While many believe that VRF and VRV are different, these are simply two terms for the same technology. Using compressors based on inverter technology, the first VRV systems were invented during the 1980s.
As a leader in the commercial HVAC services industry, Daikin trademarked the VRV (variable refrigerant volume) term. All other companies using similar technology refer to it as VRF (variable refrigerant flow). VRF has become the most common term used to describe these systems, and that’s what we’ll use in this guide.
VRF HVAC: What Is It?
VRF is one of the most advanced HVAC technologies on the market today. It’s a sophisticated system based on principles such as:
- Refrigerant only. In a VRF system, refrigerant is the sole coolant used. In contrast, chilled water systems use refrigerants to cool or heat the water before it’s circulated.
- Inverter compressors. These components allow for a decrease in power usage when heating and cooling loads are low.
- Multiple air handlers. VRF systems use more than one air handler on a single refrigerant loop.
- Room for expansion. A VRF system is great for projects with plans for future additions, as it can be expanded in a modular fashion.
In the sections below, we’ll explain the structure and function of VRF systems.
VRF System Structure
Variable refrigerant flow systems consist of an outside unit with one or more compressors, multiple indoor units (sometimes referred to as fan coils), refrigerant tubing that runs from the outside to the inside of a building, and the wiring through which electrical signals are sent.
The communication wiring in a VRF system is comprised of a two-wired cable that runs from the outside in, creating a closed loop. This is a crucial part of a VRF system installation. As far as controls go, each indoor unit is controlled by a panel. In some systems, centralized controllers and IR remotes are used to operate all indoor units from a single location.
How VRF HVAC Systems Work
The operational logic of a VRF is built into the system and is unique to each manufacturer. No matter who made it, a VRF system gets a user’s input—such as the desired temperature—as well as temperature readings from outside. According to the data it receives, the system uses its logic to achieve the user’s preferred condition and optimize power consumption.
These systems’ ability to adjust to changing outdoor conditions is one of the biggest factors that makes them so efficient compared to conventional water-cooled HVAC systems that use fan coils and chillers. Below, our commercial HVAC repair experts will explain the function of a typical VRF system in detail.
- In the beginning, the system is deactivated, and everything is switched off.
- Once the user turns an indoor air handler on by IR or local remote, the outdoor unit receives a signal and turns on. Then, the unit examines outdoor conditions and indoor requirements, using that information to operate the compressor at a level that meets those requirements.
- When a second indoor unit is switched on, the outdoor component recalculates the indoor requirements and increases compressor output to meet the new demand level.
The process continually repeats itself when changes occur. As mentioned, VRF systems are fully automated, and they regulate their power consumption based on outside conditions and the information received from the indoor air handlers.
User input has a direct effect on indoor comfort levels. VRF system users can modify the operational mode (on or off), operational state (cool, heat, dry, fan, or auto), the setpoint temperature, and the fan speed. Controlling such parameters is crucial to the system’s proper operation.
Types of VRF HVAC Systems
There are several options, and the user’s choice will depend on the size of the building, their comfort needs, and their budget. The most common types of VRF systems include:
- Cooling only. As implied by the name, these systems only cool; no heat is available. Dry and fan modes are used for each indoor air handler.
- Heat pumps. All indoor units can cool or heat (but not simultaneously). Fan and dry modes are used for all indoor units.
- Heat recovery systems. These are the most complex VRF systems. Here, each indoor unit works independently, meaning that heating and cooling functions can be used at the same time.
Whether you’re cooling a large warehouse or a small office building, a VRF HVAC system offers the versatility and efficiency you need. The team at Inverter Mechanical Piping Solutions has more than 35 years of mechanical contracting experience in the installation, maintenance, and repair of HVAC systems. Let us put our knowledge to work for you—call or click today to schedule an evaluation.