Abstract: An environmental control system that utilizes the output of a thermostat to estimate the outdoor temperature can be used to eliminate the possibility of condensation on the inside of windows and on the inside of the walls. This is important in homes and buildings that are located in areas where the outdoor temperature gets very low. An acceptable humidity level can be calculated when the outdoor temperature has been determined. Once the acceptable humidity level is calculated, this value can be communicated to the humidistat so the humidity level within the house can then be adjusted accordingly. The humidistat can have the capability to manually override the automatic adjustments, thus giving the operator the flexibility of maintaining the humidity level within the building at a desired level.

Abstract: The present invention describes an apparatus and method for controlling the temperature in a plurality of comfort zones within a house or building. The invention contemplates a series of zone control devices which are selectively opened or closed to allow heating and/or cooling to individual zones. The temperature in each zone is sensed and compared to a preferred setpoint temperature to determine a temperature error for each zone. The respective temperature error signals for each zone are used to determine the zone of greatest thermal error. The zone of greatest thermal error is used to turn the heating/cooling plant on and off. The remaining zone or zones of lesser thermal error have their zone control devices closed or opened, depending upon the temperature error signal for their respective zones. In this manner, all zones are synchronized to the zone of greatest thermal error and to the cycle of the heating/cooling plant.

Abstract: A zone control system uses signals from a plurality of separate zone thermostats to determine the zone of greatest thermal load or demand. Specifically, the on-time of each thermostat signal is integrated with respect to time so that the zone of greatest demand can be determined. The thermostat signal from the zone of greatest demand is used to control a duct damper between that zone and a heating/cooling plant. To synchronize the opening of the other zone duct dampers with the duct damper of the zone of greatest demand, the length of each of the on-periods of the thermostats in the other zones is first converted to the cycle rate of the zone of greatest demand thermostat since the other thermostats are operating at different duty cycles. A microprocessor-based master zone controller uses these converted on-signals to control respective zone duct dampers in the other zones coincident with the start of the thermostat on-period of the zone of greatest demand.

Abstract: An electromechanical thermostat for controlling the on/off cycle of a heating/cooling unit. The thermostat has a temperature sensing element with a variable position according to the sensed temperature. Associated with the sensing element is a switch member that provides on/off signals in response to the position of the sensing element. The thermostat has mechanical heat anticipation to control the generation of the on/off signals. In the preferred embodiment the mechanical heat anticipation is accomplished by a stepper motor which varies the position of either the sensing element or switch member to simulate thermal heat anticipation. The thermostat also has a mechanical structure to reduce or eliminate thermostat droop. Preferably this structure includes a control circuit to detect the duty cycle of the heating/cooling unit and mechanically and automatically adjusts the thermostat set point.

Abstract: A method for improving cooling of a compressor element used in an air conditioning system and having a refrigerant compressor and associated drive motor hermetically sealed in a fluid-tight shell includes the steps of detecting an excessive increase in the temperature of the compressor element, intermittently operating the system during the excessive temperature detection with a superheat of a refrigerant in the system below zero superheat degrees to concurrently allow liquid refrigerant to enter the shell to enhance the cooling of the compressor apparatus by the latent heat of vaporization of the liquid refrigerant and terminating the intermittent operation and the admittance of the liquid refrigerant into the compressor element upon a detection of a desired temperature of operation of the compressor element.

Abstract: A refrigeration system comprises a compressor, a condenser, an evaporator, an accumulator, and an adjustable controllable expansion valve. An electronic control system monitors the value of superheat and accordingly provides an electrical control signal to adjust the controllable expansion valve in order to maintain a set point superheat value. An unfiltered path is provided to ensure expedient response when the system starts operation and when dynamic changes occur. A filtered path is provided to reduce hunting, or oscillations about the set point, of the superheat value during steady state operation.

Abstract: A refrigeration system control method for minimizing off cycle losses in a heating mode of operation includes the steps of closing a valve in a refrigerant line between an indoor coil and an outdoor coil for a first predetermined period of time starting with a deenergization of a compressor and ending before a reenergization of the compressor to retain the refrigerant in the indoor coil and maintaining an energization of an indoor coil fan for a second predetermined time period after the deenergization of the compressor which second time ends before the first time period.

Abstract: A multizone control system utilizes a series of timers to ensure that all of the heat supplied to the system is utilized. Timers are used to control transfer of heat from the temperature modifying plant to the zones. The timers are further arranged to bring "on" additional heat to the heat anticipator of the zone of lower demand thereby tending to synchronize the operation of zones and allow for more efficient supply of the heat exchange medium throughout the areas being controlled.

Abstract: A control system for a refrigeration heat pump having an outdoor coil through which air is blown by a fan for extracting heat from outdoor air with means to defrost the coil periodically has a differential pressure responsive means responding to the differential air pressure across the outdoor coil. A time control means periodically operates the heat pump for a time controlled operation for predetermined time period (such as 90 minutes of elapsed operating time) and measures and stores the value of the differential pressure across the coil at the end of the time period in memory. A control means controls the heat pump between the periodically time controlled operations for normal operations for a total elapsed time operation in a pressure controlled operation until the pressure differential as previously stored occurs at which time a defrost cycle is initiated. Periodically a time controlled operation is initiated to update the pressure stored in the memory.

Abstract: An integrated, closed loop system for controlling the fuel to air ratio in an induced draft combustion chamber which has a control pilot through which a draft is induced so that the fuel to air ratio in the control pilot chamber has a predetermined ratio to the fuel to air ratio in the primary combustion chamber.

Abstract: A two-stage thermostat means for an add-on heat pump installation provides separated control of a furnace and a heat pump. The two-stage thermostat means utilizes a single pole, single throw switch means, and a single pole, double throw switch means to properly stage and control a heat pump and a fossil fueled furnace so that they do not overlap. The control of the temperature of the heated area is independent of any need to connect a circuit between the thermostat in the heated area and any type of thermostat at the heat pump itself.

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: An air conditioning system for providing an air cooling operation during a load phase management shutdown of the air conditioning compressor utilizes a thermally insulated cold water tank for storing chilled water. The water is cooled by a free cooling effect using wet bulb temperature drop of a refrigerant circulating between a secondary coil in a condenser section of the air conditioning system and a heat exchanger in the chilled water tank located below the condenser. The secondary coil in the condenser is cooled by a waterspray which can advantageously be derived from the condensate obtained from the evaporator section during a compressor operation phase of the air conditioning system. The chilled water is supplied to a chilled water coil in an evaporator section to cool the air flow in a chilled water cooling operation when the air conditioning compressor is inoperative during the load management phase of the peak hour of the air conditioning system.

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: A heating system of the type having a combustion chamber with a fuel burner, an inlet for combustion air and an exhaust stack is improved by adding a variable-speed induced draft blower, a flow-restricting stack orifice and a fuel valve sensitive to the exhaust gas flow rate through the stack orifice. The fuel valve turns on at a first predetermined exhaust gas flow rate and turns off at a second predetermined exhaust gas flow rate, which is lower than the first predetermined rate. The fuel valve also supplies fuel at a rate proportional to the exhaust gas flow rate. Sensing of the differential pressure across the stack orifice is used to determine the exhaust gas flow rate.

Abstract: A multistage timer control setback thermostat control system maintaining a normal temperature in a space and during selected time periods a reduced temperature wherein a first stage is a refrigeration heat pump, the operation of which is affected by outdoor temperature, and a second stage is an auxiliary electrical heating source. An outdoor temperature responsive means is connected in the control system to maintain the heat pump energized during the space temperature setback period if the outdoor temperature is below some predetermined value. Additionally, the indoor thermostat has a high limit temperature responsive means for terminating the operation of the heat pump should the space temperature exceed some predetermined value during the space temperature setback period.

Abstract: A clock thermostat apparatus for controlling the temperature in a space at different temperatures depending upon the time period of the time controlled apparatus has a second temperature responsive apparatus responsive to space temperature for determining the pickup time required to bring the temperature of the space back to normal after a period of setback. When the space temperature drops a small amount, the pickup time for bringing the space back to a normal temperature is short; however, during cold weather conditions when the space temperature drops a large amount, a greater pickup time period is scheduled.

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.

Abstract: A control sysem for controlling a plurality of refrigeration compressors has an input circuit for receiving a plurality of control signals from control devices for a plurality of evaporators connected to the refrigeration compressors with means for controlling the control signal of the evaporator having the greatest load to control the total operating capacity of the refrigeration compressors. Each of the input circuits has means for rendering the control signal input ineffective from a particular evaporator when the evaporator is in a defrosting cycle to allow the signal from the evaporator having the greatest load control the operating capacity of the refrigeration compressors.

Abstract: A filter condition responsive apparatus for a range or stove vent system containing a first filter for filtering grease and a second series connected filter for the removal of odors. A first pressure responsive device responds to the pressure drop across the grease filter to provide an output indicative of the collection of grease on the filter. A second pressure responsive device responds to the pressure drop across the second filter to provide an output indicative of the flow of air through the filter. The output of the two devices are connected to provide an indication of the condition of the grease filter independent of any change in air flow.