Came out today for a no heat call on a crown boiler system. Upon inspection I found that the system has 2 zones. I tested each zone separately and I found that the zone valve for the main house was not receiving 24 volts to open. I went to the thermostat and found that the batteries needed to be replaced. I replaced the batteries and called for heat again. The zone valve was now receiving 24 volts and was open. I let the system run for about 10 minutes and the baseboard heater was indeed getting hot. I turned the system off and tested again to insure that there were no other issues with the system. The system is operating properly at this time.