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: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

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: An HVAC system has at least one variable speed controller for an AC induction motor, especially of the Permanent Split Capacitor (PSC) type. The variable speed controller provides switched power via a modulating triac to the main coils of the motor and constant power via an on/off triac to the auxiliary coils during operation. A large value capacitor is placed in line with the auxiliary coils to reduce power consumption and current draw over that of known systems. Power to the motor can be turned off to provide for motor speed sensing through monitoring the frequency of a generated voltage when the power is turned off. Frequency-based motor speed sensing is accomplished by shutting off all current to the motor and measuring zero crossings on the generated voltage of the decaying magnetic field. The controller can be easily retrofitted onto existing motors. An optional controller bypass is provided to run the motor at rated speed in case of controller failure.

Abstract: A power supply to supply power to a secondary system. The power supply is adapted to receive power from a plurality of primary systems. The power supply having a first rectifier which supplies power to the secondary system from a first primary system. At least one isolated rectifier which is connected to a primary system other than the first primary system. Wherein the primary system other than the first primary system provides power to the isolated rectifier. A power supply means connected to the first rectifier and the isolated rectifier. Wherein the rectifier and the isolated rectifier provide power to the power supply and the power supply provides power to the secondary system. Wherein due to the characteristic of the isolated rectifier, it is not possible to connect the first primary system out of phase with the primary system other than the first primary system, thereby eliminating unsafe voltages.

Abstract: A thermostat having a temporary "now" and "next" functions. The temporary "next" function allows the user to program a temporary deviation from a preprogrammed schedule used to control the temperature within a space. The combination temporary "now" and "next" function allows a user to temporarily set a current setpoint which will be held until a temporary next setpoint becomes the control setpoint, after which the thermostat returns to the preprogrammed setpoints.

Abstract: A low temperature limit for battery powered thermostats for energizing and de-energizing the heating system when the battery can no longer operate the thermostat. The thermostat comprises a battery powered thermostat control for energizing and de-energizing the heating system and a low temperature limit electrically connected in parallel with the battery powered thermostat control. The battery powered thermostat control disables a controllable switch and, thereby, the low temperature limit bimetal switch when the battery is charged. When the battery is discharged, it enables the low temperature bimetal switch limit. Thereby, when the thermostat is no longer operational, the low temperature limit energizes the heating system when the ambient temperature present on the thermostat is below a preselected temperature.

Abstract: A thermostat providing external communication comprising two microprocessors. One microprocessor may be dedicated to the external communication while the other microprocessor runs the application programming. The thermostat is separated into a thermostat housing and subbase. One microprocessor may be located within the thermostat housing with the other located within the subbase. This allows for changing the applications programming through replacement either the housing or the subbase. Replacement of only one portion of the thermostat is cheaper and can be easier.

Abstract: A thermostat which includes a transceiver for receiving and sending communications externally of the thermostat. A thermostat receiving external communications from another thermostat includes an external temperature responsive portion to modify the setpoint of the receiving thermostat based on the information received by the receiving thermostat.

Abstract: A control circuit for a fuel valve in a gas fired furnace controlled by an electronic thermostat is disclosed. The thermostat requires a load current to properly operate, and a pickup and hold circuit along with a time delay circuit are integrated to control a load current circuit to provide the correct load current for the thermostat.

Abstract: The servo apparatus includes a series resistor string connected in parallel with the body of the servo slidewire resistor. Upscale and downscale travel limit voltage points, corresponding to upscale and downscale travel limit positions for the slidewire contact, are established along the resistor string. The limit voltages on the limit voltage points are separately compared with the slidewire contact voltage, and appropriate motor drive signal interrupting signals are produced when the slidewire contact voltage exceeds the upscale limit voltage or drops below the downscale limit voltage. The interrupting signals effect their motor drive signal interrupting action by reversing the output polarity of motor drive comparators which produce the motor drive signals under the control of an error amplifier which compares the apparatus input voltage to the slidewire contact voltage.