A VRF installation scope should name every outdoor module, branch selector box and indoor unit by schedule tag, define the refrigerant piping routes and joining method, require nitrogen-purged brazing, pressure test and evacuation with recorded results, state how additional charge is calculated and logged, assign communication wiring and power, and list commissioning deliverables. Gaps usually appear at the electrical boundary and at the roof.
- Tie the scope to a schedule: outdoor modules, branch selector boxes and indoor units each get a tag, a location and a mounting method.
- Piping is where VRF jobs are won or lost. Routes, lengths, elevation changes, insulation and joining method belong in writing before the bid.
- Nitrogen-purged brazing, a recorded pressure test and a recorded evacuation are the three records that matter most at closeout.
- Additional refrigerant charge is calculated from the installed line lengths, so the scope should say who calculates it and where it is documented.
- Power feeds, disconnects and structural support are usually other trades. The scope must name who performs them.
Draw the boundary before listing equipment
A VRF system touches more trades than a rooftop unit swap. The refrigerant circuit, the controls network, the electrical feeds, the roof or slab and the ceiling space all belong to someone. A scope that lists equipment but never says where each trade stops invites change orders later. If you are writing the overall document, start with the framework in how to write a commercial HVAC scope of work and then add the VRF specifics below.
Davinci's mechanical, refrigeration and controls work is performed by its own UA Local 250 crew with no subcontractors, and that covers the VRF refrigerant circuit, equipment setting and controls interface. Primary electrical service, feeders, panels, structural steel and roofing are not part of that crew's work, so the scope has to name who performs them and the owner or GC should confirm the responsible licensed party.
Equipment the scope should itemize
| Item | What to state | Common gap |
|---|---|---|
| Outdoor modules | Tag, location, pad or rail type, clearances, combined module count | Service clearance not confirmed against the roof layout |
| Branch selector boxes | Count, ceiling or chase location, access panel size, drain or isolation needs | Boxes placed above hard ceilings with no access |
| Indoor units | Type, tag, mounting, condensate route, controller type | Condensate termination left undefined |
| Refnet joints and headers | Supplied with the piping package or by the manufacturer | Fittings priced by one party and installed by another |
| Controllers and gateways | Local controllers, central controller, BAS gateway if required | Network points assumed but not listed |
Heat recovery systems use branch selector boxes to let one zone cool while another heats. Heat pump only systems do not. State which type is being installed, because the pipe count, box count and wiring differ.
Piping runs and brazing
Refrigerant piping is the longest line item in labor and the one most often described in a single sentence. Ask the scope to say more than "furnish and install refrigerant piping."
- Route and length: Reference the drawings or a marked-up plan showing risers, horizontal runs, and any elevation limits between the outdoor module and the farthest indoor unit.
- Material and sizing: Clean, capped refrigeration-grade copper, sized per the manufacturer's design software output, with the output attached or referenced.
- Joining method: Brazed joints with a continuous nitrogen purge flowing through the pipe while brazing, so oxide scale does not form inside the line.
- Insulation and protection: Insulation thickness, UV protection on exposed roof runs, and sleeves or firestopping where pipes pass through rated assemblies.
- Support and routing: Hanger spacing, pipe supports on the roof, and who provides penetrations and curbs for roof entries.
Firestopping at rated walls and floors is often performed by a separate trade or by the GC. Say so in the scope instead of leaving it implied.
Pressure test, evacuation and charge
- Nitrogen pressure test the completed piping to the manufacturer's stated test pressure, hold for the specified period, and record the start and end readings with gauge identification.
- Pull a deep vacuum with a calibrated micron gauge at the far end of the system, not at the pump, and hold to confirm the vacuum does not rise.
- Calculate additional refrigerant from the actual installed liquid line lengths and diameters, using the manufacturer's method, and compare it with the factory charge.
- Weigh in the additional charge, log the amount and the refrigerant type, and attach the calculation to the closeout record.
A tight pressure test is the cheapest leak repair you will ever perform. Treat the recorded test as a deliverable and not as a courtesy. Handling of refrigerant must follow EPA Section 608 practice, and the refrigerant compliance guide for California explains how recordkeeping fits in. Confirm current requirements for the refrigerant in use.
Communication wiring, controls and the electrical line
VRF systems run a low-voltage communication bus between the outdoor modules, branch boxes and indoor units. It is sensitive to wire type, polarity, shielding and termination. The scope should specify cable type, how it is routed away from power conductors, and who lands the shielded ends and addresses each device.
- Contractor: refrigerant circuit, communication bus between VRF components, unit addressing, controller programming, and the interface to the BAS gateway if one is specified.
- Electrical party named in the scope: power feeds, disconnects, breakers and fused protection, and any conduit to the outdoor modules and indoor units.
- Shared items to settle early: condensate pumps, drain routes to a code-acceptable point, and the location of the central controller.
For the building automation side, the building automation controls upgrade scope shows how to define integration points without overpromising.
A2L refrigerant considerations
Many current and upcoming VRF lines use A2L refrigerants such as R-32 or R-454B, which are mildly flammable. That changes what a scope should ask for. Design should check room volume and the system charge against ASHRAE 15 and the manufacturer's installation requirements. Some designs call for leak detection, mitigation controls or ventilation interlocks in smaller spaces.
The scope should state which refrigerant is specified, who performs the room-volume check, and whether mitigation devices are included. Rules on A2L adoption, local code amendments and the HFC transition continue to change, so confirm current CARB, EPA and local building department requirements before pricing.
Commissioning and closeout deliverables
Startup is more than powering up. Commissioning should include verifying each indoor unit communicates and responds, checking operating pressures and temperatures in cooling and heating, confirming condensate drains, and running the system long enough to see stable operation. Test and balance performed by a third-party agency is outside Davinci's work, so name that party if the specification requires it.
Closeout should hand over the pressure test record, the vacuum record, the charge calculation, the device address list and as-built piping sketches. Davinci can load asset records into the DaVinci Portal so each outdoor module and indoor unit has a QR-coded history. For a larger project, see bid projects and the VRF and split systems service page.
Contractor shall furnish and install the VRF outdoor modules, branch selector boxes, indoor units and refrigerant piping shown on the equipment schedule. Piping shall be brazed under a continuous nitrogen purge, pressure tested and evacuated with recorded results, and charged per the manufacturer's calculation using the installed line lengths. Power feeds, disconnects and structural supports are provided by others as identified by Owner. Contractor shall provide the test records and device address list at closeout.