Windy City Reps

How Does a Variable Refrigerant Flow System Work?

March 18, 2022

If you work with commercial HVAC systems frequently, chances are you’ve heard of variable refrigerant flow, or VRF, systems. However, you might not know just how this technology works—or the benefits it offers in commercial and institutional settings. 

​In a nutshell, a VRF system is a ductless HVAC system which uses either a heat pump or heat recovery system to simultaneously heat and cool multiple zones. Its versatility, efficiency, and effectiveness make it a valuable option for building managers who are considering new HVAC systems. However, it’s worth having a basic understanding of just how VRF systems operate and what makes them stand out. 

​Basics of VRF Systems

​Like other ductless (or mini-split) HVAC systems, a standard VRF system consists of an outdoor unit connected to one or more indoor units. However, in VRF systems, the outdoor unit is connected to its counterparts via refrigerant piping and uses R410-A refrigerant to heat and cool indoor spaces. Because the system can control the flow of this fluid through various evaporator coils, it can heat and cool multiple zones—hence the name “variable refrigerant flow”. This is paired with variable-speed compressors and both indoor and outdoor fans, which contribute to the system’s efficiency and comfort.

​There are two basic types of VRF systems you’re likely to encounter, categorized by how the system cools compressors. Compressors support variable motor speed, which is responsible for the system’s control over refrigerant flow. 

Compressors are responsible for transferring refrigerant to zones, so making sure they don’t overheat is essential. To address this, VRF systems use either an air- or water-cooled mechanism. Air-cooled compressors are connected via a loop of refrigerant, while water-cooled compressors are connected to a water loop. 

Both systems have their own advantages and drawbacks. Air-cooled systems usually carry a lower upfront price tag, as they require no additional parts. However, because they require access to outside air, they can present designers with some difficulties in placement and installation. Water-cooled systems, on the other hand, are more compact and offer more installation flexibility. However, they also tend to cost more than air-cooled systems, as they require additional equipment to maintain the water-loop temperature.   

Generally, the system you choose will come down to what your distributor recommends. Both air- and water-cooled VRF systems offer many features and benefits, and every building has its own requirements. Manufacturers like Samsung offer a variety of both air- and water-cooled VRF systems depending on the ambient environment and your cooling and heating needs.

​Benefits of a Variable Refrigerant Flow System

​So, why would you choose a variable refrigerant flow system over your other options? Simply put, they’re efficient, quiet, compact, and versatile. 

Efficiency and operating costs are where VRF systems really shine. Because they don’t have to heat or cool entire buildings and don’t need to push water or air around the building to run, they use less energy and can cost up to 34% less to run than conventional forced-air systems. 

​This also keeps noise down, as the only sound you’re likely to hear from a VRF system when it’s operating is the fan coil units. In settings like hotels, schools, and offices, this is a major advantage.  

Often, space is a major concern when it comes to HVAC systems. Because they don’t require ducting and their air handlers are relatively small, VRF systems are generally more compact. 

Finally, VRF systems’ ability to heat and cool spaces simultaneously helps occupants keep comfortable while keeping costs down. In fact, since the refrigerant can be modulated to a significant degree, it is easier to keep the system operating at peak efficiency and effectiveness.

​Design Considerations

​There are three issues to keep in mind when considering a variable refrigerant flow system in a commercial space, either as part of a retrofit or in use during new construction. As with any newer technology, VRF units have a higher price tag upfront; although they are less expensive to run, these savings take some time to add up.

Another key factor is the use of refrigerant pipes throughout the system. They may only be able to extend several hundred feet, compared to ducts that can travel several stories. More importantly, there are considerations in case of any potential leakage. Technicians who work with these systems must be EPA-certified to deal with the hazardous material. While it is not toxic, it can displace oxygen and lead to suffocation.

The final consideration is that since the system does not force air through ducts, specifying engineers must be mindful of ventilation requirements. It is important to maintain enough space for outside air ducts and air handlers when considering them for a new project.

​Find the Right Variable Refrigerant Flow System for Your Project

Windy City Representatives works with leading manufacturers of variable refrigerant flow HVAC systems. To learn more about how we can help you find the right equipment for you, call us today at 630-590-6933.

At Windy City Representatives, we partner with premier HVAC equipment providers to help you design the best HVAC system for your building or facility’s needs and budget. 

Contact us today for a quote or bid.
200 Windsor Drive
Oak Brook, IL 60523
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