An office conversion changes the building's electrical loads, roof or pad loads, vertical paths, refrigerant piping and condensate routes. Refrigerant piping length, elevation and total charge are limited by the manufacturer and by safety standards such as ASHRAE 15, especially with A2L refrigerants. Electrical feeder, panel and structural work belong to responsible licensed parties named in the scope, not to the mechanical contractor.
- Conversion moves load around the building. Check power, roof, shafts and ceilings together, not one at a time.
- Piping length, elevation, branch layout and total refrigerant charge are design limits, not installer preferences.
- A2L refrigerants bring flammability considerations. ASHRAE 15 and the current California Mechanical Code govern how much refrigerant a space can safely hold.
- Condensate from many indoor units needs a real drain plan, with pumps only where gravity cannot work.
- Electrical feeders, panels, structure and roofing must each have a named, licensed responsible party before bid.
Who owns each part of the work
Conversion scopes go wrong at the edges between trades. Everyone assumes someone else is handling the panel, the roof framing or the core drilling, and the gap shows up during construction. A scope should assign every item to a named party before bidding starts.
Davinci Mechanical's own UA Local 250 crew performs mechanical, refrigeration and controls work, with no subcontractors. A crane truck, if needed, is rented and coordinated by Davinci. Davinci does not perform primary electrical service, feeder or panel work, structural engineering or framing, or roofing. Those items must be assigned to responsible licensed parties, and the owner or general contractor should confirm who they are in writing. Our page on self-performed work lays out the policy.
| Item | Typical responsible party | Note |
|---|---|---|
| Outdoor units, refrigerant piping, indoor units, controls wiring to units | Mechanical contractor (Davinci for its scope) | Includes startup and commissioning of the mechanical system |
| Service and feeder upgrades, new panels, breakers, disconnects and power wiring | Licensed electrical contractor | Mechanical drawings give loads; the electrical party designs and installs |
| Roof framing, curbs, equipment supports and anchorage | Structural engineer and responsible contractor | Confirm who approves loads and who builds supports |
| Roofing penetrations and flashing | Roofing contractor | Protects roof warranty and watertightness |
| Fire-stopping, core drilling and shaft modifications | General contractor or responsible licensed party | Often needs inspection sign-off |
| Ceiling and finish repair | General contractor | Must be coordinated with indoor unit locations |
Power and panel capacity
A conversion changes the electrical picture in several ways. Large rooftop units come off their dedicated circuits. Outdoor units go on new circuits, sized to the manufacturer's data. Dozens of indoor units each need power, either from the outdoor unit's communication and power arrangement or from local circuits depending on the product. New ventilation equipment adds more load.
Sometimes the building's peak demand drops, sometimes it rises, and sometimes the load simply lands on different panels. The only way to know is to compare the old and new load schedules against the existing service and distribution. That is electrical engineering work for the responsible licensed party.
- Service capacity. Confirm that the main service can carry the new equipment along with the building's other loads. Utility coordination, such as with SCE, LADWP or SDG&E depending on the location, can add lead time if the service changes.
- Panel space and breakers. Check that existing panels have physical room and rated capacity, or that new panels are in the electrical scope.
- Disconnects and locations. Outdoor units and indoor-unit isolation typically need accessible disconnecting means. Confirm the current electrical code requirements.
- Phasing and voltage. Match the equipment's required voltage and phase with what the building provides.
- Communication wiring. Low-voltage control and communication cabling follows its own rules and is usually coordinated by the controls scope. See zoning and controls after an office conversion.
Contractor will furnish and install the mechanical, refrigeration and control components described in this scope and will provide equipment electrical load data to Owner's electrical designer. Primary electrical service, feeders, panels and breakers up to the equipment disconnects are performed by the licensed party designated by Owner or general contractor and are not included in Contractor's scope. Owner or general contractor to confirm the responsible party before award.
Roof loads, curbs and equipment locations
The roof you have was framed around the rooftop units it carries. A conversion can lighten the load, shift it, or both. Removing several large units and their curbs frees capacity in some places, while outdoor units, piping supports and walkways add weight and penetrations elsewhere.
- Where the weight goes. Outdoor units sit on rails or frames over structural members. The structural engineer determines acceptable positions and supports.
- Existing curbs. Old curbs left behind need a plan: removal and roof patching, or reuse as pipe or equipment supports. Both are roofing and structural decisions.
- Roof age and warranty. New penetrations on an aging roof, or one under warranty, should be coordinated with the roofing contractor before anything is cut.
- Clearances. Outdoor units need airflow around them and service access. Packing units tightly to save space can cause recirculation and high-pressure faults.
- Crane and rigging. Removal of old units and placement of new ones involve rigging plans and crane access. See our scope for equipment removal, crane and rigging.
- Alternative locations. Ground pads, mechanical yards and parking-structure platforms can solve roof limits, with their own security, noise and zoning issues.
Any claim about what a roof can carry has to come from a qualified structural professional. A mechanical contractor can supply equipment weights and dimensions, but should not be asked to approve the structure.
Shafts, chases and ceiling routes
Refrigerant piping is small compared with ductwork, but it still has to get from the roof or yard to every indoor unit. In a multi-story office that usually means vertical shafts or chases. Existing duct shafts can sometimes be reused, though fire ratings and access have to be reviewed.
- Vertical routes. Verify that shafts have room for insulated piping, support, and service access. Do not assume space freed by removing ducts is usable.
- Horizontal runs. Ceiling plenums are crowded with sprinklers, electrical, data and existing ducts. Piping needs slopes, supports and clear routes.
- Penetrations. Floors and rated walls need proper fire-stopping, which is a code matter involving the responsible licensed party and inspection.
- Exterior routes. Where interior paths are blocked, exterior piping on walls or roofs is possible, with weather protection and appearance concerns.
- Access panels. Branch boxes and valves need accessible locations. Burying them behind hard ceilings invites future trouble.
Refrigerant piping length and elevation
Every VRF and multi-zone product has published limits on total piping length, the longest run from outdoor to indoor unit, the elevation difference between outdoor and indoor units, and the elevation difference between indoor units. Those limits come from oil return, pressure drop and capacity. They are design inputs, and exceeding them is a design failure, not something to fix in the field.
| Question | Why it matters |
|---|---|
| How long is the longest run from outdoor unit to the farthest indoor unit? | Capacity falls and oil return becomes harder as lines get longer |
| What is the vertical separation between outdoor and indoor units? | Outdoor units on a high roof serving low floors, or the reverse, hit elevation limits |
| Where do branches and headers go? | Branch placement affects balance and must follow the manufacturer's rules for orientation and distance |
| How are line sets supported and insulated? | Condensation, vibration, UV exposure and mechanical damage all shorten life |
| Where are the joints and how are they tested? | Brazed joints in concealed spaces are the main leak path; pressure and vacuum procedures must be followed and recorded |
| Can the building be split across several systems? | Splitting into smaller circuits can bring each within limits and improve redundancy |
Good installations document the as-built piping with lengths, sizes, branch locations and pressure test results. Those records help with every later service call, and they can be stored with the asset records in the DaVinci Portal.
Refrigerant quantity and A2L safety
A building-wide refrigerant system has a large total charge, and the amount that could enter a single occupied room if a leak occurred is a safety question. ASHRAE 15, together with the California Mechanical Code and manufacturer instructions, sets how refrigerant quantity relates to room volume, occupancy and ventilation. Confirm the current adopted editions and local amendments for your project.
Many new systems use A2L refrigerants such as R-32 or R-454B. They are classed as mildly flammable, with low toxicity. Their use brings additional design attention: allowable charge relative to room size, leak detection or mitigation in some cases, ventilation, ignition-source considerations and technician training. Requirements are evolving, so verify current rules and product listings rather than relying on any general summary.
- Small rooms with large indoor units. The smallest room served by a refrigerant circuit often sets the limit. A design that looks fine overall can fail at one closet-sized office.
- Leak detection and shutoff. Some designs require refrigerant sensors and valves or other mitigation. These affect cost, controls and maintenance.
- Mechanical rooms and shafts. Where piping runs through enclosed spaces, ventilation and detection may be relevant.
- Technician qualifications. EPA Section 608 certification applies to refrigerant handling, and A2L work involves additional procedures and tools. Our refrigerant compliance guide covers the broader California picture.
- Records. Keep charge calculations, leak test results and any mitigation settings with the project documents.
Condensate from many indoor units
Each indoor unit produces condensate, and in a building with dozens of units that adds up to a network of small drains. Gravity drains need slope that the ceiling space may not offer. Condensate pumps solve the problem but add a powered component that can fail, overflow or be forgotten.
- Plan the drain route unit by unit during design, and verify slopes where tiles hide the pipe.
- Where pumps are used, include overflow safeties that stop the unit and, if possible, alarm to the controls.
- Provide cleanout access, and make sure insulation prevents sweating on cold lines.
- Confirm where condensate discharges, and whether local plumbing rules apply to the connection.
- Add all drains and pumps to the preventive maintenance scope. Water through a ceiling is a leading cause of tenant complaints in ducted and cassette systems.
The permitting and incentive side of these projects has its own page: Title 24, permits and incentives for office conversions. For a broader view of how the work is bid and staged, see VRF installation scope of work and phasing an HVAC conversion in an occupied office.