Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: A heating or cooling system, such as an HVAC system, of variable output has a number of control elements and may include a variable speed compressor, a variable speed combustion (induced or forced draft) blower motor; a variable speed circulator blower motor; a variable output gas valve or gas/air premix unit; and a controller specifically developed for variable output applications. The system may utilize a pressure sensor to determine the actual flow of combustion airflow in response to actual space conditions, vary the speed of the inducer blower, and subsequently vary the gas valve output to supply the correct amount of gas to the burner system. A temperature sensor may be located in the discharge air stream of the conditioned air to provide an input signal for the circulator blower.

Abstract: Furnace control for a forced air furnace utilized in multi-zone heating. The forced air furnace is made up of return ducts, a heat exchanger, warm air ducts, a circulation blower, and a burner. The forced air furnace receives heating requests from external control means wherein the furnace provides heat to a zone or multiple zones to be heated. The control for the furnace comprises a temperature sensor for sensing the temperature of the heat exchanger, a regulator for regulating the burner to hold the temperature at the heat exchanger constant during the on cycle of the furnace, a pressure sensor for measuring the pressure in the heat exchanger and a controller for controlling the circulation blower in order to maintain a constant pressure within the heat exchanger.

Abstract: An adaptive furnace controller utilizing analog temperature sensing to maintain a constant preselected temperature in the heat exchanger during operation. The adaptive furnace control measuring heat exchanger temperature and regulating a controllable valve to adjust burner firing rate, thereby holding heat exchanger operating temperature constant. Further, creating constant on/off times based on the previous cycle on/off times of the furnace by regulating circulation blower speed. By increasing blower speeds to shorten "on" times or decreasing blower speeds to increase "on" times, and thereby achieving optimum cycle times.

Abstract: A gas burning furnace has a burner in which the premixed fuel/air ratio of the burned gas in the burner flame is measured by a flame rod sensing the ionization current. The flame rod is connected to a fuel/air controller which controls the gas and primary air to the burner to maintain the maximum flame ionization current which results in an excessive amount of gas to the burner. The secondary air to the combustion chamber is proportionally controlled to add sufficient oxidant to the gas combustion in the combustion chamber to ensure complete combustion. Other properties of the flame or combustion products can also be used.

Abstract: Disclosed is a fuel gas control for controlling the delivery of fuel gas. The present gas control comprises an inlet chamber having an inlet for receiving a supply of gas and an outlet chamber having an outlet for providing a supply of gas. The inlet and outlet chambers are connected by a valve opening. A valve is operatively associated with the opening. The valve has a closed position for preventing the flow of gas through the opening and an open position for permitting the flow of gas through the opening. The present control further comprises control chamber means for moving the valve between its open and closed positions in response to pressure variations within the control chamber means. The present control further comprises apparatus for directly connecting the control chamber means to a pressure signal from a power combustion air blower so that the valve is positioned in response to the pressure signal from the combustion air blower.

Abstract: A furnace stack damper control apparatus has a motor for connection to a stack damper to open the damper upon a call for heat by a space thermostat. The motor is driven in a closed direction by electrical energization and in an open direction by a spring return. A relay having two normally open switches and a normally closed switch is energized when a space thermostat calls for heat. The normally closed switch then opens to allow the damper motor to open the damper by the spring return. The motor has an end switch having a normally open and a normally closed circuit. The normally open circuit is used with one of the normally open switches of the relay to energize a gas valve when the damper is open. The normally closed end switch is used to provide the energization circuit for the relay by the space thermostat and the relay is maintained energized when the damper is open by the other normally open switch of the relay connected in parallel to the normally closed end switch.

Abstract: Apparatus is provided for modifying an open draft hood furnace and its control system, to produce an induced draft furnace having increased efficiency. A blower located in the furnace exhaust stack is used to induce movement of air and combustion products into and through the draft hood. A flow-limiting orifice located in the exhaust stack upstream from the blower causes a region of reduced pressure to exist downstream from the orifice. A pressure signal representative of the flow rate of exhaust stack gases is sensed on the downstream side of the orifice and is communicated by a conduit to a pressure switch connected to a gas valve, which together control gas to the burner. No gas is permitted to flow to the burner unless a predetermined reduced pressure level is achieved at the downstream side of the orifice. A small opening in the conduit permits a small flow of flushing air to enter the conduit.

Abstract: An induced draft combustion apparatus and its associated control system has a blower located in the exhaust stack or vent which is used to induce the movement of air and combustion products into, through and out of the combustion chamber. A flow-restricting orifice in the exhaust stack near the blower causes a region of higher pressure to exist upstream from the orifice with a region of lower pressure downstream from the orifice. An exhaust gas pressure signal representative of the exhaust gas volume flow rate is sensed on one side of the orifice and is fed back to a modulating gas valve which controls the outlet gas flow from the valve to be proportional to the magnitude of the exhaust gas volume flow rate. By controlling blower speeds and exhaust gas volume flow capacities as related to a selected orifice size, various firing rates for the furnace can be selected, from the design maximum down to various derated levels.

Abstract: Apparatus is provided for constructing an induced draft furnace and its control system, to produce an induced draft furnace having increased efficiency. A blower located in the furnace exhaust stack is used to induce movement of air, fuel and combustion products into, through and out of the combustion chamber. A flow-limiting orifice in the exhaust stack in proximity to the blower causes a region of higher pressure to exist upstream from the orifice, with a region of lower pressure downstream from the orifice. A pressure signal representative of the flow rate of exhaust stack gases is sensed on one side of the orifice and is fed back to a modulating gas valve which controls the outlet gas flow from the valve to be proportional to the magnitude of the pressure signal representing exhaust stack flow rate. By selecting blower speeds and flow capacities, various firing rates for the furnace can be selected, from the design maximum of the furnace down to various derated levels.