Imagine heating or cooling each room in a building to the occupants’ preference using a bare minimum of energy.
Variable refrigerant flow (VRF), also known as variable refrigerant volume (VRV) is an HVAC technology which uses refrigerant as the cooling and heating medium. As with minisplit units, the refrigerant in a VRF system is conditioned by a single outdoor condensing unit and circulated within the building to multiple indoor units without the benefit of ductwork.
VRF systems use variable motor speed and variable refrigerant flow to heat and cool, unlike standard units which use a simple on/off operation. They feature inverter compressors which operate with lower power consumption and partial heating or cooling loads; multiple indoor units on the same refrigerant loop; and a modular design offering the ability to grow the system.
VRF systems also allow users to control heating and cooling individually in each room (or zone), and with some units, operate heating and cooling at the same time. The benefit of variable motor speeds is that VRF technology uses far less energy to heat and cool, often saving up to 55% in utility costs. This savings offers a quick return on investment and state-of-the-art heating and cooling.
How does a VRF system work?
When turned on, the fully automatic VRF HVAC system notes the desired room temperature set by the occupant (or central controller) and notes the outdoor ambient temperature. It then implements its logic and operates the compressor at the exact level needed to reach the desired indoor comfort level.
When another indoor unit is turned on, the outdoor unit recalculates the requirements from all of the indoor units and increases the compressor load, according to demands. The ability for a VRF HVAC system to adjust to the outdoor conditions is its ”secret sauce” and what makes it so energy efficient, compared with traditional water cooled systems with chillers and fan coils.
A VRF System eliminates air temperature fluctuations
The key to comfort is to avoid swings in room temperature. In traditional systems, compressors are either on or off, so fluctuations in room temperature occur as the compressor stops and starts again.
In a VRF system, since the speed of the compressor can be varied, it can operate continuously for longer periods. Innovative compressor technology modulates the flow of refrigerant according to the exact demands of pre-sets in individual areas of a building. This allows the system to deliver heating or cooling as required to each room without fluctuation.
As there are no ducts in a VRF system, no temperature loss occurs as it does with traditional systems when treated air moves through ductwork. The result is consistent heating and cooling at very high energy efficiencies.
As an added benefit, VRF systems greatly reduce ambient noise, as they run much quieter than traditional HVAC systems.
Types of VRF HVAC systems
VRF HVAC systems appear as cooling-only systems, heat pump systems and heat recovery systems, which can heat and cool at the same time.
A typical system consists of at least one outdoor unit, several indoor units, refrigerant piping and communication wiring. Each indoor unit is controlled by its own wired panel and some systems offer wireless remote control and centralized controllers to enable controlling all indoor units from one location.
The outdoor units are lightweight and take up little space. This allows the opportunity to install the outdoor unit in a service elevator or on a rooftop without the need for installing additional support structure for the roof.