VRF Mini (Variable Refrigerant Flow) HVAC systems are growing in popularity here in Brooklyn & New York City. More businesses & residents are implementing the benefits of VRF HVAC systems. Currently it is the most advanced HVAC technology available. VRF offers the greatest efficiency & targeted temperature control. Gemini Thermo HVAC offers residential & commercial VRF installations.
The distinct advantage of VRF HVAC is indicated by it’s name. These systems are designed for maximum efficiency by varying refrigerant flow. The simultaneous regulation of compressor speed & thus power consumption is what puts VRF on the cutting edge of HVAC technology. There are various types of ductless heat pump systems which generally are all more efficient than traditional HVAC systems. Amongst these VRF systems are the most efficient. In addition to being ductless & zoned, it has the additional advantage of power efficiency through varying refrigerant flow. Some VRF systems called Heat Recovery Systems are also capable of heating & cooling different zones simultaneously, thus achieving even greater efficiency.
The technology was originally introduced in the 80’s in Japan by the Daikin company who marketed their system as Daikin VRV (Variable Refrigerant Volume). The same technology became available from numerous manufacturers as VRF (Variable Refrigerant Flow). VRF became widely popularized throughout Europe & Asia since it’s introduction. It became available in the US in the early 2000’s and really started catching on around 2010.
There are several types of ductless heat pump HVAC systems of which VRF mini is one. In summary there’s the mini split, multi split and VRF systems, which include mini VRF & larger commercial VRF systems. The terms mini split & multi split alone generally refer to ductless heat pump systems without the additional VRF technology. Mini split, multi split & mini vrf all operate on single phase power. The large commercial VRF systems require three phase power.
All of these ductless systems are designed with an outdoor unit (referred to as a heat pump, condenser or condensing unit) which contains one or more compressors. The compressor pumps refrigerant through lines to one or several air handlers (referred to as fan coils, blower coils or heads). The air handlers can be individually controlled at each air handler. Some can also be controlled from a central location. Air is heated or cooled on the spot by the air handler & delivered into the room.
Central air conditioning systems also use refrigerant, outdoor condensing units with a compressor & indoor fan coil air handlers. But with central air systems, chilled water flows through the system, air is conditioned by a central air handler & then forced through ducts to different rooms . The main difference with ductless systems is that refrigerant flows through the whole system & is delivered directly to the targeted location. This eliminates 30-40% energy losses common with ducted systems.
These ductless systems all share the benefit of higher energy efficiency due to being ductless & zone targeted. Though these systems do not require ducts, they can also be integrated into existing duct systems with the same efficiency. In general ductless systems are easier to install, maintain & they save space. Ductless system indoor air handlers are more easily accessible then central air systems which have air handlers in crawl spaces & attics. Another advantage is that if one air handler stops working it will not effect other air handlers.
The simplest type of ductless hvac system is the mini split system. This was the first type of ductless system. It became known as the mini split because the function is split between an indoor & outdoor unit both of which are considerably more compact & streamlined than most standard equipment. Mini split most specifically refers to single zone units with a single air handler. Several choices of air handlers are available which can be mounted on the wall, ceiling or floor. Single zone mini splits are the simplest type of system to install. Often they are used for spot cooling or supplementing central AC by giving greater control over an individual space. Mini splits can also have multiple zones but to be more precise such systems are referred to as multi splits.
Multi split systems are the same as mini splits but they can have 2 to 8 air handlers connected to a single outdoor unit. As with mini split systems they can either cool or heat, but not both simultaneously as some vrf systems can. Multi splits are basically the same as mini vrf systems. They both operate on single phase power. But mini vrf has additional power efficiency technology.
Mini VRF & Large Commercial VRF HVAC
Mini VRF is essentially an enhanced version of the ductless multi split system and achieves even greater power efficiency. VRF is the most energy efficient HVAC system because it is designed to use the minimum amount of power for cooling & heating.
VRF threefold power saving features:
- VRF is ductless. Ducted systems can lose 30-40% of energy through duct leaks as well as duct heat gain. This is heat absorbed by the ducts which are typically located in unconditioned spaces like attics & ceilings. Ductless systems eliminate this loss.
- VRF has targeted zoning. This enables conditioning of only occupied spaces. Central air systems condition the entire building even if half the rooms are unoccupied. This amounts to using twice the amount of energy which is actually needed.
- VRF varies refrigerant flow. This additional benefit achieves even lower power usage by varying compressor speeds & refrigerant flow. This is accomplished by several mechanisms which regulate energy cosumption. A liquid expansion valve in the air handler limits the flow of refrigerant. A DC inverter (or several compressors) regulates compressor speed. The compressor pumps only the exact amount of refrigerant required to each air handler. This design minimizes power consumption using only a fraction of the system capacity according to the demand.
Some VRF systems called heat recovery (HR) systems can save even more in buildings which require simultaneous heating & cooling of different spaces. The system exchanges hot & cold air between spaces that need cooling & those that need heat. Combined, these VRF power saving features can reduce power consumption by 30-65% compared to conventional systems.
Like Multi Splits, Mini VRF systems support up to 8 or 9 indoor air handlers on a single outdoor unit. Of course, more outdoor units can be added for additional indoor units. For example 2 outdoor units can be combined to support 16 indoor units, all on single phase power. Large commercial VRF rooftop systems for high rise buildings require three phase power & can support up to 48 indoor units on a single outdoor unit. Mini VRF is ideal for residences & light commercial buildings without three phase power:
- new construction, old construction
- buildings with limited space
- single family residences
- luxury apartments
- large custom homes
- multi family homes
- assisted living & nursing homes
- small office buildings
- bank branches
- retail stores
- light commercial spaces
The main culprit in most building energy audits is energy loss through air duct leaks & duct heat gain. Ductless systems deliver refrigerant to each targeted area for on the spot conditioned air.
With ducted systems ducts can be closed, but opening & closing ducts in several rooms every day is impractical. Neither does it give very precise temperature control. In offices sometimes one room down the hall with a large window is too hot while another room is too cold. VRF solves the issue of hot & cold spots & creates a more productive environment for work spaces. Each room can be set to the exact desired temperature. Schedules can also be set to raise or reduce temperatures automatically. Energy saving levels can be set for times when rooms aren’t occupied.
Maximum Energy Savings
Variant refrigerant flow maximizes energy savings. For some projects only a VRF system meets all energy specifications for LEED (Leadership in Energy and Environmental Design), EER (Energy Efficiency Ratio), SEER (Seasonal Energy Efficiency Ratio), and HSPF (Heating Season Performance Factor). VRF has largely contributed to many new constructions achieving LEED certification from the US Green Building Council.
Simultaneous Heating & Cooling
Some Systems called (HR) Heat Recovery Systems can simultaneously heat one space while cooling another. Heat extracted from areas needing cooling is transfered to areas needing heat.
Runs on single phase electricity
Mini vrf requires only single phase electricity compared to large commercial vrf rooftop units which require 3 phase. Many buildings have only single phase electricity.
Fewer breakdowns & less downtime
Because the system runs only when needed & at minimum power, the components undergo less wear & tear; And if one air handler malfunctions the other air handlers are unaffected. Also, with central systems the air handlers & ducts are placed in tight areas like crawl spaces & attics. With VRF HVAC both the indoor & outdoor units are installed in very easily accesible locations. Less wear & tear plus easier accessibility amounts to less downtime & lower repair costs.
Each air handler can be controlled separately, usually with a remote control. Some systems are wifi enabled allowing remote control from mobile devices. Some systems allow additional control from a central location. Schedules can be set for each zone to automatically raise & lower temperatures. Systems ideal for apartment & condo buildings also allow for invidual metering of each residence. Operation & maintenance alerts are available on some systems as well.
Space Savings & Design Flexibility
VRF equipment is compact & requires less space. This leaves more room for ceiling heights & living space in new construction. Construction costs can be reduced with VRF. It makes installations possible in old buildings that have no ducts & limited space. Indoor air handlers are sleek & come in a variety of designs which often can be concealed in ceilings, walls & floors. Refrigerant lines are capable of long runs to enable placement of outdoor equipment in ideal locations. There’s no requirement for flues, intakes, pipes & grilles needed on other HVAC systems. VRF offers specifications & design flexibility not available with any other system. When a project requires individual room temperature control & LEED energy specifications of 30% savings, VRF is likely the only option.
Healthier Indoor Air Quality
Another problem with central air systems is that air is filtered at one central location. Leaks in ductwork can still allow dust & contaminants to enter the system & be blown throughout the building. With ductless systems air is filtered separately in each zone by each air handler rather than at one central location.
Recap on the main benefits of mini VRF:
- precise zoning
- maximum energy savings
- requires only single phase electricity
- some systems can heat & cool simultaneously
- fewer breakdowns/less downtime
- advanced controls
- quieter outdoor & indoor units, even quieter than standard split systems
- offers configurations & features not possible with any other type of hvac systems
- requires less space & offers greater fexibility
- healthier indoor air
Types of Ductless Heat Pump Systems:
- mini split
- multi split
Types of VRF Systems
- cooling only
- heat pump (HP): cools & heats one at a time
- heat recovery (HR): cools & heats simultaneously
- single phase powered mini VRF: up to 8 air handlers on a single outdoor unit
- three phase powered large commercial VRF: up to 48 air handlers on a single outdoor unit
Other Points to consider about Mini VRF
- Higher upfront costs for equipment & installation: VRF HVAC systems are top of the line systems with cutting edge technology designed for improved comfort & maximum energy savings. Upfront costs can run 2 to 2.5 times as much as traditional systems. Often these costs are quickly regained since energy savings average 20-65% (Most systems achieve 20-30% savings). VRF can be very cost effective for new construction or where old systems are being replaced. Systems can average an upfront cost of $12-$18 per square foot depending on variables like control options & code requirements. Additional costs could include supplemental heating or a DOAS.
- Some VRF setups require a (DOAS) dedicated outdoor air system to meet ventilation codes. This brings in outside air into the zones. Buildings with operable windows usually are not subject to such code requirements. A DOAS & or ceiling fans can also further improve savings by increasing air distribution.
- Supplemental heating units are generally required for VRF systems: This is especially so in places like New York city where cold temperatures can reach extremes. On the very coldest days a VRF system is going to need supplemental heating to quickly heat a space. Home and businesses typically integrate electric heaters or radiant floor heating as a supplement.
- Installation requires VRF manufacturer trained & certified technicians. Manufacturer warranties require this. Proper installation & routine maintenance according to manufacturer’s exact specifications will ensure full operating efficiency & minimal repairs. Refrigerant leaks in joints can be difficult to detect so making sure the system is properly installed & commissioned from the beginning is very important.
Common VRF (Variable Refrigerant Flow) Manufacturers
Mini VRF systems offer energy savings & design flexibility which can make it the ideal choice for many buildings in New York City. Contact Gemini Thermo HVAC today for a free estimate. 718-690-3718