Boiler shows E16, no heating or hot water, may occur after wiring changes

Safety: Isolate power before working on control wiring.

• Check programmer and thermostat: Ensure the programmer is set to ON and the room thermostat is turned up above room temperature.
• Inspect wiring at boiler: Remove the front panel to access the terminal strip and verify that the call-for-heat terminals are correctly wired or bridged as per the Main installation manual.
• Bypass external controls (test only): Fit a temporary link across the room thermostat terminals at the boiler. If the boiler runs, the fault is in the external controls or wiring.
• Engineer tasks:
  • Trace and repair any breaks in the thermostat cable.
  • Replace faulty room thermostat or programmer.
  • Confirm correct configuration of the boiler PCB for the type of control used (on/off vs. modulating).