A device for reclaiming waste heat from cooking appliances. The device includes a baffle through which exhaust from the cooking appliance flows, an inlet for receiving exhaust from the cooking appliance, and an outlet for venting exhaust to the atmosphere outside the building or vehicle in which the cooking appliance is located. The baffle extracts heat from the exhaust as the exhaust flows therethrough. The baffle is in thermal communication with a heat sink that directs the extracted heat to the building or vehicle spaces to be heated. The heat reclamation device has a generally thin profile so that the device may be installed above and behind the work surface of the cooking appliance so as to consume a minimal amount of space while not interfering with the normal use of the appliance. The heat reclamation device has means to vent the exhaust directly to the atmosphere, bypassing the baffle.

Heat reclamation device

A drive circuit including a motor for positioning a damper from a rest position to a stalled position and protect the drive mechanism from damage due to increased current to the drive motor when the damper stalls by including a current limiter to prevent the current in the motor from exceeding a predetermined value.

Circuit using current limiting to reduce power consumption of actuator with DC brush motor

Method and apparatus for regulating the flue draft in heating systems including a combustion volume, a flue communicating with the combustion volume, and a vent opening between heated ambient air and the flue, the regulation being accomplished by sensing the flow of air through the vent into the flue, and modulating the setting of a downstream damper to maintain such flow at a predetermined, positive but minimal value. A particularly preferred embodiment includes a temperature sensor positioned at the flue side of the vent and connected to a control system to maintain the damper at such a position that the temperature at such location is at a predetermined value above that of the ambient air temperature, and thus indicative of flow of ambient air into the flue at minimal values approaching incipient spillage of combustion gases at the vent.

Method and apparatus for regulating flue draft

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. The circuit provides for additional safety in that normal operation of the gas valve control apparatus does not take place if the normally open or normally closed end switches stick in either position.

Furnace stack damper control apparatus

An HVAC actuator (10), such as a spring return actuator, may adjust the maximum output torque of the motor (12) with the varying spring return force of the HVAC actuator as the HVAC actuator moves through its range of motion (32). In some cases, this may provide a more constant force at the output of the HVAC actuator and reduce the force that is applied through the motor, drive train (14) and/or the HVAC component (16) when an end stop (28, 30) is reached. Also, an HVAC actuator is disclosed that can be configured to discover and store the location of one or more end stop(s), and to slow the speed of the motor down before the end stop(s) is reached. This may reduce the force that is applied through the motor, drive train and/or the HVAC component when an end stop is reached.

Hvac actuator with output torque compensation

An automatic vent damper for combustion devices such as furnaces which closes the combustion chamber exhaust vent when the furnace burner is off to conserve heat and prevent backdrafts. A damper blade pivotally mounted in the exhaust vent is closed by an electrically-operated damper motor operating against a torsional spring urging the damper plate into the open position, the damper motor being energized whenever burner operation is not in demand by the automatic controls. When the controls call for burner operation, the motor is deenergized and the damper blade moves to the open position under the influence of the torsional spring. A limit switch senses the damper blade achieving the open position and enables burner operation. An electrically conductive, thermally fusible link is positioned within the vent in series with the power supply for the control circuit powering the damper motor and burner controls so that in the event a failure results in burner operation with the damper blade closed, the fusible link melts and thereby deenergizes the damper motor and burner controls allowing the torsional spring to move the damper blade to the open position. The damper blade and actuator components are mounted on a cast iron housing mating with the vent ducts to prevent corrosion or temperature-induced distortions from jamming the damper blade, providing reliable operation over extended periods. A solid state relay or delay switching device is alternatively utilized to control energization of the damper motor to insure reliable operation.

Emanuel Feinberg

Papers

Automatic vent damper