HVAC controller with user-friendly installation features facilitating both do-it-yourself and professional installation scenarios

A method of determining a heating, ventilation, and air conditioning (HVAC) system configuration for an HVAC system for control by a thermostat, the method comprising:

• determining identities of a first subset of a plurality of HVAC connectors into which corresponding HVAC wires have been inserted, wherein the plurality of HVAC connectors are configured to receive a corresponding plurality of HVAC control wires corresponding to the HVAC system;
• identifying, based on said identities of said first subset of HVAC connectors, whether (i) only a single possible HVAC system configuration is indicated thereby, or (ii) multiple possible HVAC system configurations are indicated thereby;
• operating, if said single possible HVAC system configuration is indicated, said HVAC system according to said single possible HVAC system configuration;
• and
• resolving, if said multiple possible HVAC system configurations are indicated, a particular one of the multiple possible HVAC system configurations that is applicable, and operating said HVAC system according to said resolved particular HVAC system configuration, wherein:
• said resolving is performed at least in part by a processing system coupled to a user interface, the processing system being configured to be in operative communication with the HVAC system to control the HVAC system.

A thermostat comprising:

• a processing system
• a power stealing circuit coupled to the processing system and configured to provide power to the user interface using a rechargeable battery;
• a plurality of HVAC connectors configured to receive a corresponding plurality of HVAC control wires;
• a connection sensing module coupled to the plurality of HVAC connectors and configured to provide an indication to the processing system whether a wire is mechanically inserted for each of the plurality of HVAC connectors, wherein the processing system is configured to determine an HVAC system configuration by:
• identifying a subset of the plurality of HVAC connectors into which a wire has been mechanically inserted;
• identifying an ambiguity resulting from the subset;
• resolving the ambiguity resulting from the subset to determine the HVAC system configuration;
• and
• operating the HVAC system in accordance with the HVAC system configuration.