Most high-rise buildings in Vietnam run on VRF: one outdoor unit on the roof, many indoor units in the apartments, joined by two copper lines and a condensate pipe. Modelling that is MEP work, and the thing that usually blocks people is not the drawing itself but two questions: where do the families come from, and what system do you draw the refrigerant pipe with.
This article answers both on Revit 2027. VRF in Revit has no dedicated tool: indoor and outdoor units are Mechanical Equipment, refrigerant and condensate are Pipe, and what decides everything is the connectors on the family. To learn the whole HVAC workflow on one building, see the Revit MEP course.
VRV, VRF and FCU in Revit
Three terms that get mixed up, and in Revit they lead to three different ways of modelling.
| Term | What it is | In Revit |
|---|---|---|
| VRV / VRF | Variable refrigerant flow: outdoor and indoor units joined by refrigerant pipe | Mechanical Equipment + pipe on the Other system |
| Chilled-water FCU | An indoor unit fed with chilled water from a chiller | Mechanical Equipment + Hydronic Supply and Hydronic Return |
| DX indoor unit | Direct expansion coil, the kind used in a VRF system | A Fan Coil Unit family with the DX suffix |
VRV is one manufacturer's trade name and VRF is the generic one. English searches use vrv revit or fcu revit, while Revit itself uses neither: to the software these are mechanical equipment with duct, pipe and electrical connectors.
The file to follow along with
You need an MEP file with an architectural model linked in and a typical floor plan. The article on the Revit MEP sample file shows how to take the Institute's sample file and link the Snowdon Towers architectural model that ships in the Samples folder of Revit 2027.
The screenshots come from a residential floor: a central corridor, apartments on both sides, suspended ceilings in the rooms.
Where the revit fan coil unit families come from
Start by checking what the file already has. Typing into the Project Browser search box answers that in a second.
Most templates carry no indoor units at all. There are three sources, and this article uses the second because it ships with every installation.
| Source | What you get | Note |
|---|---|---|
| The families already in the file | Generic equipment, sometimes only an AHU | Fastest; check with the Project Browser search box |
| Load Autodesk Family | Autodesk's online content, including indoor units | Needs a sign-in and a connection |
| Manufacturer content | The right model, size and capacity | Download from the manufacturer; check the connectors first |
Step 1. Open the plan of the floor you are equipping.
Step 2. Run Insert › Load from Library › Load Autodesk Family.
Step 3. Type fan coil in the search box and press Enter. The dialog returns 17 results, all under Mechanical › MEP › Air-Side Components › Terminal Units: Fan Coil Unit - Ceiling Ducted, - Horizontal, - Horizontal DX, - Vertical, - Vertical Stack and the versions with a plenum.
Step 4. Pick Fan Coil Unit - Horizontal - DX and click Load. DX means direct expansion, which is exactly what a VRF indoor unit is.
Typing VRF into the same box returns nothing at all. Autodesk's online library carries no ready-made VRF indoor units, so a family with a real model name has to come from the manufacturer.
Typing split system returns four results, among them Heat Pump - Split System, which suits an ordinary two-part unit. A revit fan coil unit downloaded from a file-sharing site should always be opened and checked first: many such files are just shapes with no connectors.
Placing a fcu revit indoor unit and reading its connectors
Step 5. Type ME (Mechanical Equipment). Properties switches to placement mode and the Type Selector shows the family you just loaded.
Step 6. Choose the type Fan Coil Unit - Horizontal - DX / 200 CFM. The Mechanical group of Properties already tells you what this machine carries: Refrigerant Flow, External Static Pressure, Drain Flow, and a System Classification listing the kinds of connector on it.
Step 7. Set Offset from Host to the height at which the unit hangs inside the ceiling, then click the position in plan.
Step 8. Select the unit you placed and read Properties. Besides the elevation, four figures are worth scheduling: Nominal Air Flow, Refrigerant Flow, Drain Flow and External Static Pressure.
Reading the connectors is what decides the system your pipes will belong to. Revit 2027 shows connector information in the view as soon as the equipment is selected, so you no longer have to open the family to find out.
Step 9. With the unit selected, read the three connector groups: one rectangular duct connector 406.4 × 158.8, two 15.9 mm pipe connectors and one electrical connector at 120 V - 50 VA. The System Classification of the unit lists all three families of system behind them: Supply Air for the duct, Other for the refrigerant pipes and Sanitary for the condensate.
The two 15.9 mm connectors are the liquid and gas lines of the VRF system. On a real machine the two differ in diameter; manufacturer families carry the right sizes per model, library families use one size for both.
Drawing the refrigerant pipe: right-click the connector
Step 10. Right-click one of the pipe connectors. The menu offers the commands that start from the connector itself: Draw Pipe, Draw Pipe Placeholder, Draw Flex Pipe, Cap Open End, Create Piping System, Add to System, Remove from System.
Step 11. Choose Draw Pipe and click the end point. The pipe starts at the centre of the connector, at the elevation of the machine, with nothing to align by hand.
Step 12. Select the new pipe and read the Mechanical group. Its system comes from the connector: System Classification Other, System Type Other, and Revit names the new system Other 1.
That answers the question of which system carries a refrigerant pipe: Other. Revit's list of piping classifications is fixed, with no "Refrigerant" entry to add, so every refrigerant line lives under Other. The work to do is to split the two runs: duplicate the Other system type into two system types, name them for the liquid and the gas line, and give each its own colour and abbreviation.
One more thing to change: the pipe type. Revit uses whichever Pipe Type is current — uPVC in the sample file, a water material. Refrigerant lines are copper, so create a copper pipe type before drawing, the way the article on pipe types in Revit describes.
Condensate and the outdoor unit
The second pipe connector on the indoor unit is the condensate drain, and it connects the same way: right-click, Draw Pipe. The difference is that condensate has to fall towards the drain, so set the slope before you draw. Slope and invert level annotation are covered in sloped sanitary pipe in Revit.
The outdoor unit is no different in principle: still Mechanical Equipment, placed on a roof or plant deck, with the refrigerant lines running up to it. For the vertical run, Revit 2027 adds a Create Riser button on the ribbon while you are placing pipe, duct, cable tray or conduit, as described on Autodesk's What's New page.
Modelling VRF in Revit stops there: Revit does not size refrigerant pipe for you. Line sizes, equivalent lengths and the permitted height difference come from the manufacturer's selection software. The Revit model holds the geometry and the data for coordination, quantities and drawings.
From CAD
| In CAD | In Revit 2027 |
|---|---|
| The indoor unit is a two-line block | A family with duct, pipe and electrical connectors |
| Refrigerant lines are two polylines | Real pipes with size, elevation and a system |
| The condensate slope is a note | Slope is a property of the pipe, tagged straight from the model |
| Units counted by hand | The equipment schedule adds them up |
CAD users coming to VRF in Revit usually ask where to find an air-conditioning block library. The Revit equivalent is a family, and the three sources above answer it.
When it does not work
| Symptom | Cause | Fix |
|---|---|---|
| The loaded family is not in the Type Selector | Another command is active, or the family is in a different category | Type ME and open the Type Selector; check the category in the Project Browser |
| Right-clicking a connector shows no Draw Pipe | The equipment is not selected, or you clicked the body rather than the connector | Select the unit, zoom in and click the connector icon itself |
| The pipe comes out as uPVC or steel | The current Pipe Type belongs to a water system | Create and select a copper pipe type first |
| Both refrigerant lines share one colour | They both use the Other system type | Duplicate the system type and give each line its own name and colour |
| The condensate pipe is flat | No slope was set before drawing | Set the slope on the ribbon and redraw the run |
| A manufacturer family will not connect | The family has no connectors, only geometry | Open the family and add connectors, or use another family |
Three things people often get wrong:
| What you often hear | What Revit 2027 actually does |
|---|---|
| Revit ships with the manufacturers' VRF families | The online library returns nothing for VRF; it has generic fan coil and split units |
| Refrigerant needs its own system classification | The classification list is fixed; refrigerant runs on Other and is split by system type |
| Revit can size refrigerant pipe | Line sizing comes from the manufacturer's selection software |
Frequently asked questions
Where do VRF indoor unit families come from?
Autodesk's online library has a Fan Coil Unit group whose DX version works as a VRF indoor unit. Families with real model names come from the manufacturer, and their connectors should be checked before use.
Which system do I draw refrigerant pipe with?
Other. That is also the classification carried by the refrigerant connector on the indoor unit, so a pipe drawn from the connector inherits it.
What system is the condensate pipe?
Sanitary, the same family as waste pipe, and it needs a slope.
Can the indoor unit take ductwork?
Yes. The duct connector on the library DX unit is 406.4 × 158.8; connect duct and diffusers as described in drawing ducts in Revit.
Does the indoor unit need wiring?
It carries a 120 V - 50 VA electrical connector, so it can join a circuit like any other device. Circuits are covered in circuits and wiring in Revit.
Related articles
- Drawing ducts in Revit — duct and diffusers for the indoor unit
- Pipe types in Revit — a copper pipe type for refrigerant
- Sloped sanitary pipe in Revit — slope for the condensate line
- What is Revit MEP — the three MEP systems in one model