Various embodiments include a device comprising: two connectors for powering the device; a controller to operate an HVAC system; a memory; a transponder controller and an antenna for near field communication; and a transponder memory storing a configuration version and an address list. Firmware in the transponder memory includes instructions for the controller to: connect to a handheld device; determine an address thereof; determine whether the address is on the list; if so: receive initial configuration data from the handheld device, and store it in the transponder memory. There is firmware in the device memory telling it to: connect to the transponder controller; read a device version; read the configuration version in the transponder memory; determine whether the configuration version is compatible with the device version; and if so, transfer the initial configuration data to the memory, and thereafter use the initial configuration data in operation of the system.