Rooftop Package Units for Commercial Retrofits (3–30 Ton)

Replacing a rooftop unit is a construction project disguised as an equipment purchase. The unit is usually the cheapest part of the job; the crane, the curb, the duct transitions, the controls integration and the occupied-building schedule carry the risk. This guide is written for the contractor, distributor or facility engineer who has to specify and compare 3–30 ton rooftop package units — and who has to defend the choice in a submittal.

Everything numeric below comes from our published rooftop package units data. Where a number belongs on a unit-specific submittal sheet and is not published, this guide says so instead of guessing.

Step 1 — Define the scope before you select equipment

A rooftop retrofit is one of four projects. Decide which one you are doing, because it changes the equipment specification and the submittal.

Write the project type at the top of the specification. A “unit swap” priced as a “system upgrade” (or the reverse) is the single most common commercial mistake in this category.

Step 2 — Survey data you must have in hand

Do not accept a quotation against an address. Collect and record the following, and attach the data to the RFQ so the factory selection is built on facts.

A single site visit that captures all thirteen rows is worth more than three quotations that capture none.

Step 3 — Compare options on a like-for-like basis

Our published rooftop range is summarised below. Note the distinction between the standard range, the wider product line-up, and the deep-customised large-capacity category.

Build your comparison table with the same twelve to fifteen rows for every option you are considering, including the “keep and repair” option. Rows that decide most projects:

• Capacity at design conditions, not nominal tonnage. Two units rated at the same tonnage behave differently at your outdoor design temperature; ask for capacity at the project’s design entering conditions and record the basis.
• Airflow versus static pressure. A unit that meets the airflow figure at low static pressure may not meet it against your duct system. Record the static pressure the airflow figure was quoted at.
• Electrical service. Single-phase and three-phase options materially change the feeder, the disconnect and sometimes the available unit sizes. Confirm the building’s actual supply before selection.
• Refrigerant. R-410A and R-32 both appear in our published range. Do not mix designations, do not assume interchangeability, and confirm per model which refrigerant applies, along with the charge and the handling requirements for that refrigerant class.
• Control protocol versus control system. BACnet and Modbus are communication protocols, not certifications. What matters is whether the required points exist, whether they map to the building’s front end, and who commissions the integration.
• Maintenance access. Filter and coil access, fan and motor removal path, and whether the service technician can work without a crane. This is where the lowest first-cost option often loses.
• Partitioning strategy. For larger loads, several smaller modules can be staged for part-load operation and for staged replacement later. Compare total installed cost and part-load behaviour, not just first cost.

Step 4 — Model the cost as line items, not as a unit price

We do not publish prices, and a comparison based on equipment price alone will mislead you. Assemble the following line items from your own quotations, labour rates and crane costs.

Then normalise: cost per ton of installed capacity, and cost per unit of delivered capacity at design conditions. Both numbers make the comparison defensible.

Step 5 — What goes in the submittal

A rooftop submittal that clears review contains:

• Unit schedule by tag, with capacity at design conditions, airflow, static pressure, electrical data and refrigerant.
• Dimensioned drawings: footprint, connection sizes and positions, weight and centre of gravity, service clearances, and multi-section cabinet split points where applicable.
• Curb and transition details, including the adapter curb and the supply/return arrangement (same-side or cross-over).
• Fan and motor data with the selected drive, plus the VFD where specified.
• Filter schedule with MERV rating and the pressure drop the selection assumes.
• Controls points list with protocol (BACnet or Modbus), supported objects, and the integration responsibility matrix.
• Sound data where a limit applies.
• Certification and compliance documents: the certification mark and its status for the Canadian market, and the energy-efficiency reporting information the importer needs.

On that last point, be explicit with your supplier. Regulated energy-using products have federal energy-efficiency requirements and a reporting obligation at import; the dealer files an energy efficiency report before importation, and the customs release document must carry specified product and purpose information. Our role is to supply the data; the dealer, and the certification status of the specific models, must be verified per order. Ask for the certificate name, number, issuing body, validity and covered model list, and for the Canadian “c” prefix on the mark.

Where the project is in Quebec, also confirm the French-language documents and markings that must accompany the product, and make sure the firmware and control graphics are addressed in the commissioning scope rather than after handover.

Step 6 — Sequence the crane day

Field failures cluster around installation day. A reproducible sequence:

1. Weeks ahead — structural review, curb condition survey, electrical isolation plan, refrigerant recovery plan for the old unit, tenant notice.
2. Days ahead — confirm crane position, rigging plan, weights, roof protection, and the delivery window; verify the new unit’s packaging and which sections arrive separately.
3. Day of — isolate and recover refrigerant from the existing unit, disconnect power and controls, lift out, inspect and repair the curb, set the new unit, verify level and gasketing.
4. Following days — duct transitions and flexible connections, electrical terminations, controls integration, filter and accessory installation, leak check and evacuation if split, start-up.
5. Close-out — commissioning, balancing, controls demonstration, as-built documentation, refrigerant record, warranty registration and spare-parts list.

Two points that are routinely skipped and routinely cost money: recovering and documenting refrigerant from the old unit under the applicable federal halocarbon requirements, and confirming that the crane and rigging plan accounts for the new weight and centre of gravity, not the old unit’s.

Common failure modes

• Curb mismatch discovered on the roof. Measure the curb, do not assume it. Adapter curbs ordered late delay the crane.
• Supply/return layout misread. Our units place supply and return on the same side. If the existing installation takes return from the opposite side, duct rework is in scope and must be priced.
• Static pressure overlooked. The unit is selected on nominal airflow and then cannot deliver it against the actual duct system. Recirculation, noise and comfort complaints follow.
• Electrical service assumed. Available fault current, breaker rating and conductor size are checked after the unit arrives. Sometimes this is the largest hidden line item in the project.
• Refrigerant designations mixed. Never present R-410A and R-32 as interchangeable. Confirm the refrigerant per model, the charge, and the handling rules for that refrigerant class — including where an A2L refrigerant is involved.
• Controls integration left to the end. A points list agreed after delivery guarantees a commissioning extension. Agree the list at order.
• Certification assumed from another market. A mark that is not valid in Canada is not evidence of compliance. Ask for the Canadian “c” prefix mark, the certificate details and the covered models.
• Compliance paperwork treated as an afterthought. Energy-efficiency reporting and the customs release information are prerequisites for import, not closing documents.
• No spares or service plan. Without a documented spare-parts route and a service contact, the first failure becomes an availability problem, not a repair.
• Contingency left out. Every rooftop project finds something — a rusted curb, an undersized feeder, a blocked drain pan. Carry a contingency.

What to confirm with your supplier

• Published capacity, airflow and electrical data for the specific model, at specified conditions, on a unit-specific submittal sheet. If a figure is not published, request it per model rather than accepting a range.
• Refrigerant type for the exact model, charge quantity, and the handling requirements that follow from that refrigerant class.
• Whether the unit is available in the configuration you need (inverter heat pump or on-off, single-phase or three-phase) and what the lead time is for factory options such as economizer, energy recovery, hot gas reheat, higher MERV filtration or higher static pressure.
• Certification mark details for Canada: certificate name, number, issuing body, validity and covered models — and whether the mark carries the “c” prefix.
• Energy-efficiency reporting data required for import, and who is responsible for filing.
• Dimensional drawings, weights, centre of gravity and cabinet split points for rigging.
• Controls documentation: protocol support, points list, and what commissioning support is provided.
• Spare-parts availability and response expectations for the Canadian market, stated honestly.
• Factory or remote start-up support, warranty terms and the warranty entity in Canada.
• For Quebec-bound projects, the French-language documentation and product markings that will be supplied.

Send the completed survey table and unit schedule with your request for quotation, and review our commercial equipment solutions and the A2L-ready hub if the project involves a refrigerant transition. The resources library carries the companion checklists for import documentation and refrigerant handling.