The answer to 'why is my zone control system short cycling' is that it is likely due to a problem with the thermostat, wiring, or the zone control board. Short cycling occurs when the system turns on and off rapidly, before it can complete a full heating or cooling cycle. This can be caused by issues like a malfunctioning thermostat, improper thermostat placement, a problem with the wiring, or a faulty zone control board.
If the thermostat is not calibrated correctly or is located in a spot that doesn't accurately represent the temperature in the zone, it can cause the system to short cycle. Wiring issues like loose connections or damaged wires can also lead to short cycling. Additionally, a problem with the zone control board itself, such as a faulty relay or control chip, can prevent the system from running properly.