A thermostat for controlling a heating, ventilation, and air conditioning (HVAC) system, the thermostat comprising: a wall mounted unit configured to be mounted on a wall, the wall mounted unit comprising: at least one terminal connector configured to connect to the HVAC system; a first wireless receiver; a wireless recharging circuit configured to recharge a rechargeable battery via an electromagnetic induction path; a Hall effect sensor configured to output a signal to initiate an activation of the wireless recharging circuit; and a detachable dial control unit that is capable of being detached from the wall mounted unit while enabling a user to enter thermostatic information through the detachable dial control unit, the detachable dial control unit comprising: a display; a contact sensing circuit; the rechargeable battery configured to be rechargeable via the electromagnetic induction path; an activation magnet configured to cause, when within a predetermined distance from the Hall effect sensor, the Hall effect sensor to output the signal to initiate the activation of the wireless recharging circuit; an outer ring that is able to rotate, wherein a rotational position is indicative of thermostatic information; a portion of the detachable dial control unit, wherein the thermostatic information is confirmed when the contact sensing circuit detects at least a predetermined degree of contact against the portion; and a first wireless transmitter configured to convey the thermostatic information to the first wireless receiver via a wireless duplex communication channel. a wall mounted unit configured to be mounted on a wall, the wall mounted unit comprising: at least one terminal connector configured to connect to the HVAC system; a first wireless receiver; a wireless recharging circuit configured to recharge a rechargeable battery via an electromagnetic induction path; a Hall effect sensor configured to output a signal to initiate an activation of the wireless recharging circuit; and at least one terminal connector configured to connect to the HVAC system; a first wireless receiver; a wireless recharging circuit configured to recharge a rechargeable battery via an electromagnetic induction path; a Hall effect sensor configured to output a signal to initiate an activation of the wireless recharging circuit; and a detachable dial control unit that is capable of being detached from the wall mounted unit while enabling a user to enter thermostatic information through the detachable dial control unit, the detachable dial control unit comprising: a display; a contact sensing circuit; the rechargeable battery configured to be rechargeable via the electromagnetic induction path; an activation magnet configured to cause, when within a predetermined distance from the Hall effect sensor, the Hall effect sensor to output the signal to initiate the activation of the wireless recharging circuit; an outer ring that is able to rotate, wherein a rotational position is indicative of thermostatic information; a portion of the detachable dial control unit, wherein the thermostatic information is confirmed when the contact sensing circuit detects at least a predetermined degree of contact against the portion; and a first wireless transmitter configured to convey the thermostatic information to the first wireless receiver via a wireless duplex communication channel. a display; a contact sensing circuit; the rechargeable battery configured to be rechargeable via the electromagnetic induction path; an activation magnet configured to cause, when within a predetermined distance from the Hall effect sensor, the Hall effect sensor to output the signal to initiate the activation of the wireless recharging circuit; an outer ring that is able to rotate, wherein a rotational position is indicative of thermostatic information; a portion of the detachable dial control unit, wherein the thermostatic information is confirmed when the contact sensing circuit detects at least a predetermined degree of contact against the portion; and a first wireless transmitter configured to convey the thermostatic information to the first wireless receiver via a wireless duplex communication channel.