Will a Smart Thermostat Work with My Heating and Cooling System?


Everything seems to be getting smarter! This technological revolution has also reached the way we control our home’s heating and cooling. Today’s smart thermostats can offer a wide range of features and connectivity with a smartphone, making it even easier to align your lifestyle with the comfort of your home.  However, will a new smart thermostat connect with your current heating and cooling system?  

Depending on the HVAC system in your home, it is possible that only a specific style of thermostat or control system may control the system’s functions. It often comes down to what type of heating and cooling equipment was installed and the specific wiring that is required between your equipment and the thermostat.

Your Heating and Cooling Equipment

Traditional HVAC systems were not designed to communicate with the various types of smart technology on the market today. It’s even possible that your specific HVAC system will only operate as designed with one specific style of thermostat or HVAC control system installed on the wall. This is why you often have to purchase a new thermostat at the same time as a new HVAC system. 

Traditionally, heat pumps, gas furnaces, air conditioners, and air handlers operations are controlled by the thermostats or HVAC control systems that can address their unique features.

For example:

  • If your home has a heat pump, the thermostat must be able to identify the auxiliary heat function. If it a thermostat is specific to a gas furnace, you may not be able to control this additional function.
  • A dual fuel system, which is comprised of a gas furnace and a heat pump, should be connected to a thermostat that can accommodate the specific heating set points to transfer the heating duties.
  • A high-efficiency, two-stage or variable speed system would traditionally be connected to a thermostat that could adjust operation based on the demand. This type of system required the thermostat to have two-stage wiring. (NOTE: New revolutionary HVAC technology is changing this)

If you’re not sure which type of system is installed in your home, it’s best to ask your the license professional HVAC technician.

HVAC Efficiency and Thermostat Compatibility

Thermostat compatibility often depends on the features associated with the HVAC system installed in your home. Some of the terminology used to describe these features may include:

  • Single-stage: Your heating or cooling system operates at 100% capacity until it reaches your preset indoor temperature and then turns off.
  • Two-stage: Your heating or cooling system is capable of operating at 100% capacity and a lower speed, depending on demand.
  • Variable-speed or multi-stage:  Your system offers various levels of output to match the demand.

If you plan to upgrade your current HVAC equipment to a high-efficiency model with two-stage or variable speed features, your current thermostat may not be designed to accommodate the additional energy-efficient features. The communicating technology that allows the certain features of your system to operate as designed is, most likely, located in the thermostat on the wall of your home. 

Don’t miss out on the energy-efficiency benefits of your new high-efficiency HVAC system simply because the thermostat or control system cannot speak the language of your HVAC equipment.

To be sure you are getting the maximum benefit out of your high-efficiency heating and cooling equipment, talk to your licensed professional HVAC technician about thermostat compatibility or the latest communicating high-efficiency heating and cooling equipment.

Thermostat Wires and Power

While you should always hire a licensed professional to work with any wiring in your home, it’s helpful to understand why some thermostats are designed to work with specific equipment. It often comes down to the wiring set-up between the specific HVAC equipment installed and the thermostat on the wall.

The most common types of thermostat or control systems on the market today use low voltage wiring. The wires to low-voltage thermostats or HVAC control systems are typically very thin, similar to wiring for doorbells or telephone jacks.  A low voltage thermostat or control system is commonly used to connect with:

  • Forced-air gas furnaces
  • Single-stage or multi-stage heat pumps
  • Central air conditioning systems with ductwork

Many smart thermostats and HVAC control systems have features, including home automation options, which require it to be powered at all times by a ‘common’ wire (C-wire). The common wire supplies constant power to your connected thermostat. If your home’s current set up doesn’t allow for constant power through a dedicated C-wire, a licensed professional HVAC technician may need to add the specific wiring for these home automation options to work properly.

To determine your specific home set up, consult with your licensed professional HVAC technician.

New HVAC System Technology

Historically, premium heating and cooling systems have limited homeowners to one specific, and perhaps expensive, smart thermostat or HVAC control system. However, rather than relying on the communicating technology in the thermostat on the wall, innovative manufacturers are factory-installing smart technology directly into the indoor HVAC equipment. This built-in technology is designed to actively learn and make continuous automatic adjustments to the equipment’s operation, as needed, based on the homeowner’s set preferences.

With this technology added directly to the HVAC equipment, a homeowner may have the opportunity to keep their current single-stage thermostat or choose from a wide assortment of thermostat or control systems on the market. 

If you are considering upgrading your HVAC equipment or simply the thermostat or control system, it is best to seek the guidance of a licensed professional HVAC dealer.  They should be able to assess the technology of your current indoor comfort equipment and determine which thermostat or control system is compatible.

Smart Thermostat and HVAC Compatibility