VRV or VRF? Two Names, One Advanced HVAC Technology

What's the Difference Between VRV and VRF?

Many people mistakenly believe that VRV and VRF are two distinct HVAC technologies. In fact, VRV and VRF are different terms that refer to the same HVAC technology. The first VRV HVAC systems, which relied on inverter-based compressors, were invented by Daikin in the early 1980s.

Daikin then registered the VRV term, which stands for Variable Refrigerant Volume, as an official trademark. When other HVAC companies created their own VRV system iterations, they adopted the name VRF, or Variable Refrigerant Flow. Herein lies the root of the VRV vs VRF ambiguity. Eventually, VRF became the more common term for these types of systems. This is the term we will use for the rest of this article.

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What is a VRF HVAC System?

While traditional split HVAC systems employ a single external condenser, VRF air conditioning systems feature several, allowing them to dynamically modify the amount of refrigerant flowing to each indoor unit in response to the distinct demands of connected zones.

Considered the "Rolls-Royce" of HVAC technologies, VRF systems are based on several principles:

Refrigerant only - refrigerant is the only coolant used in the system (as opposed to chilled water systems, where refrigerant is used for cooling/heating and water is circulated throughout)
Inverter compressors that allow lowering power consumption with partial cooling/heating loads
Several air handlers (indoor units) on the same refrigerant loop/circuit
Modular expansion capability (especially applicable for large projects that can grow in stages)

Typical VRF System Configuration

A typical system consists of an outdoor unit (comprising one or multiple compressors) and several indoor units (often mistakenly called "fan coils") that are connected by refrigerant piping with Refnet Joints (copper distributors), and communication lines.

The communication lines connect the outdoor and indoor units as part of a closed-loop network. This is an essential part of any VRF setup.

As for control, each indoor unit is controlled by its own wired control panel, while it is also possible to use wireless remotes (IR) and centralized controllers, which allow controlling all indoor units from one location.

How Does a VRF HVAC System Work?

The operation logic of VRF air conditioning systems is internally integrated and based on the proprietary technology of each VRF manufacturer.

In general, the system receives inputs from the user (e.g., desired temperatures) and the surroundings (outside ambient temperatures). Based on this data, it implements its logic in order to get to the desired conditions, while optimizing power consumption.

The ability to make adjustments in response to outdoor conditions is one of the main factors that make VRF systems so efficient compared to traditional water-cooled systems, which are based on chillers and fan coils.

To better understand how VRF works, let's look at a typical application scenario with one outdoor and multiple indoor units.

A Typical Application Scenario

As a starting point, the system is in a standstill condition (everything is turned off). Once a user turns one of the indoor units "ON" using its local remote, the outdoor unit is notified and starts working. To begin with, it will evaluate the outdoor conditions (temperature) and the operating indoor requirements (operation mode, set point temperature), then start running the compressor at the exact level required to comply with the requirements.

When another indoor unit is turned on, the outdoor unit recalculates the requirements of all indoor units and then increases the compressor's output to meet demand. This is, in fact, a continuous process that starts whenever a variable pertaining to the VRF system’s operation changes. As described, this system is fully automatic and regulates its power consumption based on the demand generated by indoor units in conjunction with the ambient temperature outside.

Users influence the desired indoor comfort conditions by modifying the operation mode (on/off), operation state (cool/heat/fan/dry/auto), setpoint temperature, and fan speed (high/medium/low/auto). Controlling those parameters is the only thing required to properly operate a VRF system.

VRF HVAC System Types

Cooling-Only Systems (Less Common) – As the name suggests, cooling-only systems are not capable of heating. However, “fan” and “dry” modes are available and can be activated independently by each indoor unit.

Heat Pump Systems (Common) – Heat pump-based HVAC VRF systems allow all indoor units to both heat or cool, but the system cannot handle both activities at the same time. However, “fan” and “dry” modes can be set independently by each indoor unit.

Heat Recovery Systems (Less Common) – The most sophisticated sub-variation of VRF setups, heat recovery systems enable both cooling and heating by each indoor unit, independently and simultaneously.

What Are the Key Advantages of a VRF HVAC System?

Having discussed VRF system technology, subtypes, and a typical application scenario, one question remains: What benefits do VRF systems offer over more traditional HVAC setups? Following are a few key features.

Energy Efficiency VRF systems are designed to adjust refrigerant flow according to each zone's heating or cooling needs, consuming the minimum energy required to maintain desired conditions. Another benefit is their ductless operation, which prevents energy waste caused by leaky or unprotected ductwork.
Scalability With the ability to connect multiple indoor units to a single outdoor unit, VRF systems can easily be tailored to meet the specific needs of any space\building. This modular design allows for phased installations, which means VRF HVAC systems can be expanded over time without requiring extensive modifications.
Easy Installation Ducted HVAC systems are notoriously bulky and heavy. VRF systems are typically significantly more compact, not requiring ducts, distribution fans, water pumps, and pipes. As a result, installation is usually easier and less physically taxing, while less space is needed for units and equipment.
Simultaneous Heating and Cooling VRF heat recovery systems make it possible to simultaneously heat and cool different zones on a single refrigerant piping system, an impossibility in traditional HVAC systems.
Reliability VRF system components operate only when required and can do so at partial-load conditions, reducing wear and resulting in fewer malfunctions.
Quiet Operation Noise pollution can be a significant concern with traditional HVAC systems. VRF systems typically operate at lower noise levels, with indoor units minimizing ambient sound through the use of inverters and the elimination of ductwork.

Smart VRF System Integration & Management

Whether using a VRF or a Daikin VRV, HVAC systems can be further optimized by adopting advanced automation and management platforms.

Home automation systems are often preferred in the residential market, while building management systems (BMSs) are more commonly used in commercial facilities. However, integrating VRF/VRV systems with BMSs and home automation platforms can be complex and expensive.

Introducing CoolMaster, a universal, plug-and-play VRF/VRV gateway that natively supports all major HVAC, BMS, and smart home brands: facilitating a simple, reliable integration.

While integrating VRF/VRV HVAC systems with BMS and home automation platforms provides improved control capabilities, these systems cannot usually access more complex service data.

Would you like to proactively and intelligently diagnose and service your VRF HVAC? Check out CoolAutomation's solutions for HVAC service providers and professionals:

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VRV or VRF?