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 s.

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 EfficiencyVRF 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.
• ScalabilityWith 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 InstallationDucted 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 CoolingVRF 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.
• ReliabilityVRF 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.

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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.

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All-electric Variable Refrigerant Flow (VRF) technology is the fastest growing segment of the commercial HVAC industry. Across the United States, developers and owners are discovering how VRF heating and cooling systems help future-proof their buildings and reduce operational costs.

VRF technology divides a building into zones customized for comfort and energy efficiency. With no need for fossil fuels, an all-electric VRF system provides heating and cooling by cycling refrigerant between an outdoor unit and each zone’s ductless or ducted indoor unit(s). Up to 50 indoor units can connect to a single outdoor unit.

Zones have individual set points based on usage, occupancy, typical solar loads and user preferences. Facility managers can empower occupants to customize comfort in their zones while retaining the ability to optimize heating and cooling with centralized equipment control. VRF controls can integrate with building automation systems through standard communication protocols like BACnet®. 

A Variable-capacity Heat Pump System for Sustainable Heating and Cooling

Conventional systems emit byproducts including carbon dioxide (CO2), nitrogen dioxide (NO2) and particulate matter 2.5 (PM 2.5) when they generate heat by burning fossil fuels. As building codes and markets demand lower carbon footprints and greater sustainability, VRF systems offer a cleaner and more effective way to heat buildings.

Heat is everywhere. What we experience as heat is the natural movement of thermal energy between objects with different temperatures. Thermal energy moves from warmer objects to cooler objects. Instead of burning fossil fuels to generate heat, VRF systems use refrigerant to capture and repurpose existing heat from the environment. Air-source VRF systems draw heat from outdoor ambient air, while water-source VRF systems draw heat from a nearby water source such as a geothermal well. With our advanced Hyper-Heating INVERTER® (H2i®) technology, VRF systems can provide continuous heating at temperatures as low as -27.4° F.

In heating mode, the VRF outdoor unit expands the refrigerant gas until the gas is colder than the ambient air or water. The temperature difference enables the outdoor unit to extract thermal energy and transfer the heat to indoor units via refrigerant lines. Using this method, VRF technology provides more energy as heat than the system uses as electricity.

During cooling, indoor units absorb and transfer heat from interior zones to the outdoor units for rejection, leaving a cold indoor coil. A fan blows air across this coil into the space. The VRF system’s ability to provide both heating and cooling eliminates the need for separate air conditioners and heating systems.

Indoor units connected to a VRF heat-pump system operate in one mode at a time: heating or cooling. For buildings with diverse comfort needs, such as hotels or apartment buildings, building owners can choose a VRF heat-recovery system for simultaneous heating and cooling.

Quiet and Energy-efficient

VRF systems operate at ultra-quiet sound levels and use minimal energy to maintain each zone’s set point. The outdoor unit’s INVERTER-driven compressor varies fan speeds and the amount of refrigerant delivered to the indoor units, so the capacity and energy use match the real-time conditioning needs of the zones. As conditioning demands fluctuate with occupancy, activities and outdoor temperatures, the VRF system ramps up and down as needed to keep indoor temperatures steady. This method provides more precise comfort control, quieter operation and greater energy efficiency than conventional systems limited by noisy and energy-intensive on/off cycles. The continuous operation of VRF fans also helps distribute air, eliminate hot and cold spots and prevent the need to blow air at high velocities.

Compact and Modular for Cost Savings and Found Revenue

Lighter and more compact than conventional equipment, VRF systems can reduce upfront costs by requiring less structural support and fewer alterations to building facades. This smaller footprint combined with the diverse selection of ductless and ducted indoor units gives architects and engineers design flexibility to meet aesthetic and application requirements. Developers and building owners can also take advantage of the compact, ultra-quiet equipment to create revenue-generating amenities like rooftop lounges and cafes. Additionally, the modularity of VRF technology enables contractors to install systems floor-by-floor so developers can defer portions of the total installation cost until tenants sign leases.

Contact us to discuss your requirements of VRF Air Conditioner. Our experienced sales team can help you identify the options that best suit your needs.