E07 error and the boiler fails to fire when the store is cold.

Safety: All work on mains‑voltage boiler control circuits must be carried out with the power isolated. If unsure, use a qualified electrician or heating engineer.

Steps:

• Check boiler operation independently: If the boiler has its own controls, confirm it can fire when called directly. If not, the issue may be with the boiler, not the Gledhill unit.
• Inspect wiring: Trace the boiler enable/call‑for‑heat cable from the Gledhill PCB to the boiler terminals (often marked TA, RT, or room stat). Look for loose connections or any damaged cable.
• Relay test: With power on and a heat demand present, listen for a click from the PCB relay. If no click and E07 is displayed, the relay or the PCB is likely faulty.
• Voltage check: Measure across the boiler enable terminals when there is a demand. If the expected switched live/volt‑free contact is not present, the PCB output is defective.

Remedy: Repair or replace any damaged wiring. If the PCB relay is faulty, the main control PCB will usually need replacement. Label all connections carefully before swapping boards.