In reply to by Tom

October 05, 2022

Tom, You should have a "green" power light lit at all times.  The "red" zone lights will illuminate whenever a specific zone thermostat call for heat.    If you don't have the green power light the board may be shut down by the internal resettable breaker.   I would disconnect the thermostat wires to all zones and any other low voltage wiring and power the board back on.  If the power light comes on you have a short in the low voltage wiring.  You can also, using your voltmeter look for 24v between the R & C terminals at any of the thermostat locations.   I would recommend calling Caleffi Tech Support for other troubleshooting tips 414-238-2360. 

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