Searching for HVAC integration solutions makes you probably wonder about the HVAC system as a whole. Not just where to connect the wires. After all, when you are trying to connect a Control4 Thermostat to VRF systems such as Daikin, Mitsubishi, LG, Samsung, Fujitsu, Gree VRF, you might feel confused.

Typical Control4 Thermostat Connectivity

Let’s look at a typical HVAC control case. You have the Control4 thermostat that you would naturally connect as follows:

Control4 Central Controller and HVAC

Five Wire Thermostats

A thermostat is an inherent part of the Unitary HVAC system, which needs a control=brain=logical part, to make the system reach and keep a set point temperature.

The traditional thermostat is the decision maker of the system, the brain, which engages with the Air Conditioning system using the well-known 5-wire:

  • Cool (Y)
  • Heat (W)
  • Fan (G)
  • The other 2 wires are meant to power the thermostat itself
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If you wish to dive a tiny bit deeper: a thermostat dictates an on/off command to the relay it is connected to on the HVAC. Let's say you need to cool down a hot San Diego apartment to a comfortable 72°F. You turn on your AC in “Cool” mode and fix your set point to 72°.

The HVAC system keeps cooling until a thermostat senses 72°F (or a bit below). Once the room temperature reading is 72, the thermostat switches the HVAC unit’s cooling relay OFF, using the Cool (Y) wire.

A thermostat is the brain of the system, operating on a principle of: "I shut you off once you finish doing your job!". Pretty simple, right? And that's how we like it:

Control4 Central Controller and HVAC - On and Off

Two or Three Wire Thermostats

However, once you try to connect that Control4 thermostat to a VRF system by Daikin, Mitsubishi, or LG (and others for that matter), the problems begin. This is the point at which you start wondering what to do about the missing wires of the HVAC indoor unit.

You see, we are all used to seeing that control panel as a thermostat, the brain of the system. However, the 2 or 3-wire thermostat is in fact not a thermostat at all. It is a Wired Remote Controller (WRC) that communicates with the VRF indoor unit, using a communication protocol.

The WRC that comes along with a VRF is essentially a control panel. It delivers users’ climate requirements ("Cool to 72°F") to the VRF indoor unit. That unit then translates the request into an engineering demand, and sets the unit to operate and deliver the desired climate conditions. Think of this process much like the Control4 central controller, managing all the devices you have installed. Your Home Automation system components and devices are communicating with each other using a network.

The HVAC manufacturers apply proprietary networks and closed communication for external access, using brand specific protocols. So, if you have a Daikin VRF or an LG, those two systems run the data on entirely different networks, using completely different protocols.

How to make the VRF HVAC work with Control4 Thermostat?

So, the question remains, how to make a Control4 Thermostat to work with a highly sophisticated Daikin VRV? The answer is simple. You don’t.  

It’s like trying to make a digital I/O work with a communication bus. However, hold on before you close the browser and secretly curse the star we were born under - we have a better solution.

Connect the Control4 Central Controller to the VRF HVAC Using CoolmasterNet

It's a good idea for two reasons:
  1. You get a bi-directional communication between the Control4 system and the VRF HVAC, with zero latency. You have achieved your initial goal of controlling the HVAC!
  2. You can still have Control4 Thermostat on the wall and keep your customers’ habits of controlling the HVAC with a wall mounted control panel
How? Just add a CoolAutomation gateway, that allows the commands to get from the controller to the HVAC (and a response back). Like this:

Control4 Central Controller and CoolMasterNer

Now connect Control4 thermostat to the system like this:

Control4 Central Controller, Thermoastat and CoolMasterNer

Connecting Control4 thermostat this way is most beneficial to your user. We are all creatures of habits, and many of your customers still expect a wall mounted control device. In this case, the device is connected to the central controller, and not directly to the HVAC. So, your thermostat is operating through two intermediate devices that allow translating and connecting two distinct systems.

In Conclusion

If you are trying to control an advanced HVAC system, particularly those with high growth market penetration such as Daikin VRV or other VRF brands, using 5- wire thermostat, remember this:
  • A 5-wire thermostat will not work with a non-conventional HVAC, such as Daikin, Mitsubishi, LG, and other VRF systems
  • Instead, use a CoolMasterNet gateway that connects the Control4 central controller, directly to the HVAC system
  • Use a Control4 thermostat, connecting it to the central controller, not to the HVAC
Are you interested in more information? Contact us

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