Patent ID: 7475558

Claim:
A cooling system for a multi-level space having at least one lower level return air duct and at least one upper level return air duct, the system comprising: a thermostat having a sensor for sensing the temperature in the lower level, the thermostat being capable of controlling the operation of the cooling system by switching a low voltage activation signal transmitted by the thermostat via a wire connected to the cooling system; a remote sensor in the upper level for communicating upper level temperature information to the thermostat; and a motorized damper installed in each of the at least one lower level return air ducts, each motorized damper having connection means for connecting the motorized damper in parallel with the wire transmitting the low voltage activation signal to the cooling system, such that each motorized damper is actuated and moves to an open position when the thermostat switches a low voltage activation signal to the cooling system, wherein each motorized damper is deactuated when the thermostat switches a low voltage activation signal to the circulating fan only, and is operatively closed by a return spring; wherein the thermostat sends a low voltage signal to the circulator fan for activating the circulator fan when the sensed upper level temperature is more than a predetermined amount above the sensed lower level temperature, such that with the dampers in the lower level return air duct being closed by a return spring, the circulating fan substantially draws no return air flow through each lower level return air duct and effectively draws return air flow only from the at least one return air duct in the upper level of the space, to redistribute warm air from the upper level and reduce the temperature stratification in the space.