Abstract: HVAC systems and methods are shown which use volumetric air flow and static pressure calculations that correct for different air densities encountered at different altitudes. With respect to the volumetric airflow rate, the systems and methods disclosed herein adjust the calculation of airflow rate to better match the BTU content of de-rated natural gas used at higher elevations, and therefore they are usable in HVAC systems that combust natural gas. The adjusted static pressure calculations may be used in any type of HVAC system.

Abstract: HVAC systems and methods are shown which use volumetric air flow and static pressure calculations that correct for different air densities encountered at different altitudes. With respect to the volumetric airflow rate, the systems and methods disclosed herein adjust the calculation of airflow rate to better match the BTU content of de-rated natural gas used at higher elevations, and therefore they are usable in HVAC systems that combust natural gas. The adjusted static pressure calculations may be used in any type of HVAC system.

Abstract: A motor starting apparatus (10) includes a motor starting relay (112) to switch a motor starting capacitor (110) into a motor circuit across a run capacitor (111). The system control (116) includes an electronic voltage measurement circuit to measure a winding voltage (113, 114) of the motor winding (102, 103). The system control (116) also includes a microprocessor to run an algorithm that causes the system control to switch the starting capacitor (110) out of the motor circuit when a measured winding voltage (113, 114) exceeds a winding voltage threshold.

Abstract: An electric heater is provided with an identifying resistor associated with a connection between the heater and a fan control. When the electric heater is connected to the control, the identifying resistor provides information with regard to the capacity of the particular electric heater that is being attached to the control. The control then utilizes this particular capacity to control both the electric heater and an associated fan motor.

Abstract: A motor starting apparatus (10) includes a motor starting relay (112) to switch a motor starting capacitor (110) into a motor circuit across a run capacitor (111). The system control (116) includes an electronic voltage measurement circuit to measure a winding voltage (113, 114) of the motor winding (102, 103). The system control (116) also includes a microprocessor to run an algorithm that causes the system control to switch the starting capacitor (110) out of the motor circuit when a measured winding voltage (113, 114) exceeds a winding voltage threshold.

Abstract: An electric heater is provided with an identifying resistor associated with a connection between the heater and a fan control. When the electric heater is connected to the control, the identifying resistor provides information with regard to the capacity of the particular electric heater that is being attached to the control. The control then utilizes this particular capacity to control both the electric heater and an associated fan motor.

Abstract: A heat pump having an indoor coil that operates as a condenser when the system is in a heating mode and an outdoor coil that operates as an evaporator when the system is in the heating mode. A variable speed indoor fan is used to move supply air over the indoor coil and a temperature sensor is arranged to provide ambient outdoor temperature data to a programmable computer. The computer contains a schedule for continuously adjusting the speed of the indoor fan in response to changes in the ambient temperature so as to maintain the temperature of the supply air at a constant level. In doing so, the compressor discharge pressure is also maintained within allowable limits and is held substantially constant.

Abstract: An apparatus and method for a heat pump operating in the heating mode controls the condenser air flow rate and the condenser exiting air temperature depending in a first embodiment on the evaporator ambient temperature, and in a second embodiment, the evaporator air temperature and alternatively the condenser air flow rate or the condenser exiting air temperature, to alleviate a cold blow condition. The apparatus and method operate by sensing the evaporator ambient temperature with a sensor positioned proximate to the evaporator, and when that temperature is below a threshold value indicating a cold blow situation, determining by circuit means a modified condenser air flow rate to achieve at the same time a slower air flow and a higher air temperature, so that the cold blow condition is terminated or at least alleviated.

Abstract: An air conditioner or heat pump system is equipped with a thermostat control which includes a temperature sensor and a humidity sensor and an algorithm to control the low voltage signals to the indoor blower section and the compressor to control operation of each in response to the indoor temperature and humidity conditions and the desired temperature and humidity setpoints.

Abstract: In an outdoor unit of a heat pump having a variable speed compressor, the fan speed is controlled in response to both the speed of the compressor and the temperature of the outdoor refrigerant such that the operating efficiency of the fan and its driving motor can be optimized over a full range of compressor operating speeds.