IBC
No Call for Heat Recognition
Boiler display is on but there is no response to thermostat calls; unit stays in standby.
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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
Open thermostat circuit, Miswired control terminals, Faulty external controller, Incorrect control mode settings
How to Fix / Troubleshooting
Safety: Turn off power before changing low-voltage wiring.
- Check thermostat wiring: Verify the thermostat or zone controller wires are connected to the correct TT or demand terminals on the IBC boiler.
- Bypass test: Temporarily jumper the call-for-heat terminals at the boiler. If it starts, the issue is upstream (thermostat or wiring).
- Control mode: Confirm the boiler is configured for the type of control you are using (e.g., on/off thermostat vs. 0–10V signal).
If the boiler still does not respond to a direct jumper, the control board input may be faulty and requires professional diagnosis.
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Repair Difficulty
Medium
3/5
Required Part
Low-Voltage Control Terminal Block
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