The zone valve to one of my buildings is constantly opening and closing. Within minutes. I checked the sensor on another building and it is working fine. I don't know if the valve is not getting a signal, maybe a wire is loose (although I have followed them and don't see evidence of this). Is my thermostat box messed up. The only way I could get the zone valve to stop was to cut the power wires. I can now hook them up - let it either open or close depending on whether building is too hot or too cold - then unhook the wires to leave valve in either open or closed position. What do I need to do? New zone valve? Maybe a new thermostat. I think the sensor is working fine.

First thing to check is if the wire has been pinched of smashed anywhere.

Thanks for the input. I have gone through and tested the sensor, and the thermostat. They are both good. Both work fine when connected to a different zone valve. I have checked all the wires and they seem intact and going to the correct places. I have decided it may just be the zone valve. I am ordering another one right after I answer this post. Thank you for your insight though.