low-flow or low-level readings.
• 3. Inspect for leaks: Look for water around pumps, valves, and the tank. Repair any leaks before refilling.
• 4. Test pressure sensor/switch: Check wiring and, if accessible, test the low water cutoff or pressure switch per Lochinvar procedures. Replace if defective.
• 5. Reset and monitor: After restoring proper pressure and bleeding air, reset the unit and monitor for recurring E018.