Kospel Overheating / Thermostat Control Issue

Furnace runs continuously and overshoots the room temperature set on the thermostat.

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.

Possible Causes

Faulty room thermostat, Thermostat located in wrong place, Stuck relay on control board, Incorrect wiring bypassing thermostat

Safety: Turn off power before altering control wiring.

Check thermostat location: Ensure it is not near heat sources or in direct sunlight.
Test thermostat: Lower the setpoint below room temperature; the furnace should stop. If not, the thermostat or wiring may be faulty.
Inspect wiring: Confirm that the thermostat is correctly wired to the Kospel control terminals and not permanently bridged.

If the furnace continues to run with thermostat disconnected, the control board relay may be stuck and needs replacement.

Medium 3/5

Room Thermostat / Main Control PCB

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