New Hampshire HVAC Permit Requirements

Where state licensing applies, an OPLC license proves you are qualified. A municipal permit authorizes you to do the actual work. New Hampshire contractors who confuse the two discover the distinction when a building inspector shuts down their job site — state licensing and municipal permitting are separate systems run by separate authorities; AC-only work still requires the applicable local permit even when no state mechanical license is required.

The State vs. Local Jurisdiction Split

The OPLC Mechanical Licensing Board certifies professional competency. It determines who is qualified to perform gas fitting, plumbing, and related mechanical work statewide.

Municipal building departments control project-level permitting — they authorize specific installations at specific addresses, enforce the adopted building and mechanical codes, and conduct the inspections that determine whether a system can be permanently commissioned.

Performing work without the required local permit is a violation that can trigger:

• Municipal stop-work orders
• OPLC administrative fines under RSA 310:12
• Suspension of your individual and business licenses

How Permits Work in Most NH Municipalities

Before starting any HVAC installation, replacement, or modification, file the applicable mechanical or electrical permit application with the local building department. The application typically requires your OPLC license number, business entity license number, proof of insurance, a description of the work, and in some cases a plan or diagram.

After the permit is issued, you must schedule:

1. Rough-in inspection — before closing walls or concealing ductwork
2. Final operational inspection — the local inspector verifies code compliance before the system can be permanently commissioned

The system is not legally complete until the inspector signs final approval.

Manchester HVAC Permits

The Manchester Building Division separates mechanical permits into "Mechanical (fuel-gas)" for licensed gas fitters and "Mechanical (non-fuel gas)" for standard ductwork and electric cooling systems.

Residential fee schedule:

• 1 dwelling unit: $40
• 2 dwelling units: $50
• Multi-family: incremental per unit

Commercial installations are charged based on heating capacity:

• Minimum fee: $75 for systems up to 100,000 BTUs
• Additional: $0.20 per 1,000 BTUs above the 100,000 threshold

Manchester requires permit applications at least 30 days before construction. In pre-1978 buildings, a Lead-Safe Certification is required before a Certificate of Occupancy will be issued for new dwelling units.

Nashua Mechanical Permits

Nashua's Building Safety Department processes mechanical permits with a two-part fee structure:

• Base application and review fee: $50
• Equipment-specific surcharges:
  • Furnace or boiler: $45 each
  • Ductless split unit: $40 each
  • AC condenser: $20 each

Gas piping requires a separate permit with a delivery system fee calculated at $0.30 per 1,000 BTUs.

Ductless mini-split systems that do not use gas require an electrical permit, not a mechanical permit — a distinction that confuses contractors bidding on heat pump installations.

Commercial submittals in Nashua require both a physical paper set and an electronic plan set sent to the Building Safety Department's email.

Permits in Unincorporated Towns

Not every town in New Hampshire has a local code enforcement officer. In unincorporated areas or towns without a building department, the permit authority shifts to the State Fire Marshal's Office.

File a State Building/Mechanical Permit Application through the MyGov portal. The fee is calculated at 1.2% of the first $100,000 of contracted construction cost. The State Fire Marshal's inspectors handle the rough-in and final inspections that would otherwise fall to a local building official.

Planning for Municipal Variation

Every municipality sets its own fee schedule, inspection timelines, and local code amendments. The permit process in Concord looks different from Manchester, which looks different from a small town in the North Country.

Before your first job in a new municipality, call the local building department and ask three questions: what is the permit application process, what is the fee schedule, and what is the typical inspection turnaround time. Building these relationships early prevents delays once projects are underway.

The New Hampshire HVAC License Guide includes permit fee breakdowns for Manchester and Nashua, the State Fire Marshal permit path for unincorporated areas, and a pre-permit checklist that works across municipalities.

See more New Hampshire guides →