Apparatus and method for controlling a variable air volume temperature conditioning system

DETAILED DESCRIPTION We claim: 1.
A method for controlling a temperature conditioning system having a plurality of stages which may be selectively energized to meet a temperature conditioning demand in a comfort zone, comprising the steps of controlling the temperature in the comfort zone approximately at a setpoint by adjusting the flow of temperature conditioned air supplied to the comfort zone; sensing the temperature of return air; sensing the temperature of temperature conditioned supply air; controlling selected apparatus of the temperature conditioning system in response to the differential temperature of the return air and the temperature conditioned supply air, to meet the temperature conditioning demand in the comfort zone.
2.
A method for controlling the operation of components of a cooling system in which a plurality of cooling stages may be selectively energized to meet a cooling demand in a comfort zone into which the flow of cooled air is varied in response to temperature therein, said method comprising the steps of sensing the temperature of cooled supply air; sensing the temperature of return air; controlling the operation of the cooling system components in response to the differential temperature of the return air and the cooled supply air, whereby successive stages of cooling are energized as a function of the differential temperature of the return air and the cooled supply air.
3.
The method of claim 2 further comprising the step of de-energizing the stages of cooling as a function of the differential temperature of the return air and the cooled supply air.
4.
The method of claim 3 further comprising the steps of energizing a first stage of cooling if the differential temperature is less than a first minimum predetermined limit; and thereafter, following a time delay after each change of staging, successively energizing one or more additional stages of cooling if the differential temperature is less than other minimum predetermined limits for each said one or more additional stages of cooling, respectively; and de-energizing the stages of cooling if the differential temperature exceeds other maximum predetermined limits which are substantially different than the respective minimum predetermined limits for each stage of cooling, whereby the maximum and minimum predetermined limits for each stage provide hysteresis for the addition and the deletion of cooling stages