Abstract: A forced air furnace may include a pneumatically modulated gas valve that is configured to provide gas to a burner. A pneumatic sampling device may be disposed proximate a combustion blower and may be configured to provide the pneumatically modulated gas valve with a first pneumatic signal and a second pneumatic signal that are representative of fluid flow through the pneumatic sampling device. The pneumatically modulated gas valve may regulate gas flow in accordance with the first and second pneumatic signals. In some cases, the pneumatic sampling device may include a restriction, a first pressure port disposed upstream of the restriction and a second pressure port disposed downstream of the restriction. The first and second pressure ports may provide the first and second pneumatic signals to the pneumatically modulated gas valve.

Abstract: Systems and methods for controlling gas to gas-fired appliances are disclosed. An illustrative system can include a modulating gas valve adapted to supply gas to a burner unit, an inducer fan adapted to produce a combustion air flow at the burner unit, a pressure reducing element in fluid communication with the gas valve and adapted to output at least one pressure signal for sensing the combustion air flow outputted by the inducer fan, and a controller for controlling the speed of the inducer fan. The pressure reducing element can include a venturi tube, flow nozzle, or other suitable device capable of producing pneumatic signals that can be used by the gas valve to modulate the gas supplied to the burner unit. By pneumatically linking the gas valve to the actual combustion air flow, the gas valve can be operated over a wide range of firing rates by adjusting the speed of the inducer fan.

Abstract: Systems, methods, and controllers for controlling gas-fired appliances such as warm air furnaces are disclosed. An illustrative furnace system can include a burner unit in communication with a combustion air flow conduit and heat exchanger, a variable speed inducer fan or blower adapted to provide a flow of combustion air to the burner unit, a furnace controller and motor speed control unit adapted to regulate the speed of the inducer fan or blower, and a pneumatically modulated gas valve adapted to variably output gas pressure to the burner unit based at least in part on the combustion air flow.

Abstract: A fault detection system and method for a warm air furnace is provided. A sensing circuit connected to an AC power source measures a level of current consumption during several points in the warm air furnace operating sequence. The measured level of current consumption is compared with an expected value. If the measured level exceeds the expected level by a threshold amount, a fault in the warm air furnace may be detected. An indication of at least one warm air furnace component that is most likely to have caused the fault may be provided.

Abstract: A burner assembly for use in a warm air furnace. The burner assembly has a cooling air box for receiving air and a premix burner for receiving air-fuel premix positioned within and spaced apart from the cooling air box. The burner assembly also has a burner face assembly defining a front end of the premix burner. The burner face assembly includes a first plate positioned on top of a second plate, and a third plate positioned underneath the second plate. Each plate of the burner face assembly has a plurality of aligned burner openings. In the burner assembly, air-fuel premix is pulled through the premix burner, air is pulled through the cooling air box to cool the premix burner, and flames are projected from each of the burner openings of the burner face assembly for transferring heat within the warm air furnace.

Abstract: A warm air furnace system has a valve for controlling the flow of fuel, and a mixing component for receiving fuel from the valve and mixing the fuel with air to form an air-fuel premix. The warm air furnace system also has a burner assembly for receiving the air-fuel premix from the mixer, and an inducer for pulling the air-fuel premix through the burner assembly. The air-fuel premix drawn from the burner assembly is ignited into a flame by an ignition element. The flame transfers heat to a heat exchanger in communication with and positioned between the burner assembly and the inducer. The heat exchanger, in turn, transfers heat to air being passed over the heat exchanger by a circulation fan. The heated air passed over the heat exchanger then provides heat to a user of the furnace.

Abstract: A warm air furnace system has a valve for controlling the flow of fuel, and a mixing component for receiving fuel from the valve and mixing the fuel with air to form an air-fuel premix. The warm air furnace system also has a burner assembly for receiving the air-fuel premix from the mixer, and an inducer for pulling the air-fuel premix through the burner assembly. The air-fuel premix drawn from the burner assembly is ignited into a flame by an ignition element. The flame transfers heat to a heat exchanger in communication with and positioned between the burner assembly and the inducer. The heat exchanger, in turn, transfers heat to air being passed over the heat exchanger by a circulation fan. The heated air passed over the heat exchanger then provides heat to a user of the furnace.

Abstract: A burner assembly for use in a warm air furnace. The burner assembly has a cooling air box for receiving air and a premix burner for receiving air-fuel premix positioned within and spaced apart from the cooling air box. The burner assembly also has a burner face assembly defining a front end of the premix burner. The burner face assembly includes a first plate positioned on top of a second plate, and a third plate positioned underneath the second plate. Each plate of the burner face assembly has a plurality of aligned burner openings. In the burner assembly, air-fuel premix is pulled through the premix burner, air is pulled through the cooling air box to cool the premix burner, and flames are projected from each of the burner openings of the burner face assembly for transferring heat within the warm air furnace.

Abstract: A system in accordance with the invention includes a thermo-electric device that is physically proximate with a thermal energy source, where, in operation, the thermo-electric device generates a voltage potential. The system further includes a power conversion circuit connected with the thermo-electric device, to modify the generated voltage potential. Also included in the system is a controller circuit connected with the power conversion circuit, where the thermo-electric device powers the controller circuit via the power conversion circuit. The system additionally includes a valve-control circuit connected with the controller circuit and the power conversion circuit, such that the thermo-electric device powers the valve control circuit, at least in part, via the power conversion circuit. The system also includes one or more sensing devices connected with the controller circuit.

Abstract: An adjustable length punch set assembly for adjusting the overall length of a punch having a punch driver and punch holder that are axially adjustable relative to each other and retained at least in part within a punch guide sleeve and biased axially with respect thereto by a biasing spring. A locking push button is positioned axially within and accessible through a hole of the punch driver, the push button being moveable between a first position for locking the punch driver with respect to the punch holder to prevent length adjustment by rotation of mutually engageable threaded portions thereof, and a second position allowing relative rotation of the punch driver and punch holder along the mutually engageable threaded portions to effect length adjustment. The push button includes one or more detents formed thereon, the detents being engageable with one or more first detent stop(s) formed in the punch driver and second detent stop(s) formed in the punch holder.

Abstract: A process for making thermoplastic polyimides which involves reacting an aromatic dianhydride with an organic diamine in the presence of a tertiary amine in an inert solvent to form a polyamide acid salt; separating the polyamide acid salt from the solvent; and heating the polyamide acid salt under imidization conditions to form the desired polyimide.