The answer to 'why is my zone control system not heating' is that there are several common causes, including issues with the thermostat, wiring problems, or a malfunction in the zone control panel. Symptoms may include some zones not heating, uneven temperatures, or the system not responding to temperature changes.
Some potential solutions include checking the thermostat settings, inspecting the wiring for any loose connections or damage, and testing the zone control panel to see if it needs repair or replacement. If the issue persists, it's best to call a professional HVAC technician to diagnose and fix the problem, as zone control systems can be complex and require specialized expertise.