Abstract: A temperature control system for a building structure such as a household is divided into a plurality of zones. A controller acts between temperature sensing devices in each of the zones and an adjustable thermostat which allows the desired temperature in the building structure to be selected. The controller allows individual zones to be selected to receive conditioned air and allows one of the selected zones to be designated as a control zone. A heating or cooling decision for the temperature control system for all of the selected zones is made based on the difference between the thermostat setting and the output of the temperature sensing device in the control zone. The control zone can be changed manually to the next available selected zone. Different visual indications are given for the control zone and the selected zones. Zones with faulty temperature sensing devices cannot be control zones or selected zones.