VRF Technology

Variable Refrigerant Flow, or VRF technology, is equipment that routes 2 and 3-pipe refrigerant circuits from one outdoor unit to multiple indoor units (or zones) and is capable of providing heating and cooling at the same time as different zones require.

Unlike traditional refrigerant systems that are either “on” and operating at 100% capacity or “off”, VRF equipment utilizes inverter compressors which provide variable speed operation. Why is this so important? Because your HVAC systems seldom need to provide 100% of the capacity they are designed for.

VRF systems routinely operate at partial loads in the range of 30 to 70% which provides more consistent indoor temperatures and humidity levels as well as provides energy efficiency.

Because of this part-load capability, VRF systems are as efficient, and often more efficient, than commercial chiller/boiler systems while at the same time offering much greater design flexibility and much more usable square footage. .

• Very efficient –similar or better than chillers, 180% as efficient as standard splits and RTU’s
• Small space requirements = more net rentable SF.
• Individual room control – indoor fan coils range from ½-ton up to 8-ton and can heat and cool independently.
• Power distribution – allows building owners to proportion electrical consumption between tenants and bill via automated electronic means.
• Remote control and monitoring via internet.
• Durability – VRF gained a lot of ground in Japan and the Caribbean 25 years ago because they were designed for use where saltwater air corrosion and hurricanes are common.
• Durability – these systems have been outlasting chiller plants.
• Excellent dehumidification – which is great for building preservation.
• Design flexibility – wall mounted, ceiling mounted, concealed non-ducted cassettes fit within acoustical ceiling tiles, and concealed ducted indoor unit types up to 8-ton units.
• Very low maintenance (particularly compared to central plants).
• Modular installation: these systems are great for retrofits, “add-on” tonnage, and phased construction.
• No gas required; all electric.  No auxiliary heat strips needed.
• Suitable for a broad geographical range.  These systems perform to subzero temperatures.

• The most pronounced disadvantage to VRF technology is that the manufacturer’s do no limit unqualified mechanical contractors from purchasing these systems.  To get the efficiency, durability, and superior control these systems provide, the piping systems and control systems must be installed per the manufacturers’ very specific instructions.
  Purchasers of VRF installations should qualify their installers by requiring all of the following:
  • Field Supervisors shall have attended the manufacturer’s classes totaling 4 days.  Each manufacturer varies, but generally supervisors shall have completed the “2-day Installation” class and an additional 2-day class titled “Commissioning” or “Service” depending on the manufacturer.  Plus references for three previous installations.
  • All field personnel handling any part of the refrigerant piping system, control wiring, or actual equipment shall have completed at least the “2-day Installation” class offered by the manufacturer prior to commencement.
  • All mechanical contractors submitting proposals for the work shall substantiate their VRF experience detailing the scope, type of system (heat pump or heat recovery), tonnage, and provide references for the work.
  • All piping shall be brazed only when flowing nitrogen and flared with manufacturer recommended tools.  All piping shall be pressure tested to manufacturer guidelines.  All refrigerant piping systems shall be vacuumed to below 500 microns and observed by owner’s appointed representative prior to adding of “trim” refrigerant and commissioning (start-up).
  Start-up and commissioning shall be performed only by a manufacturer certified commissioning agent which may be a qualified contractor, manufacturer’s representative, or manufacturer’s employee.  VRF manufacturers limit and void their warranties on systems not properly installed and commissioned.