Rooftop Unit Replacement Without Permit Drawings
A property manager wants to swap a 12-year-old, 8-ton packaged rooftop unit serving a small office building with a new unit of the same nominal capacity. The mechanical contractor submits for a permit with only a one-line equipment schedule and a manufacturer cut sheet. The existing unit sits on a curb; the new unit is 3 inches taller and 200 lb heavier. The building official's plan reviewer notices the submittal does not show the curb adapter, the gas piping connection, the condensate routing, or the electrical disconnect. The contractor argues that because the capacity and occupancy are unchanged, this is a like-for-like replacement that needs no detailed drawings. The plans examiner must decide whether to issue the permit as submitted, request additional information, or reject it outright.
1. Should the plans examiner issue the permit on the basis that this is a like-for-like replacement? Explain the reasoning a code official would apply.
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No. A permit application is not judged solely on whether capacity and occupancy are unchanged. The reviewer must confirm that the proposed work will comply with the code as a whole, and that determination depends on information the applicant has not supplied.
Key points a code official would consider:
- Scope of review: The reviewer cannot verify structural support of the curb, clearances, combustion air, gas piping sizing, condensate disposal, or electrical connections without drawings or data. A missing detail is not the same as a compliant detail.
- Changed physical characteristics: The new unit is heavier and taller. That triggers questions about curb/structural adequacy and about clearances to the roof surface and adjacent equipment, which must be documented.
- Administrative duty: The correct action is to request the missing information (curb adapter detail, gas piping and sizing, condensate routing, disconnect and overcurrent protection, clearances), not to reject outright and not to approve on assurances.
- Like-for-like is not a code category: The code does not exempt replacements; the permit process exists to verify compliance of the actual installation.
2. The contractor later installs the unit with a field-fabricated curb adapter and no condensate trap. Which items should the inspector cite, and how should the inspector handle the approval?
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The inspector should not grant final approval. Two independent deficiencies are present:
- Curb adapter: A field-fabricated adapter must be shown to support the unit and maintain the required clearances and weathertightness. The inspector should require documentation or listing for the adapter, or evidence that it is structurally adequate and sealed. If the adapter raises the unit, verify clearances to the roof and to any adjacent units are still maintained.
- Condensate trap: A draw-through cooling coil operating under negative pressure requires a condensate trap of adequate depth, properly sized and installed, to drain. Without a trap, the unit will not drain and will carry water, promoting corrosion, biological growth, and overflow. The inspector should cite the missing trap and require it before sign-off.
Process: Issue a correction notice listing both items, require re-inspection after correction, and document the deficiencies. Final approval should be withheld until both are corrected and verified.