Patent ID: 7059536

Claim:
An air circulation system having ductwork for use in managing a controlled space, said air circulation system comprising: an outside air duct for presenting an outside air stream to said controlled space; a return air duct for presenting a return air stream to said controlled space, said return air stream comprising air previously circulated through said controlled space and mixing with said outside air stream prior to said outside air stream and said return air stream being presented to said controlled space; a controller; a return damper apparatus operatively connecting said return air duct to said ductwork; a heating unit; an air mass sensor for selectively and directly detecting only a ventilation rate of said return air stream moving through said return damper apparatus and communicating said ventilation rate to said controller; a discharge temperature sensor for detecting a temperature of air discharged from said heating unit; and wherein said controller selectively modulates operation of said heating unit in dependence upon said ventilation rate and said discharged air temperature.