VRF and VRV aircon: between a multi-split and a chiller
VRF and VRV appear on maintenance contracts and tender documents, rarely with an explanation attached. Both name one system class. What separates it from the multi-split in a flat is not the size of the machine, it is how the refrigerant gets allocated.
By Team Snowflake | Updated 5 Aug 2026
What variable refrigerant flow means in practice
VRF describes an arrangement where one outdoor unit serves many indoor units, and the refrigerant reaching each indoor unit is varied continuously. Every indoor unit carries its own electronic expansion valve. That valve opens and closes against what its room is asking for, moment by moment, rather than sitting at one setting.
The outdoor unit varies along with them. A variable-speed compressor changes its own output to match what the indoor units are drawing between them, so the system settles at whatever share of its capacity the building currently wants. Nothing is switched wholly on and wholly off to hold a temperature.
The difference fits in one line: capacity is allocated, not divided. A multi-split system also hangs several indoor heads off one outdoor unit, and a separate guide covers that architecture. What it does not do is redistribute output between those heads while they are running. This class does, and that is what holds it up across a floor plate.
Scale follows from the same property. Systems in this class take many more indoor units on one outdoor unit than any residential product, across floors and along pipe runs far longer than a flat contains. The indoor units are also free to differ from each other.
VRV is Daikin's name for the same idea
VRV is a Daikin trademark. Daikin brought the arrangement to market first and registered a name for it, so its own equipment is sold as VRV while the rest of the industry sells VRF. Both words point at the same system class.
That is why paperwork mixes them. A tender can specify VRF, the equipment delivered can be branded VRV, and the maintenance contract can use either word on any given page. Read them as one thing. The trademark tells you whose equipment is on site, not what kind of system it is.
The distinction earns its keep in one place. Where the documents say VRV, the spares, the controller software and the service tooling are Daikin's, and that narrows the list of contractors who can properly work on it.
Mixed indoor formats on one circuit
One circuit can carry indoor units of different formats and different capacities. A boardroom takes a ceiling cassette, a corridor takes a concealed ducted box, a small store room takes a wall unit. All of them report to the same outdoor unit and draw on the same refrigerant supply.
That flexibility is why the class suits fit-outs. Tenancies change shape and partitions move. Adding or relocating an indoor unit becomes a change to one branch rather than a new system, as long as the outdoor unit has capacity and a spare connection point.
The ceiling on that is the outdoor unit's connection allowance, which is the same arithmetic every multi-split system is held to. The reasoning behind that allowance is set out on the multi-split page and is not repeated here.
Why varying the flow is what makes building scale work
Rooms in one building sit at very different loads at the same moment. A meeting room fills up and its load jumps. A west-facing office bakes through the afternoon. A store room asks for almost nothing all day. In a flat those differences are small. Across a floor plate they are not.
A system that divides its output crudely suffers under that spread. Something has to give when one zone demands far more than its neighbours, and what gives is usually the zone furthest from where the output is being taken. Varying the flow answers it by sending refrigerant towards the units calling for it and away from the ones that are not.
So a heavily loaded zone and an idle one can share a circuit without either dictating the other's outcome. That property is what the class is bought for. It is what lets one outdoor unit be responsible for a whole floor rather than one household.
Part load is where the running cost shows up. Cooling demand in a building spends most of its life below the peak the equipment was sized for. A compressor able to hold a partial output runs steadily at that output. One that only knows on and off has to cycle instead, and cycling costs efficiency and wears the parts that start and stop.
| What the building is doing | What a crudely shared system does | What varying the flow does |
|---|---|---|
| What the building is doingOne zone fills up while the rest sit empty | What a crudely shared system doesOutput is spread the way the design set it | What varying the flow doesRefrigerant is redirected towards the busy zone |
| What the building is doingDemand across the floor drops off in the evening | What a crudely shared system doesThe compressor cycles on and off to hold temperature | What varying the flow doesThe compressor holds a lower steady output |
| What the building is doingA tenancy is refitted and a zone changes shape | What a crudely shared system doesCapacity stays where the original layout put it | What varying the flow doesAllocation follows the new demand without rework |
| What the building is doingOne indoor unit is switched off entirely | What a crudely shared system doesIts share is not usefully recovered | What varying the flow doesIts flow closes and the rest becomes available |
| What the building is doingEvery zone calls at once on a hot afternoon | What a crudely shared system doesRooms furthest from the supply fall behind first | What varying the flow doesThe outdoor unit still meets its own ceiling |
Where varying the flow stops helping
The outdoor unit has a rating, and a hot afternoon with every zone calling will find it. Varying the flow decides who gets what while there is something left to allocate. It does not manufacture capacity that was never installed.
Design assumptions carry the same weight here as anywhere. A system sized around an office layout that has since been cut into twice as many rooms is serving an occupancy that no longer exists. The complaint arrives as poor cooling in whichever rooms sit furthest along the pipe run, and no amount of control logic corrects an outdoor unit that is too small.
Treat a recommendation to top up the gas on a system that only struggles at peak with some caution. Ask first whether the same rooms fall behind when the floor is quiet. If they hold up fine then, the finding points at capacity and layout rather than at charge, and a top-up buys nothing.
Where VRF sits between a multi-split and a chiller
Three arrangements cover most of what is cooled in Singapore, and this class is the middle one. A split or multi-split serves one household from one outdoor unit. A VRF system serves a floor, a shophouse or a whole small building. A central chilled-water plant serves a tower, or several towers on a district supply.
What separates it from the plant above it is the medium, not the size of the building. This class is refrigerant-based. Refrigerant is made cold at the outdoor unit and piped, still as refrigerant, all the way to the coil in the occupied room. A chilled-water plant makes cold water centrally and sends water up risers to coils in the space. Which circuit feeds a given coil is worked through on the fan coil unit page, and the consequences named there apply here too.
Distribution is the other dividing line. A chiller gathers the machinery into one plant room, with risers, pumps and a regime built around that room. This class spreads out instead. Outdoor units sit on roofs, ledges and service decks close to the zones they serve, and one building often carries several independent systems that share nothing with each other.
Spreading out is what makes it attractive to a building too small to justify a plant room, and to a landlord who wants each tenancy controlled and metered on its own. It is also why the class turns up where a chiller never would. A shophouse converted into offices, a two-storey clinic, a mid-sized retail unit and a large landed house are all ordinary homes for it.
| What separates them | Against a multi-split | Against a central chilled-water plant |
|---|---|---|
| What separates themScale of what one system covers | Against a multi-splitA floor plate or a building, not a household | Against a central chilled-water plantA zone or a building, not an estate |
| What separates themHow the cooling reaches the room | Against a multi-splitMetered per indoor unit and varied while running | Against a central chilled-water plantRefrigerant to the room, not water to a coil |
| What separates themWhere the machinery stands | Against a multi-splitSeveral outdoor units rather than one | Against a central chilled-water plantSpread near the zones, not held in a plant room |
| What separates themWho owns the equipment making the cold | Against a multi-splitThe occupier owns both ends, as in a flat | Against a central chilled-water plantThe occupier owns it, rather than the building |
| What separates themWhat a single fault interrupts | Against a multi-splitThe zones on that system, not one bedroom | Against a central chilled-water plantOne system, not every floor at once |
Refrigerant reaching the room has consequences
Piping refrigerant into every occupied space means a large charge spread over a long run. A split in a flat holds a small charge in a short loop. A system of this class holds a great deal more, distributed through risers, ceiling voids and branch fittings across a floor.
Two things follow from that volume. A leak has more places to hide, and it has more to release when it is found. Refrigerants also carry limits on how much may enter a given room volume, so a large charge feeding small enclosed rooms is a question answered during design and commissioning, not one to discover at repair time.
A chilled-water building sidesteps the issue by keeping refrigerant inside the plant room and sending water out to the space. That is a genuine trade rather than a selling point, and it is one reason the two classes are maintained by different sorts of contractor.
Branch boxes and refnet joints: the hardware that splits the line
One pair of pipes leaves the outdoor unit and has to become many. The fitting that performs the split is where this class differs physically from anything in a flat, and it is the part to understand before a fault makes it urgent.
Branch fittings are the common answer. These are Y-shaped joints and headers brazed into the pipe run, dividing one line into two, then dividing again further along. They carry no power and no controls. Their job is to split the flow so that refrigerant and oil keep moving properly down each leg. Refnet is Daikin's word for its own fittings, and the trade tends to use it loosely for all of them.
A branch box is the other approach. It is a housed unit sitting between the outdoor unit and a group of indoor units, holding the valves that meter each branch, with power and control wiring run to it. Where a system uses one, the metering has been lifted out of the indoor units and gathered into a single place.
Where this hardware sits decides how a fault gets handled. Joints and boxes live above false ceilings, inside risers and along service corridors, and they are often sealed behind finished plasterboard once the fit-out completes. Tracing a leak across a distributed run is slow work in the best case, and slower again when the fittings sit behind a ceiling nobody has opened since handover.
Ask for the as-built drawing before anybody needs it. It records where the joints, boxes and isolation points are, and which indoor units sit on which branch. Buildings lose these at handover and lose them again at every change of managing agent. A contractor searching a system without one is charging for the search.
- The as-built drawing, showing pipe routes, branch fittings and isolation points.
- The indoor unit schedule, listing each unit by room or zone with its address on the system.
- Access notes: which ceiling panels open, and where the sealed sections run.
- The commissioning report, including the refrigerant charge the system was filled to.
- The controller documentation, and whatever login the system was handed over with.
Access is the cost nobody quotes for
Reaching the hardware often costs more than repairing it. Opening a sealed ceiling, working around occupied hours and making good afterwards are all real work, and they attach to the building rather than to the fault itself.
Have them named separately in any quote. A figure that covers the repair but says nothing about access is not the figure the job will finish at, and the gap tends to surface once the ceiling is already open.
What owning one actually changes
Servicing moves from ad hoc to contracted. A household calls somebody when the aircon stops. A building on this class runs a maintenance contract, with scheduled visits, a named contractor and condition recorded against each unit. The reason is practical. A system with many indoor units and a long distributed run degrades quietly, and nobody is standing in every room to catch it.
Faults are read through a controller rather than off a blinking light. Centralised controllers list units by address and report fault codes against them, so the first news of a problem is a code and a unit number on a screen in an office or a lobby. That changes who notices first, and it changes what the contractor is handed to work from.
A refrigerant leak is a far bigger event than it is on a split. The charge is larger, the run is longer, and the loss reaches every indoor unit on that circuit rather than one room. Recovering, repairing, pressure-testing, evacuating and recharging a distributed system is a different order of job from the same sequence in a flat, and the space usually has to be handed over while it runs.
Watch for the quote that treats a system this size like a split. Putting the charge back without finding where it went sends the same volume out through the same hole, and the symptoms return in the same rooms. On a distributed run the leak search is the job. The top-up is only what happens once it succeeds.
| What changes | On a split or multi-split | On a system of this class |
|---|---|---|
| What changesHow servicing gets arranged | On a split or multi-splitCalled in once something has gone wrong | On a system of this classContracted, scheduled, recorded unit by unit |
| What changesHow a fault first surfaces | On a split or multi-splitSomebody in the room notices it | On a system of this classA code against a unit address on a controller |
| What changesWhat a leak takes to resolve | On a split or multi-splitOne short loop to trace and repair | On a system of this classA distributed run, and the space handed over |
| What changesWho holds the spares and the tooling | On a split or multi-splitMost aircon contractors carry them | On a system of this classContractors set up for that manufacturer |
| What changesWhat is out of action during the repair | On a split or multi-splitOne room, or one flat | On a system of this classEvery zone on that system together |
The useful question is who maintains it, not how to fix it
This is a class of system that needs a contractor set up for it. Manufacturer training, controller software, service tooling and access to spares are all specific to the equipment, and a system still under warranty normally names who is permitted to touch it. An owner who inherits one is not choosing between fixing it and calling somebody.
So the questions worth asking are contractual rather than technical. None of them require any knowledge of refrigeration, and the answers say a great deal about how well the system is being looked after.
- Who holds the maintenance contract, and what a scheduled visit includes.
- What sits outside it: parts, refrigerant, access work, attendance outside operating hours.
- Who attends when a zone fails between visits, and how that attendance is charged.
- Whether the manufacturer's warranty names an approved contractor for the site.
- Which obligations fall to the landlord and which to the tenant.
- Where the as-built drawing, the commissioning report and the controller access are kept.
Settle it before a floor goes warm
The worst version of this conversation happens with a floor already warm and nobody able to say who is responsible for the system serving it. Contracts get inherited with buildings, and the paperwork rarely arrives with the keys.
Establish the answers while everything is running. An owner or tenant who can name the contractor, produce the drawing and describe what the contract covers has removed most of the delay from a future fault. That is worth more on this class of system than knowing what any individual component does.
Ready to get started?
Tell us what’s going on. Symptoms, setup, photos, anything we should know. We’ll assess and come back with the right next step.