Patent ID: 8777119

Claim:
A heated air makeup unit for heating outside air and directing the outside air into an interior space, the heated air makeup unit comprising: a. a housing; b. a heating chamber disposed in the housing; c. a furnace unit disposed in the housing and including a modulated gas furnace and one or more non-modulated gas furnaces; d. wherein each of the one or more non-modulated furnaces is operative to function at a substantially constant heating rate and wherein the modulated furnace is operative to function at a varying heating rate; e. a combustion air blower and a modulated gas valve associated with the modulated gas furnace, and wherein by controlling the combustion air blower and the modulated gas valve associated with the modulated gas furnace, the heating rate of the modulated furnace can be varied and controlled; f. a combustion air blower associated with each non-modulated gas furnace for supplying combustion air to each non-modulated gas furnace; g. an air inlet for directing air into the heating chamber; h. an air outlet for directing heated air from the heating chamber; i. wherein air is directed into the air inlet and past the one or more non-modulated furnaces and the modulated furnace where the air is heated; j. a control system for controlling the furnace unit, the control system operative to provide control of the furnace unit by selectively activating or deactivating one or more of the non-modulated furnaces, and operative to provide control of the furnace unit by varying the heating rate of the modulated furnace, the control system including: 1) a speed control unit operatively connected to the combustion air blower associated with the modulated gas furnace for varying the speed of the combustion air blower and varying the flow of combustion air into the modulated gas furnace; and 2) a controller having a command signal input for receiving a command signal and for: a) actuating and de-actuating the one or more non-modulated gas furnaces; b) controlling the modulated gas valve associated with the modulated gas furnace and varying the flow of gas to the modulated gas furnace; c) controlling the speed control unit which, in turn, is operative to control and vary the speed of the combustion air blower associated with the modulated gas furnace; and d) wherein the controller is operative to provide control of the furnace unit by providing on/off control of the one or more non-modulated gas furnaces and the combustion air blowers thereof, and to provide control of the furnace unit by controlling the gas modulated valve and combustion air blower associated with the modulated gas furnace.