How do I know if my system has a communicating control system or a 24VAC control system?

There are a few ways to determine what type of control system you have.


  • For air conditioners and heat pumps

If you have one of the following brands it is most likely a communicating system and a brand Adapter Kit will be required.

Daikin, Fujitsu, Hitachi, LG, Midea, Mitsubishi Electric, Mitsubishi Heavy, Panasonic, Samsung and Toshiba.*

For the following brands, please contact your air conditioning installer or Milieu Labs.

ActronAir, Alcair, Apac, Brivis, Braemar, Carrier, Email, Gree, Haier, HiSense, Lennox, Pioneer, Rinnai, Temperzone, Uniare, Universal, and York.


* Systems over 20 years old belonging to these brands may not require a brand Adapter Kit.


  • For ducted gas heaters

Gas heaters will use 24VAC or communicating control systems. Check with your installer or contact Milieu labs for more information about your system.


  • For thermostats

To find out what system your thermostat uses, you will need to remove the cover. 

Before doing so, turn off the power to your air conditioner. Always refer to the installation manual and safety instructions that came with the controller.

Check the number of wires you have. If you only have 2 wires, you most likely have a communicating system. If you have 3-4 wires, you could have either a communicating or a 24VAC system.  If you have 5 wires or more, you most likely have a 24VAC control system.


If the wire terminals have the letters like Y1, G, R, C, W1, O/B you have a 24VAC control system.

You may see other letters like Y, Y2, W, W2, B, O, RH, RC, indicating you have a 24VAC control system.