Abstract: An HVAC system includes a variable speed electric motor driven fan for circulating air to an enclosed space through an indoor unit for providing heating or cooling effect to air circulated through the indoor unit. A controller with user or system installer actuatable switches includes a programmable microcontroller providing a pulse width modulated (PWM) signal to a motor control unit to select a predetermined air flowrate less than full air flowrate during system startup and shutdown. User input parameters include selected percentages of full air flowrate to satisfy requirements for reduced noise level, lower humidity and for improved sensible heating of air being circulated, the latter being effective particularly for heat pump applications. Selection of pre-run, short run and shutdown cycles may be provided.

Abstract: A controller and method for operating an HVAC system including an air conditioning unit, such as a gas furnace, having three stages of heat output and responsive to signals from a single stage or two stage thermostat. The W1, W2, and W3 inputs to the controller may be configured for receipt of a single stage control signal simultaneously or paired as W1, W2 or W2, W3. The system controller is configured to determine which input connection arrangement is in existence and operates the system in mock one stage or mock two stage modes depending on the signals received from a single or two stage thermostat, respectively.

Abstract: An air conditioning (HVAC) system for a residential dwelling or other building with enclosed spaces includes multiple thermostats hard wire interconnected or communicating via radio frequency transceivers. The thermostats each include control circuits for adjusting the setpoint temperature at any one thermostat and displaying the set temperature at all thermostats, setting the time at any one thermostat and displaying the time at all thermostats, controlling the thermostat temperature setting from a selected one of the thermostats and providing a setpoint for control of the air conditioning system based on an average temperature sensed by all of the thermostats. A method for correctly setting a thermostat time display to one of Daylight Saving Time or Standard Time and displaying an icon identifying one or the other is disclosed.

Abstract: A multistage furnace for heating residential or commercial spaces is operated by a single stage thermostat and a return air temperature sensor providing sensed temperature information to a controller. The furnace is started at a first, low firing rate and after a predetermined time is increased to a second firing rate if the rate of change of temperature of air returning to the furnace from the space is less than a predetermined amount. The method of operation is carried further to increase the firing rate to second and third rates based on predetermined rates of temperature change of return air from the enclosed space as sensed by the return air sensor.