Which types of HVAC systems is the Alarm.com Smart Thermostat compatible with?

Which systems are compatible with the Alarm.com Smart Thermostat?

The Alarm.com Smart Thermostat is compatible with both heat pump systems and conventional (normal) systems.

Examples of heat pump systems include:

  • Air source heat pump
  • Geothermal heat pump

Examples of conventional (normal) systems include:

  • Furnaces
  • Boilers
  • Steam and hot water radiators
  • Radiant (in-floor heating)

Does the Alarm.com Smart Thermostat support multistage systems?

Yes. The Alarm.com Smart Thermostat is compatible with up to three stages of heating and two stages of cooling.

What is a multistage system?

Multistage systems use more than one level of heating or cooling (e.g., high, medium, and low) to save energy and keep the house at a more constant temperature. Set the temperature, and the system automatically adjusts the level of heating or cooling. The system will use the lowest level needed to arrive at the right temperature.

Single-stage systems have only one level of heating or cooling, and need to turn on and off much more frequently to maintain a constant temperature. This uses more energy than multistage systems, and also results in more temperature fluctuation.

How do I tell if I have a multistage system?

Check the number of heating and cooling wires attached to your old thermostat by removing the cover (do not disconnect the wires) and look for the letters and numbers found where the wires are connected to the thermostat. Heating wires are commonly labeled with a W, W2, etc. (and are often white) and cooling wires are commonly labeled with a Y, Y2, etc. (and are often yellow). If there is more than one wire for heating or cooling, then the system is a multistage system.

Example: A three-stage heat system can have three white W wires (labeled W1, W2 and W3). A two-stage cooling or heat pump system can have two yellow Y wires (labeled Y1 and Y2).

Is a multistage system the same thing as a multi-zone system?

No. A system can have multiple zones without having multiple stages, and the other way around.

Does the Smart Thermostat support systems with multiple zones?

Yes, the Smart Thermostat supports systems with more than one zone. Each zone can be controlled by its own Smart Thermostat. The Smart Thermostat is compatible with other Z-Wave thermostats. However, the system will work best and most efficiently if all thermostats in the house are replaced with Smart Thermostats.

What is a multi-zoned system?

An HVAC system that has multiple zones means that different areas of the home can be heated or cooled separately. This can be done using separate thermostats for each zone, or by using a damper in the ductwork to direct hot or cool air to the selected zone.

Can the Smart Thermostat control variable-speed HVAC systems?

The Smart Thermostat can control many variable-speed HVAC systems that use standard 24-volt wiring (e.g., with R, G, Y, W, C wiring).

What is a variable-speed system?

Variable-speed systems change the fan speed to push more or less hot or cooled air through the vents. Many of these systems also use multiple stages to allow variable heating and cooling speeds.

Are some variable-speed systems incompatible with the Smart Thermostat?

Some variable-speed HVAC systems use proprietary communication between the thermostat and the main HVAC system to enable variable-speed control. Systems like these require a thermostat made by the same manufacturer as the main HVAC unit to fully access their features.

For help to determine whether a particular variable-speed system is compatible with the Smart Thermostat, contact a local HVAC professional for help.

Can the Smart Thermostat control my home’s humidifier or dehumidifier?


My system has an external air baffle for fresh air. Can the Smart Thermostat work with my system?

The Smart Thermostat works with HVAC systems that have an external air baffle, where the central HVAC system programming controls the baffle.

Some systems rely on the thermostat itself (not the central HVAC system) to control the baffle. The Smart Thermostat will be able to support these systems using the Z terminal. This feature will be made available in the future by a firmware update.

What can the Z terminal on the Smart Thermostat be used to control?

The Z terminal of the Smart Thermostat can currently control:

  • A third heating stage.
  • Humidifier.
  • Dehumidifier.
  • O/B zoning on heat pump systems with both an O and B wire for the ADC-T2000. This option is not available on the ADC-T3000 due to its separate O and B terminals.
    • On the ADC-T2000, the O wire would go into the O/B terminal and the B wire would go into the Z terminal.

Important: If the Z terminal is being used to control one of the preceding features, the Z terminal must be configured using the Partner Portal or MobileTech app to allow control.