A Guide to Variable Refrigerant Flow HVAC Systems

A Guide to Variable Refrigerant Flow HVAC Systems

Retail spaces, hotels, offices and multifamily buildings often see significant energy waste and high utility costs as they try to accommodate the climate control needs of multiple spaces with a one-size-fits-all HVAC system. Variable refrigerant flow HVAC systems offer a customized approach to HVAC that helps facility managers and building owners reach their energy efficiency and utility savings goals.

VRF systems operate and adjust based on the specific needs of each room within a building, providing an HVAC system that feels just right. GE Appliances, a Haier company, Air & Water Solutions, provides VRF systems that deliver custom comfort and energy efficiency with the added benefits of flexible installation and ease of service.

This guide provides a comprehensive understanding of VRF systems, their benefits, the problems they solve and how they stack up against other HVAC solutions.

What are variable refrigerant flow systems?

HVAC systems have always been used to conveniently create more comfortable indoor environments, and VRF system development was driven by the need to increase energy efficiency.

 VRF systems maintain precise temperature control by using inverter-driven compressors that adjust speed based on cooling or heating demand from hotel guests, office tenants and people in multifamily residential buildings. Different areas may have inconsistent heating and cooling needs due to distinctions in use and occupancy. VRF systems adapt to these dissimilarities by facilitating individual temperature settings for each zone. With VRF systems, each indoor unit comes with a remote control or thermostat, allowing users to select their preferred temperature. As the demand for convenience rises, innovations such as VRF systems that adapt to needs in real time have been monumental.  

VRF systems have four key components:

  1. Outdoor Unit: Houses the compressor and the heat exchanger

  2. Indoor Units: Can be wall-mounted, ceiling cassettes or ducted

  3. Refrigerant Piping: Connects the outdoor and indoor units, allowing for the transfer of refrigerant

  4. Control Systems: Sophisticated control systems manage the operation of the units, ensuring optimal performance and comfort

GE Appliances VRF systems are equipped with advanced features that provide even more performance benefits. The pulse-modulating valves inside each indoor unit allow for precise control of refrigerant flow. As the temperature changes, the valve adjusts the refrigerant flow to maintain the desired comfort level. This ensures optimal performance and consistent temperature.

 

How do VRF systems work?

VRF systems use advanced technology and algorithms to control the distribution of refrigerant. These systems are capable of adjusting instantly to varying indoor conditions, maintaining optimal comfort levels while minimizing energy consumption. Here’s how it works:

  • By continually monitoring and adjusting the operation of the compressor and expansion valves, VRF systems ensure each area receives the precise amount of refrigerant needed for load conditions.

  • VRF systems provide heating and cooling simultaneously to different areas using heat-recovery technology that redistributes excess heat from areas requiring cooling to zones needing heating, significantly improving efficiency and comfort.

VRF vs. Central AC

The biggest difference between the two is that VRF systems are highly scalable, giving facility owners the flexibility to add units, while central air-conditioning systems aren’t.

Traditional central AC systems use a single fan coil unit that cools the air around it and then distributes it through the HVAC duct system.

Central AC Systems Are:

  • Inefficient during low demand: Central AC systems operate on a fixed, on-and-off basis. The fixed operating system of central AC systems may lead to energy waste and inconsistent cooling.

  • Hard to scale: These systems maintain temperature throughout larger spaces. Increasing the capacity of a central AC system requires making significant changes to the ductwork and the design of the system, which can be costly and time-consuming.

  • Space consuming: Central AC systems also require more room for installation than VRF systems.

The word variable is the key to understanding VRF systems. They use multiple fan coils and variable refrigerant flow technology to adjust depending on the specific heating and cooling needs of different zones.

VRF Systems Are:

  • Highly scalable: They are engineered to serve multiple zones or rooms and allow for the easy addition of indoor units without the hassle of reconstructing the system.

  • Energy efficient: They supply refrigerant only when needed and run less frequently.

  • Flexible in design: Various indoor unit options can accommodate different architectural needs, including installation in tight places.

  • Cost efficient over the long term: While VRF systems can cost more to install than traditional systems, the energy savings and ease of maintenance can offset the cost difference over time.

VRF vs. Mini-Split Systems

Mini-split and VRF systems have significantly different capacities. Mini-split systems consist of one outdoor unit connected to one or a few indoor units and are commonly used for individual rooms or smaller spaces. VRF systems are designed for larger installations including, multifamily and commercial buildings.

Mini-split Systems Have:

  • Limited capacity: Mini-split systems are best suited for single zones or smaller buildings.

  • Cost-effective installation: These systems are simple and do not typically require large upfront installation costs.

  • Fixed operation: Mini-split systems may operate at a fixed capacity and can be ineffective at managing varying heating and cooling loads.

VRF Systems Have:

  • Enhanced capacity: Their complex design means they can adjust to different indoor units based on the needs of larger buildings.

  • Advanced design: They offer advanced zoning capabilities, allowing different rooms to be controlled independently.

  • Long-term cost savings: While VRF systems may have a higher initial cost, the energy savings can lead them to be more cost effective in the long run.

What are the different types of VRF systems?

There are multiple types of VRF systems. Which type is best for you and your customers depends on building size, location, needs and the architecture of the building. VRF systems are typically heat-recovery systems and can function in a two-pipe or three-pipe system and be either air-cooled or water-cooled.

Heat Pump vs. Heat-Recovery Systems

Heat pumps and heat-recovery systems both transfer heat, but the way they operate and the applications they are made for are different. GE Appliances Air & Water Solutions VRF systems are dual heat pump/heat-recovery modules.

 

Heat Pump Systems:

  • Transfer heat: Heat pumps extract heat from the air, ground or water and transfer it from one location to another using refrigerants. Heat pump fan coils can provide either heating or cooling based on the outdoor unit mode.

  • Suit large spaces: Heat pumps work well in buildings with large open spaces or a single common area such as gyms, lobbies and open-concept offices with cubicles.

Heat-Recovery Systems:

  • Reuse heat: Heat-recovery systems eliminate heat waste by collecting heat and repurposing it for heating or preheating other areas.

  • Are energy efficient: These systems are energy efficient, capturing and reusing energy that would otherwise go to waste.

  • Work for multi-zones: Heat-recovery systems are best in buildings with multiple zones, including assisted living facilities, schools, offices, dormitories and multifamily buildings.

Two-Pipe vs. Three-Pipe Systems

Two-pipe and three-pipe systems use water to provide heating and cooling in residential and commercial buildings. Both systems use outdoor units, indoor fan coils and controllers. Two-pipe systems use one pipe to supply heating or cooling and one as a return pipe. Three-pipe systems use one pipe for heating, one for cooling and one as a return pipe.

Two-Pipe Systems are:

  • Simplistic: The simplicity of the two-pipe system is a key advantage. Fewer pipes means easier installation and maintenance. They are great for small to medium offices, condominiums and schools.

  • Single purpose: Generally, two-pipe systems can run either heating or cooling but not both at the same time. These systems need to be switched between heating and cooling based on the season.

  • Less expensive to install: Two-pipe systems require less piping work and space to install, leading to lower installation costs.

Three-Pipe Systems Are:

  • Precise: The three-pipe system also allows for precise temperature control and accommodates varying loads, enhancing energy efficiency.

  • Complicated to install: Three-pipe systems have more components, which can complicate installation. The components can also increase costs due to the use of more materials.

  • Multifunctional: These systems can provide heating and cooling to different zones simultaneously, making them ideal for large commercial buildings, hospitals and high-rise apartments and offices.

Air-Cooled vs. Water-Cooled Systems

The key difference between air- and water-cooled systems is their source of cooling. Air-cooled HVAC systems use air to disperse heat from the refrigerant as well as air-conditioning units or chillers that shift heat. Water-cooled systems use water to transfer heat by using chillers that distribute the water to absorb heat from the refrigerant. After the air is compressed, the refrigerant travels to the condenser, which is chilled by water from a cooling tower.

Air-Cooled Systems Are:

  • Easy to install: Generally, air-cooled systems require less complex piping compared to water-cooled systems, allowing for faster and easier installation.

  • Not for hot climates: These systems don’t run as effectively in hot climates where it’s difficult for air-cooled systems to meet cooling needs.

  • Best for smaller areas: Air-cooled systems work well in single- and multifamily homes, small commercial buildings, small to medium offices and rural areas.

Water-Cooled Systems Are:

  • Versatile: They offer consistent performance across a wider range of climates. However, water-cooled systems are not suited for areas with limited access to water.

  • Efficient and effective: Water-cooled systems are more efficient, especially for larger applications and in hot environments. These systems can be more cost effective, as they use less energy over time.

  • High capacity: Water-cooled systems are perfect for larger applications where efficient cooling and steady performance are essential. They are often used in large commercial buildings such as office towers, malls, industrial facilities and recreational facilities.

What are the common applications for VRF systems?

VRF systems are versatile and can meet the needs of a variety of spaces. GE Appliances offers commercial VRF and light commercial VRF systems, each specifically designed for different space sizes.

  • Commercial systems are recommended for heating or cooling single dwellings and multistory buildings. These systems include ducted systems, multi-split systems, ceiling cassettes, VRF systems and chillers.

  • Light commercial systems are designed for small- to medium-size commercial spaces such as shops and offices. These systems provide heating, ventilation and air-conditioning.

Simplified installation is beneficial for small spaces and historic buildings.

GE Appliances VRF systems are designed with built-in handles and skids for easy handling and rigging during installation. They can also be integrated easily with building management systems and extended piping limits. The versatile piping connection design allows you to route the pipe according to specific needs. The lack of ductwork in VRF systems makes them easier to install, especially in tighter spaces and historic buildings where adding ductwork would be too costly or difficult.

Lower energy consumption can help achieve sustainability program certifications.

VRF systems are highly energy efficient and only use the energy needed to meet the current load. In a traditional system, the space is conditioned regardless of occupancy, which leads to considerable energy waste. GE Appliances VRF systems use a part-load operation to run below full capacity, increasing energy savings while decreasing wear and tear and utility costs.

The efficiency and flexibility of VRF systems can help builders meet sustainability goals and contribute points toward green building certifications such as Leadership in Energy and Environmental Design.

Quiet operation is ideal for hotels, multifamily buildings and dorms.

Traditional systems can be noisy and disruptive, but VRF systems operate at low decibel levels, creating a comfortable and quiet environment. VRF systems use variable-speed compressors that adjust their speed based on the cooling or heating demand, which eliminates the noise of the system alternating on and off. These systems are created with sound-absorbing materials and low-noise fans that also decrease noise levels.

Compact design enhances building aesthetics.

VRF systems use smaller refrigerant pipes, which can be integrated more discreetly into the building’s design. This gives architects more freedom in designing buildings without the need to accommodate bulky ductwork, preserving the building’s aesthetic appeal. VRF systems are available in multiple design options, including ceiling cassettes, wall-mounted units and floor-standing units, which allows for a tailored approach to heating and cooling based on the specific requirements of the building and the preferences of the customer or architect.

Reasons To Choose GE Appliances VRF Systems

GE Appliances offers a variety of VRF system options ranging in weight and size but consistent in quality. They provide precise and superior comfort, delivering temperature control within 1°F of their set point and allowing users to enjoy comfortable heating in conditions as cold as –22°F and cooling in temperatures as high as 122°F.

 

Efficiency Features of GE Appliances VRF Systems Include:

  • Enhanced vapor injection compressor

  • Speedless inverter DC motor

  • A sturdy one-piece, four-sided heat exchanger

GE Appliances VRF systems offer simplified installation with the MRV-Link communication network, which is engineered to replace the labor-intensive conventional wired daisy chain network and eliminate the need for communication wires between indoor units.

The external static pressure design offers unparalleled flexibility, allowing for the installation of outdoor units in the desired location, even indoors in some applications. The versatile piping connection design and flexible piping limits allow the installer to route pipe according to individual building needs.

For easy maintenance, GE Appliances MRV-5 outdoor units feature a swing-out electronic control box design that conserves interior volume within the unit. All GE Appliances VRF systems are tested to the latest U.S. Department of Energy and Air-Conditioning, Heating, and Refrigeration Institute standards and regulations and feature intelligent controls to prevent scroll gas leakage, reducing the scroll clearance volume.

Remote Service Monitoring

GE Appliances VRF systems allow control of the temperature and air-conditioning system in a building even when you are not there. A smartphone app provides a convenient way to control the system and receive maintenance notifications.

Become a GE Appliances partner.

Join the team for comprehensive training, service and marketing support. Learn more at the GE Appliances VRF resource portal.

Frequently Asked Questions About VRF Systems

How do VRF systems integrate with existing HVAC systems?

VRF systems can be combined with traditional systems to create a hybrid solution, allowing buildings to leverage the benefits of both systems to optimize energy use for heating and cooling. Advanced controls can manage the operation of both systems, ensuring that they work together efficiently.

VRF systems also can be retrofitted into buildings with existing ductwork or other HVAC infrastructure. This can be more cost effective than completely replacing an old system. VRF systems can also be connected to a building management system, allowing for centralized control and monitoring of HVAC operations.

What is the expected life span of a VRF system?

The expected life span of a VRF system ranges from 15 to 20 years, although this can vary based on several factors. Proper installation by professionals, regular maintenance, and routine inspections and cleaning can extend the life span of a VRF system.