Abstract: Process and device for improving of synthesis and/or flue gas velocity field solves technical problem of local increase of velocity and resulting non-homogeneous flue gas field resulting in uneven temperature and concentration distribution within flue gas field by providing for homogenization of flue gas field using strategically placed obstacles in the flow field such as flaps or similar devices.

Abstract: A blower has a blower housing of clamshell construction, including two housing members having a scroll back wall molded with radial draft, an impeller and a motor within the housing, and a static tap connected to the housing. The impeller has a backplate with a backplate back surface region of substantially the same radially converging shape as that of a front surface region of the scroll back wall formed by the radial draft, providing a substantially uniform axial gap between the backplate back surface region and the scroll back wall. The impeller has a ring connected by a skirt to the back plate to define a stepped area behind the ring. The impeller includes impeller blades extending forwardly from the impeller backplate and the ring and back fins extending rearwardly from the ring. The blower has a scroll width of about twice an impeller exhaust width.

Abstract: A hot water device includes a heat exchanger and an apparatus to which the heat exchanger is to be connected. First and second cases for the heat exchanger and the apparatus to which the heat exchanger is to be connected include first and second flange portions laid over each other and welded together. The first and second flange portions are each demarcated into a corner flange portion corresponding to one of first and second corner portions, and into a non-corner flange portion other than the corner flange portion. The non-corner flange portions protrude more to the outside of the first and second cases than the corner flange portions.

Abstract: A blower has a blower housing of clamshell construction, including two housing members having a scroll back wall molded with radial draft, an impeller and a motor within the housing, and a static tap connected to the housing. The impeller has a backplate with a backplate back surface region of substantially the same radially converging shape as that of a front surface region of the scroll back wall formed by the radial draft, providing a substantially uniform axial gap between the backplate back surface region and the scroll back wall. The impeller has a ring connected by a skirt to the back plate to define a stepped area behind the ring. The impeller includes impeller blades extending forwardly from the impeller backplate and the ring and back fins extending rearwardly from the ring. The blower has a scroll width of about twice an impeller exhaust width.

Abstract: A draft inducer blower assembly for use with a water heater has a housing, a motor, and a fan. The housing has an exhaust volute surrounding the fan and a base adapted to be mounted atop a water heater. The base has an inlet port adapted to receive exhaust gas from the water heater. The fan is connected to the motor for rotation about a rotation axis. The exhaust volute and the base are non-adjustably fixed relative to each other. The exhaust volute has a cut-off at a cut-off angle relative to the rotation axis. The exhaust volute has an exhaust outlet passageway that extends to an exhaust port. The exhaust port is lower than the top of the exhaust volute.

Abstract: A draft inducer blower assembly for use with a water heater has a housing, a motor, and a fan. The housing has an exhaust volute surrounding the fan and a base adapted to be mounted atop a water heater. The base has an inlet port adapted to receive exhaust gas from the water heater. The fan is connected to the motor for rotation about a rotation axis. The exhaust volute and the base are non-adjustably fixed relative to each other. The exhaust volute has a cut-off at a cut-off angle relative to the rotation axis. The cut-off angle extends at an angle that is no more than twenty degrees positive from horizontal. The exhaust volute has an exhaust outlet passageway that extends to an exhaust port. The exhaust outlet passageway extends beneath the cut-off before reaching the exhaust port.

Abstract: A fume exhaust assembly and a fume exhaust device are provided. The fume exhaust assembly includes a fan, a vortex generating portion, a fume intake pipe, and a fume exhaust pipe. The vortex generating portion includes a vortex pipe and an air intake channel. The air intake channel is in communication with the vortex pipe, an inlet of the air intake channel is connected to the fan, and an outlet of the air intake channel is configured to generate a vortex updraft in the vortex pipe. The fume intake pipe and the fume exhaust pipe are in communication with the vortex pipe. An outlet of the fume intake pipe is arranged above the outlet of the air intake channel. The outlet of the fume intake pipe is configured to be in communication with a low-pressure zone of the vortex updraft. The fume exhaust pipe is connected to an outlet of the vortex pipe.

Abstract: Systems and methods for controlling an exhaust gas fan system. The control system may control one or more components of the exhaust system to optimize system performance and improve energy efficiency. The control system may be designed to maintain a substantially constant pressure in the exhaust header and provide a substantially constant flow through the exhaust fans. The control system may include software and hardware that allow the control system to control one or more of: modulation of one or more by-pass dampers; adjustment of the nozzle outlet area; varying the speed of the fans; the number and staging of fans. By utilizing and controlling one or more of these functions, the amount of energy being used may be minimized/optimized.

Abstract: A rotor includes a yoke, an end cap, and a rotary shaft. The yoke is fixed relative to the end cap. The rotary shaft extends into the yoke. One end of the rotary shaft is connected to the end cap. The end cap is formed on the yoke and the rotary shaft by injection molding. The present invention further provides a motor and an electric tool including the rotor. In the rotor of this invention, the end cap is formed by injection molding, and the yoke and the rotary shaft are connected into a whole at the same time of forming the end cap. The traditional aluminium end cap is replaced with the molded end cap, which makes the rotor easier to fabricate and have a lighter weight and lower cost.

Abstract: A method and apparatus of reducing thermal shock in one or more radiant tubes of a pyrolysis furnace is provided. The apparatus is a furnace comprising a blower and blower bypass conduit providing separate fluid communication paths for flue gas from the convection section to a natural draft flue gas stack. The method comprises the steps of: redirecting at least a portion of the flue gas through the blower bypass conduit when a blower shut-off event is indicated as well as reducing the firing rate of the furnace.

Abstract: A furnace inducer choke and a gas furnace employing the furnace inducer choke. In one embodiment, the furnace inducer choke includes: (1) a choke body configured to engage a furnace inducer blower, the choke body having an opening extending entirely therethrough to limit an amount of combustion air entering a furnace that the furnace inducer blower is attached, and (2) a tab protruding from the choke body a distance sufficient to identify the opening when the choke body and furnace inducer blower are installed in the furnace.

Abstract: Techniques for controlling a solid fuel combustion appliance, e.g., a wood burning stove, are disclosed. A control system measures an exhaust gas temperature of airflow through an outlet of the solid fuel combustion appliance. The control system determines a derivative of the exhaust gas temperature with respect to time. The derivative of the exhaust gas temperature with respect to time is compared to a predetermined threshold. The control system modulates the inlet damper in response to determining that the derivative of the exhaust gas temperature with respect to time reaches the predetermined threshold.

Abstract: A furnace system includes at least one lower radiant section having a first firebox disposed therein and at least one upper radiant section disposed above the at least one lower radiant section. The at least one upper radiant section has a second firebox disposed therein. The furnace system further includes at least one convection section disposed above the at least one upper radiant section and an exhaust corridor defined by the first firebox, the second firebox, and the at least one convection section. Arrangement of the at least one upper radiant section above the at least one lower radiant section reduces an area required for construction of the furnace system.

Abstract: A method and apparatus of reducing thermal shock in one or more radiant tubes of a pyrolysis furnace is provided. The apparatus is a furnace comprising a blower and blower bypass conduit providing separate fluid communication paths for flue gas from the convection section to a natural draft flue gas stack. The method comprises the steps of: redirecting at least a portion of the flue gas through the blower bypass conduit when a blower shut-off event is indicated as well as reducing the firing rate of the furnace.

Abstract: A heat exchanger comprising a heat exchange unit in which heat is exchanged between combustion gas caused by a burner for combusting a mixture and first/second heating mediums, and heating medium flow channels through which the first/second heating mediums flow and a combustion gas flow channel through which the combustion gas flows are alternately formed adjacent to each other in spaces between a plurality of plates and a combustion gas discharge unit through which the combustion gas having passed through the heat exchange unit is discharged is provided.

Abstract: The invention provides a motor-driven chimney draft system with a flue gas inlet, a flue gas outlet, a flue gas compartment in fluid communication with the flue gas inlet and with the flue gas outlet, the flow of flue gases in the flue gas compartment having a flow direction from the flue gas inlet to the flue gas outlet, a motor compartment with motor having a motor shaft extending through a separating wall of the flue gas compartment, the motor shaft carrying an impeller for driving the received flow of flue gases in the flow direction; each of the separating wall of the flue gas compartment and the separating wall of the motor compartment extends parallel to the flow direction of flue gases, and they are arranged facing each other so as to define an air space therebetween, where the air space has openings allowing ambient air to flow through the air space.

Abstract: A furnace inducer choke and a gas furnace employing the furnace inducer choke. In one embodiment, the furnace inducer choke includes: (1) a choke body configured to engage a furnace inducer blower, the choke body having an opening extending entirely therethrough to limit an amount of combustion air entering a furnace that the furnace inducer blower is attached, and (2) a tab protruding from the choke body a distance sufficient to identify the opening when the choke body and furnace inducer blower are installed in the furnace.

Abstract: A furnace assembly comprising a non-condensing furnace with a draft inducer. The draft inducer includes a permanent magnet electrically commutated motor and a draft inducer blower fan. The motor includes a stator, a rotor, a motor cooling fan, and a controller. The rotor being rotatable relative to the stator, the fan being operatively coupled to the rotor such that rotation of the rotor causes rotation of the fan, the controller being configured to selectively operate the motor in first and second different torque ranges of the rotor, with the first and second torque range operating within a fixed percentage and within a fixed percentage of each other. The controller being configured such during normal operation, the motor is not operable at any torques between the first torque range and the second torque range except during transitionary periods.

Abstract: A wood pellet stove operable to mount to a wall includes a combustion chamber, a combustion chamber door, and a hopper. The combustion chamber has a front, back, and side. The combustion chamber door is in the front of the combustion chamber. The hopper is mounted at the side of the combustion chamber. The bottom of the hopper is below a top of the combustion chamber, and a top of the hopper is substantially coplanar with the top of the combustion chamber. The stove may also include a sight glass or fuel level monitoring system for determining a fuel level of the hopper without opening the hopper.

Abstract: The combination of a vent assembly with a conduit assembly bounding a flow space into which discharged combustion gases are exhausted. The conduit assembly has a first conduit length in which: a) combustion gases are communicated in a first direction in a first path between the flue outlet and a vent outlet; and b) backflow is communicated in the first path in a direction opposite to the first direction. The conduit assembly has a draft control assembly, with a conduit portion defining a flow passage in which backflow is diverted out of the first path. The draft control assembly further has a flow guide assembly that intercepts and guidingly diverts the backflow into the conduit portion to be exhausted.

Abstract: An exhaust fan assembly is provided for expelling contaminated air from a building. The assembly includes a plenum, a fan assembly attached to the plenum, and a windband mounted on top of the fan assembly. The fan assembly is constructed of cylindrical outer and inner walls which define a bearing chamber and surrounding annular space. A fan driven by a shaft extending downward from the bearing chamber draws exhaust air from the plenum and blows it up through the annular space to a nozzle at the top of the fan assembly.

Abstract: An exhaust system for expelling air from a building includes an outlet nozzle that improves entrainment of ambient air with the building exhaust air. The improved air entrainment results in increased exhaust air dilution and plume height to better disperse the exhaust air away from the building. The nozzle has an H-shaped outlet configuration with two lateral outlet sections joined by a central transverse outlet section. The nozzle has a pair of outer lateral walls, a pair of outer transverse walls, and a pair of sloped inner lateral walls that angle outwards from near an inlet end of the nozzle towards corresponding outer lateral walls. The nozzle can be part of the exhaust system at the outlet side of the exhaust fan within a windband that aids in entraining ambient air with the exhaust air exiting the nozzle.

Abstract: A baking oven and a method for controlling the exhaust flow from a cooking chamber of the baking oven, the flow being discharged by a fan. The method includes increasing a speed of the fan during a first time interval after. A first temperature of the baking oven is measured using a first temperature sensor during the first time interval. At the same time a second temperature of the baking oven is measured using a second temperature sensor. An electronic controller is used to determine the temperature difference between the temperatures during the first time interval. At a selected fan speed, the determined temperature difference varies from an initial temperature difference measured at the beginning of the first time interval. The controller sets at least one of the fan speed and a position of a bypass damper as a function of the selected fan speed.

Abstract: The high velocity and high dilution exhaust system uses a centrifugal fan provided with a tapered nozzle. The nozzle compresses the airstream exiting the fan to increase back pressure and velocity. The air flow from the fan enters a stack having a venturi further increasing the velocity and decreasing the pressure. The decrease in pressure causes a suction, allowing the introduction of ambient air to mix with and dilute the output of the fan. The total discharge from the exhaust stack has a high velocity resulting in a plume height and effective height of the exhaust before dispersion occurs.

Abstract: A furnace blower housing has a two-piece exhaust transition, one piece of which is an integral extension of the blower housing, that transitions a rectangular cross section outlet of the blower housing to a circular cross section outlet of the exhaust transition that is adapted to be attached to a circular exhaust pipe.

Abstract: A gas-exhausting module structure includes a casing having a first open end and a second open end. An air-exhausting channel is defined within the casing. The air-exhausting channel has an upper opening that is lower than the second open end of the casing. A blower comprising a chamber, an air outlet, and an air inlet is provided. The blower is in communication with the air-exhausting channel. The air inlet of the blower is connected to an air-sucking box. When power of the blower is turned on, it sucks air into the air-exhausting channel and expels high-pressure air through the upper opening of the air-exhausting channel.

Abstract: A balanced building ventilation system that employs a fireplace as an element of the ventilation system. The fireplace includes a firebox, and an exhaust gas flue is connected to the firebox for exhausting gas from the firebox to the outdoor ambient. A ventilation channel conveys outdoor ambient air into the building interior. A motor-driven draft inducer is connected to the exhaust gas flue for forcing exhaust gas flow out to the outdoor ambient. A motor-driven blower is provided for forcing ventilation airflow through the channel to replace building interior air lost to exhaust gas flow.

Abstract: A furnace blower housing has a two-piece exhaust transition, one piece of which is an integral extension of the blower housing, that transitions a rectangular cross section outlet of the blower housing to a circular cross section outlet of the exhaust transition that is adapted to be attached to a circular exhaust pipe.

Abstract: A blower for a high efficiency furnace is provided with an increased interior space for accommodating an impeller of maximum practicable diameter. The blower includes a blower motor and a blower housing having a bottom piece and a top piece assembling with the bottom piece to define an interior of the blower housing. The top piece includes an annular lower support portion for supporting the blower motor and an annular upper portion extending above and around the lower portion. The upper portion has an outer peripheral edge and lugs extending outward beyond the outer peripheral edge. The lugs have lug holes to receive mechanical fasteners to secure the blower housing to an external device. The head of the mechanical fasteners are positioned above the lugs on the upper portion of the top piece. In this arrangement the diameter of the bottom piece is not limited by a need to accommodate spacing for the head of the mechanical fastener.

Abstract: A discharge valve plate of the type used in the conduit between an exhauster fan and a riffle box in a coal fine delivery system for a coal-fired combustion chamber in a power plant. The axis of rotation of the discharge valve plate is oriented generally perpendicular to the axis of rotation of the exhauster fan, such that the valve plate bisects the flow of coal fines from the exhauster fan into upper and lower flows, each having heavy and light distributions across the width of the conduit. The discharge valve plate is provided with diffuser elements engaging the upper and lower flows to cause the heavy and light flow distributions to mix prior to reaching the riffle box.

Abstract: A blower for a furnace is provided where the blower has a housing with an industry standard 4″ diameter exhaust port. The discharge of the blower housing is coupled directly to exhaust piping without the use of transition pieces or expender pieces.

Abstract: A variable speed power flue ventilator with a thermostatically controlled motor cooling system. The thermostatically controlled cooling system employs an auxiliary motor cooling fan separate from the fan used by the power ventilator to extract exhaust gases. A thermostatic sensor switch actuates the motor cooling fan whenever the temperature in the exhaust fan motor housing rises to a preset value. The cooling fan then draws cool ambient air through the motor housing until the enclosed housing area reaches a second lower, preset temperature at which point the cooling fan is shut off by the thermostat.

Abstract: A power vented, gas fired water heater has a main gas burner disposed within a combustion chamber partially bounded by an arrestor plate having a spaced series of flame quenching combustion air inlet openings therein. To provide for a “soft” ignition of extraneous flammable vapors entering the combustion chamber and to limit the build-up of unignited flammable vapors within the combustion chamber during non-demand periods of the water heater, a non-flame type ignition device is disposed within the combustion chamber and operated at least intermittently during such non-demand periods.

Abstract: A blower for a high efficiency furnace is provided with an increased interior space for accommodating an impeller of maximum practicable diameter. The blower includes a blower motor and a blower housing having a bottom piece and a top piece assembling with the bottom piece to define an interior of the blower housing. The top piece includes an annular lower support portion for supporting the blower motor and an annular upper portion extending above and around the lower portion. The upper portion has an outer peripheral edge and lugs extending outward beyond the outer peripheral edge. The lugs have lug holes to receive mechanical fasteners to secure the blower housing to an external device. The head of the mechanical fasteners are positioned above the lugs on the upper portion of the top piece. In this arrangement the diameter of the bottom piece is not limited by a need to accommodate spacing for the head of the mechanical fastener.

Abstract: A furnace blower housing has a two-piece exhaust transition, one piece of which is an integral extension of the blower housing, that transitions a rectangular cross section outlet of the blower housing to a circular cross section outlet of the exhaust transition that is adapted to be attached to a circular exhaust pipe.

Abstract: A method for controlling kiln pressure for a shuttle kiln having an exhaust gas fan and an exhaust gas damper in an exhaust gas passage includes the steps of performing a control operation for controlling the number of revolution of the exhaust gas fan to control flow rate of the exhaust gas to maintain the kiln pressure at a predetermined pressure, and performing a control operation for adjusting opening of the exhaust gas damper based on the number of revolution of the exhaust gas fan. The method can expand the control range of exhaust gas flow, and operation with energy saving efficiency can be performed.

Abstract: A woodstove emission controller for conveniently drawing emissions from the wood-stove so that the emissions do not enter the room where the wood-stove is located. The woodstove emission controller includes a tubular member having an inlet end, an outlet end and a bore extending therethrough; and also includes a closure member securely disposed in the bore near the outlet end for preventing a back-draft of emissions; and further includes a fan member securely and rotatably disposed in the bore for drawing emissions in through the inlet end and out through the outlet end of the tubular member; and also includes a motor mounted to the exterior of the tubular member, a belt member carried by the motor and the fan member, and a switch for energizing the motor.

Abstract: A water heater of the invention includes a water container; a combustion chamber adjacent the water container; a burner associated with the combustion chamber; a flue connected to the combustion chamber; a blower assembly positioned to receive combustion products from the flue and convey the combustion products to a remote location; and a pressure switch positioned to detect blockage of combustion products away from the blower assembly and flow of air from the flue prior to initiation of combustion in the combustion chamber.

Abstract: Required blower power in an induced draft combustion system is reduced by recovering pressure from dynamic energy of flow of combustion products. To this end, the outlet duct is diverged gradually, such as an included angle of less than fifteen degrees, and preferably at an angle of substantially seven degrees. Divergence of the outlet duct may be expressed in polar coordinates having a polar axis, overlapping radius vectors and a variable polar angle of such overlapping radius vectors relative to the polar axis. A difference between such overlapping radius vectors is increased in a direction of flow of the combustion products and the outlet duct is structured with cross-sections increasing incrementally in terms of the increasing difference between the overlapping radius vectors. Condensate may be drained from a combustion product by providing the duct with a lateral offset having a bottom extending at an angle to the earth's field of gravity.

Abstract: A blower draws air through an inlet duct from outside a building or dwelling and injects air and fuel into a sealed combustion chamber where they are ignited and burned within a ceramic crucible within combustion chamber. The pressurized combustion gases flow up an exhaust stack in the water tank of the water heater. The exhaust stack is connected to a vent that extends through a building outside wall. The vent is surrounded by the inlet duct which has an opening spaced from the outlet vent so that air from the vent is not captured by the inlet. The combustion chamber and the heat exchanger are sealed from the interior of the building and both the air inlet to the blower and the air outlet from the heat exchanger freely communicate to the outside of the building. A timer within the controller operates the blower for a period of time after the fuel supply to the burner has been shut off.

Abstract: A waste incinerator including separate burning-, blower-, chimney- and ash-receiving chambers. A suction-discharge port is provided in a wall between the burning chamber and the chimney chamber for discharging gases from the burning chamber through a chimney to the atmosphere. The chimney extends from the chimney chamber for discharging gases to the atmosphere. The chimney receives an air feed pipe from the blower and an ignition sleeve extends into the chimney for burning unconsumed waste gas. A vibrator vibrates an ash receiver in the ash receiving chamber, and a drying chamber may be provided for drying high moisture garbage by combustion gases from the burning chamber.

Abstract: A blower fan assembly for removing combusted by-products and flue gas from a furnace is presented. The blower fan assembly includes a housing with a cavity for receiving a blower fan. The housing is secured over an opening in a furnace so that when the blower fan rotates, flue gas is drawn from the furnace to an exhaust conduit outside the building in which the furnace is received. The blower fan includes a fan ring connected to a fan disc by a plurality of vanes which are parallel with the axis of rotation. A motor, mounted to the housing, rotates the fan disc. The blower fan draws air in through the fan ring, through the plurality of vanes and out through the exhaust conduit. A static pressure tap is located in the housing and is connected to a pressure sensor which measures the static pressure generated by the blower fan as it rotates.

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: A water heater includes a tank and an exhaust blower is located below the tank and connected to the exhaust line to draw the combustion products by suction through the coil-shaped heat exchanger, through the combustion gases conduit and through the combustion chamber and to draw fuel and air into the burner through the inlet conduit.

Abstract: A high efficiency furnace having a heat exchanger and an inducer fan housing attached to the flue gases exit of the heat exchanger to draw flue gases out of the exchanger and force the gases out of the furnace under pressure through a venting system. A condensate return channel is provided for directing condensate developed in the vent system back into the inducer housing where it its removed from the furnace by a drain.

Abstract: Systems and methods for controlling a draft inducer for use with a furnace. The draft inducer includes a fan for moving combustion chamber gases for inducing a draft in the furnace combustion chamber that causes a pressure drop across a heat exchanger. The density of the gases flowing across the heat exchanger and the fan differs from a first operating state of the furnace to a second operating state of the furnace. A motor drives the fan in response to a motor control signal so that different motor speeds result as a function of the density of the gases flowing across the fan. A control circuit generates the motor control signal as a function of a first set of speed/torque curves until a speed signal indicates that the motor has reached a predetermined speed. After the speed signal indicates that the motor has reached the predetermined speed, the control circuit generates the motor control signal as a function of a second set of speed/torque curves.

Abstract: A combination damper and chimney cap apparatus is provided to ventilate a fireplace and a flue connected thereto to provide a draft through the flue. The apparatus includes a platform constructed and arranged to be removably mounted to the flue and formed with an aperture extending therethrough in communication with the flue. An element senses temperature-smoke at the flue and at an area external to a fireplace connected to the flue to provide a signal in response to the temperature-smoke. A ventilation fan is connected to the a support to provide a draft sufficient to exhaust the smoke from the fireplace and the flue and to cool a electronic motor for the apparatus.

Abstract: A gas fired furnace system (10) has a controller (14) controlling the supply of gas through a gas valve (12) and air for combustion by means of an induced air draft fan (28), ignition of the gas by means of ignitor (22), the delivery of heated air from a heat exchanger (20) by means of an air blower (34) in response to signals from a thermostat (42). A selected constant flow of air for combustion is provided by controlling the speed of the motor driving the induced motor fan (28) despite changes which may occur in back pressure. Induced draft fan motor parameters proportional to motor torque and motor speed are read on an ongoing basis and inputted to controller (14) which computes a desired voltage and compares that with referenced data stored in the controller memory and makes corrections to the speed of the induced draft fan motor to maintain the constant air flow.

Abstract: A blower for a high efficiency furnace is provided with an increased interior space for accommodating an impeller of maximum practicable diameter. The blower includes a blower motor and a blower housing having a bottom piece and a top piece assembling with the bottom piece to define an interior of the blower housing. The top piece includes an annular lower support portion for supporting the blower motor and an annular upper portion extending above and around the lower portion. The upper portion has an outer peripheral edge and lugs extending outward beyond the outer peripheral edge. The lugs have lug holes to receive mechanical fasteners to secure the blower housing to an external device. The head of the mechanical fasteners are positioned above the lugs on the upper portion of the top piece. In this arrangement the diameter of the bottom piece is not limited by a need to accommodate spacing for the head of the mechanical fastener.