Hi @South Africa C4 user I have 4 HVAC systems (not zones), 3 systems are already connected via zigbee thermostats to the EA controller, one per system. Planning on adding another zigbee thermostat for the 4th system. All thermostats are the same (https://c4smartsolution.com/control4-wireless-thermostat-by-aprilaire-8644c4/), hence assuming no new driver needed.