Do I need a permit for hvac replacement or installation in Unincorporated Duplin County?

Yes. In North Carolina, hvac replacement or installation generally requires a permit, and Unincorporated Duplin County is no exception.

Across North Carolina, an HVAC changeout requires a mechanical permit and must be performed by a state-licensed heating contractor; it is not covered by the NCGS 160D-1110 minor-work exemption because it is mechanical work. Any new electrical circuit or gas line associated with the equipment requires the corresponding trade permit. Duplin County's own permitting office is the Duplin County Building Inspections office, reachable on 910-296-2124 at https://www.duplinnc.gov/182/Building-Inspections. It issues permits for the unincorporated county. If your city does not run its own building department, this is the office that will handle the job, and that is more common in North Carolina than most states: the county is often the building authority even inside city limits, with the city handling only zoning. A change-out is normally a mechanical permit, and gas fired equipment usually adds a second permit and a pressure test. NCGS 160D-1110(c)(3) excludes replacement of heating and air conditioning equipment from the $40,000 exemption, so an HVAC change-out in unincorporated Duplin County needs a mechanical permit from Duplin County Building Inspections. In a Special Flood Hazard Area, Duplin UDO Section 1119(D) requires new HVAC equipment at or above base flood elevation plus 2 feet. A maintenance replacement that is not part of a substantial improvement may go in the original location. Duplin County publishes a Duct Air Leakage Test form and a Visual Air Form on its Building Inspections page for mechanical work.