Sub-zone kit designed for independent temperature control in air conditioning equipment using ducts, with which it acts only in certain zones of the installation, leaving others free. Particularly suitable for medium- and large-scale installations for avoiding occasional excessive heating or cooling in certain zones (meeting rooms, offices, etc.). Control over up to 6 independent zones. The system is independent of the air-conditioning equipment. Automatic summer/winter changeover by means of a duct-mounted NTC sensor. Radio-controlled digital thermostats with timing in 30 minute intervals.