HVAC control system with user interface provided by a mobile wireless device

A forced air furnace comprising:

• a furnace housing;
• the furnace housing coupled to a return air duct for receiving return air from a living space of a building and a supply duct for providing conditioned air to the living space of the building;
• a burner situated inside of the furnace housing;
• a heat exchanger situated inside of the furnace housing and thermally coupled to the burner;
• a blower situated inside of the furnace housing for providing air across the heat exchanger;
• a gas valve for providing gas to the burner;
• and
• a controller situated inside of the furnace housing and operatively coupled to the gas valve and the blower, the controller including an input for receiving a temperature value from a remote temperature sensor that is separate from a thermostat and that is located within the living space of the building as well as for receiving a temperature sensor value from a return air temperature sensor that is for detecting a measure related to temperature of the return air in the return air duct, the controller configured to control the gas valve and the blower based at least in part on the received temperature value and a stored temperature setpoint when the controller input receives the temperature value from the remote temperature sensor and the controller is configured to control the gas valve and the blower based at least in part on the temperature sensor value received from the return air temperature sensor when the temperature sensor value is not received from the remote temperature sensor.

An HVAC controller for controlling an HVAC system of a building, wherein the HVAC system includes a supply air duct and a return air duct, the HVAC controller comprising:

• a communication module for wirelessly receiving a sensed temperature from a remote wireless sensor that is separate from a thermostat and that is located in a living space of the building;
• the communication module also configured to receive a wired connection to a return air sensor configured to detect a return air temperature of the air in the return air duct;
• a controller operatively coupled to the communication module, the controller configured to:
• control the HVAC system based at least in part on the sensed temperature from the remote wireless sensor when the communication module receives the sensed temperature from the remote wireless sensor;
• control the HVAC system based at least in part on the return air temperature when the communication module does not receive the sensed temperature from the remote wireless sensor;
• and
• the communication module is also configured to receive a wired connection to a local user interface for changing a setpoint of the controller.