The answer to 'why is my zone control system not turning on' is that there could be several common causes, such as a thermostat or sensor issue, a problem with the control panel or wiring, or a power supply problem. Some common symptoms include the system not responding to temperature changes, inconsistent heating/cooling in different zones, or the control panel not powering on.
To troubleshoot, you'll want to check the thermostat and sensors to ensure they are functioning properly, inspect the control panel and wiring for any damage or loose connections, and verify that the system is receiving power. If you're not comfortable doing this yourself, it's best to call in a professional HVAC technician who can properly diagnose and repair the issue.