A13
Herz
External Safety Chain Open (e.g., limit stats, external interlocks)
Boiler shows A13, external safety circuit open, no operation
Advertisements
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.
Advertisements
Possible Causes
Open external safety thermostat, tripped low-water cut-off, open flue gas safety thermostat, wiring break in safety loop
How to Fix / Troubleshooting
Safety: Identify why a safety device has opened before resetting. Do not bypass safety devices.
- Check external stats: Locate any external high-limit thermostats or flue stats connected to the Herz boiler. Reset only if the cause (overheat, blocked flue) has been corrected.
- Inspect low-water cut-off: Ensure system pressure and water level are adequate. Reset the device if fitted and safe to do so.
- Check wiring: Trace the safety loop wiring from the boiler terminals to each device, looking for loose or broken connections.
- Persistent A13: Have a technician test each safety device and replace any faulty Herz-branded safety thermostat or sensor.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Herz safety thermostat (external circuit)
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements