Everything You Ever Wanted to Know About HVAC Controls

HVAC or heating, ventilation, and cooling system are one of the significant temperature and humidity controlling setups that residential and commercial establishments have. In residential areas, you have a thermostat, one of the most accessible HVAC controls. After all, you need to change the temperature setting, and the rest of the work will be automatically done.

Now, while people get excited over using the HVAC system, they must acquire fundamental knowledge concerning controlling infrastructure and equipment behavior. Keeping this in mind, we have explained the types of HVAC control systems, their working, and several aspects.

What is an HVAC control system?

Although we have explained above that you can use the thermostat to adjust the temperature and instruct the HVAC system toil what temperature it should work. However, it only applies to residential places since the circuit is simple. But the control structure changes if we consider the commercial establishments where the HVAC system is complicated.

Every commercial or complex building has a Building Automation Management system that controls the sensors, alarms, energy flows, and even the HVAC system. The main reason for bringing all these operative units under one roof is to promote the concept of a smart and innovative building management system.

Parts of HVAC controllers in a BAS

The HVAC controls included in BAS can be divided into four parts, each controlling a specific section of the system. For your in-depth understanding, we have explained everything below.

Software system

As previously discussed, the HVAC system in buildings and commercial establishments is highly complex. Plus, there are multiple levels to which the HVAC system is connected. That's why you need a centralized control tower, also known as energy management software.

You can pass several commands through it, and the HVAC system will accordingly function, whether it is lowering the air temperature or allowing the cold air to pass into the selected rooms.


The modern-day networking infrastructure in most HVAC controls comprises two major parts. First, the CAT-5/6 Ethernet cables take the data from the energy management software to the controllers.

On the other hand, the RS-485 twisted pair cables are responsible for maintaining channel communication between the peripheral or field devices and the controllers.


The controllers act as the intermediary. These are primarily used to control the end devices and ensure the message is properly relayed from the central software based on user actions. Certain separators in the controller circuits allow specific end devices to function only.

For example, if the HVAC system is connected to five rooms in a building and you instruct to turn the AC on in two rooms only, the controllers will bifurcate the message. It then sends the message only to the end devices in the two rooms being asked. This way, the AC in the other three rooms remains off.

End devices

The last part of the HVAC controls is the end device. It can be the thermostat, the air conditioner, the HVAC ducts, or any other decide connected to the HVAC networking infrastructure.


This article explains what the HVAC controls are and the four major parts to be found in any complex circuit. These parts will vary in detailed construction and functions based on the building requirements. That’s why we have given a brief overview to help others understand more about the HVAC control system.