F.14
Glow-worm Zone Configuration / Addressing Error

Thermostat shows F.14 and cannot control heating zones correctly

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Duplicate zone address on multiple Glow‑worm zone modules, Incorrect zone assignment in installer menu, Faulty zone control module, Mis‑wired zone valve outputs

How to Fix / Troubleshooting

Safety: Isolate mains power to the wiring center and boiler before working on zone modules or valve wiring.

Diagnosis:

  • Identify all Glow‑worm zone control modules and note their configured addresses or DIP switch settings.
  • Ensure each zone module has a unique address and that it matches the zone configuration in the thermostat installer menu.
  • Check wiring from each zone module to its corresponding zone valve or pump. Look for crossed connections or shared neutrals that could cause feedback.
  • Temporarily disconnect all but one zone module and test if F.14 clears when only a single zone is active.

Remedy:

  • Correct any duplicate addresses and reconfigure zones in the thermostat.
  • Replace any zone module that does not respond correctly when addressed individually.
  • After re‑wiring and configuration, restore power and test each zone independently from the thermostat.
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Repair Difficulty

Hard 4/5

Required Part

Glow-worm multi‑zone control module
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