Gledhill thermal store boiler runs continuously and store overheats

Safety: Overheating can damage the cylinder and boiler. If the store is excessively hot or venting, isolate power and boiler immediately.

Steps:

• Check thermostat: Turn the cylinder thermostat down to minimum. If the boiler continues to run, the thermostat or PCB is likely stuck on.
• Relay test: With power off, inspect the PCB boiler relay for signs of welding or burning. Replace the PCB if the relay is defective.
• External controls: Verify that any external programmers or room stats are wired correctly and not permanently calling for heat.
• Valve position: Ensure motorised valves are not jammed in an open position that constantly feeds the cylinder.

Note: Do not leave the system running unattended if it is unable to regulate temperature correctly.