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.
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.