Hardwire a thermostat or provide power to a thermostat without a C-wire

Most thermostats are able to be battery powered. If the user wants to hardwire their thermostat or provide power to a wall powered only thermostat without a C-wire, see the following instructions.

Caution: Some thermostats have different nomenclature for their wires. Always check with the HVAC wiring and thermostat manual.

1. Read the manual for the thermostat. Make sure to read the power requirements. Note the voltage as well as maximum current allowed to power the thermostat. The following table displays the power requirements for Alarm.com Smart Thermostats.
    

   Thermostat Name	Voltage	Current Requirements
   Alarm.com Smart Thermostat (ADC-T3000)	24 VAC	Maximum of 1 amp
   Alarm.com Smart Thermostat (ADC-T2000)	24 VAC	Maximum of 1 amp

    
   Note: For more information about power specifications with other thermostats, refer to the manual or manufacturer.
    
2. Check the wiring diagram for the thermostat. In most common cases (for a 24VAC transformer), one of the wires is attached to the RH (sometimes called R) terminal and the other to the C terminal. For more information about Alarm.com Smart Thermostat wiring, see Alarm.com Smart Thermostat - Wiring and Configuration Guide.

The ADC-T2000 and ADC-T3000 Smart Thermostats can also be powered using a standalone transformer that is separate from the HVAC system. However, if a wall transformer is used to power the thermostat, connect between C and RH. The system must be cool-only when using a wall transformer, as the transformer would wire into the RH and C terminals with the jumper removed. For more information, see Can the thermostat be powered by a standalone transformer (separate from the HVAC system)?.