Preset timed control for HVAC operation

Claim 1

A control system for an existing central heating, ventilating and cooling until (HVAC), said system comprising a selector controller and a conventional plug in timer, the controller adapted to be connected in electrical series between an existing HVAC thermostat and an existing low voltage control circuit for actuating conventional devices in the HVAC, said controller comprising a relay, a relay operated switch connected in circuit with a three position manual switch, said manual switch having a first off position, a second timed position in which the manual switch is series connected with said relay switch and a third normal position by-passing said relay switch, said plug in timer having a timer operated switch and said timer being connected to said relay by an external cord plugged into the timer, said timer adapted for plugging into a standard wall outlet, said system operating such that when the manual switch is in the timed position the thermostat operates the HVAC only when the timer operated relay switch is closed and when in the normal position the thermostat controls the HVAC.