1.2 Heating Classifications, Groups & Scopes

Heating Classifications, Groups & Scopes

Core Rule (G.S. 87-21(a) and (b)(1); 21 NCAC 50 .0501): North Carolina divides heating licenses into three technical groups (H1, H2, H3) and two scope tiers — Class I covering all plumbing, heating, and fire sprinkler systems for all structures, and Class II covering plumbing and heating systems in single-family detached residential dwellings only. The single statutory divider between forced-air groups is mechanical refrigeration capacity of 15 tons. The statute sets no Btu/h heating threshold; any number expressed in Btu/h of heat output is a distractor.

The Heating License Group Classifications

The scopes are fixed by statute in G.S. 87-21(a)(2), (3) and (4), refined by 21 NCAC 50 .0501, .0507, .0508 and .0511, and summarized in the Board's published License Definitions — Contractor document:

1. Heating Group 1 (H1) — Hydronics, Steam & Boilers

• System Types: Low-pressure boilers (steam not exceeding 15 psig, hot water not exceeding 160 psig or 250°F), high-pressure boilers, hydronic heating loops, radiant floor hydronics, baseboard convectors, steam piping, condensate return systems, expansion tanks, and boiler water treatment systems.
• Class I (H1-I): Unlimited hydronic and steam heating installations in any commercial, industrial, institutional, or residential structure.
• Class II (H1-II): "Wet" or water-based comfort heating systems installed exclusively in single-family detached dwellings. Class II never extends to duplexes, townhouse rows, apartment buildings, or any commercial occupancy.
• Boiler Rule (21 NCAC 50 .0507): A Heating Group 1 license is required for the installation or replacement of a boiler in a Group 1 system, irrespective of who installs the surrounding piping.
• Fuel Scope: Authorized to install, alter, and service fuel gas (natural gas and LP gas) and oil piping systems connected directly to Group 1 heating equipment.

2. Heating Group 2 (H2) — Large Commercial Forced Air & Air Conditioning

• Statutory Definition (G.S. 87-21(a)(3)): "An integral system for heating or cooling a building consisting of an assemblage of interacting components producing conditioned air to raise or lower the temperature, and having a mechanical refrigeration capacity in excess of fifteen tons, and which circulates air."
• Single-Family Carve-Out: The same subsection states that systems installed in single-family residences are included under Heating Group 3 regardless of size — a 20-ton system in a large custom home is H3 work, not H2 work.
• Aggregation Rule (21 NCAC 50 .0501(a)): Multiple units serving interconnected space and aggregating more than 15 tons are Heating Group 2 systems, whether or not they are separately ducted or separately controlled.
• Equipment Included: Large commercial packaged rooftop units (RTUs), chillers providing chilled water to air handling comfort units, commercial variable refrigerant flow (VRF) comfort systems over 15 tons, built-up central station air handlers, commercial duct distribution systems, ventilation air makeup units, and commercial exhaust systems.
• Scope: Primarily commercial, industrial, and institutional buildings where large-capacity air distribution is required.
• Fuel Scope: Authorized to install and alter fuel gas piping serving Group 2 heating equipment.

3. Heating Group 3 (H3) — Residential & Light Commercial Forced Air

Heating Group 3 is the most common mechanical license in North Carolina and is subdivided into two distinct classes:

• Heating Group 3, Class I (H3-I) — All Structures (≤ 15 Tons):
  • A direct heating or cooling system in which electric heating elements or products of combustion exchange heat with the supply air (directly or through a heat exchanger) using an air distribution system of ducts, having a mechanical refrigeration capacity of 15 tons or less (G.S. 87-21(a)(4)).
  • Valid in commercial retail buildings, offices, restaurants, churches, multi-family apartment buildings, and residences, plus any single-family residence regardless of tonnage.
  • Equipment trigger (21 NCAC 50 .0508): an H3 license is required to install or replace a furnace, air handler, heat pump, package unit, ductwork, or condenser in a Group 3 system; to install a self-contained fireplace unit that uses ducts or a blower to distribute air beyond the immediately adjacent area; and when air conditioning of 15 tons or less is added to an already installed Group 3 heating system.
  • Aggregation trap: five 10-ton rooftop units serving one interconnected commercial space total 50 tons, so under 21 NCAC 50 .0501(a) the job is Heating Group 2 work, not H3-I work — the per-unit size is irrelevant when the space is interconnected.
• Heating Group 3, Class II (H3-II) — Single-Family Detached Only:
  • Forced air heating and comfort air conditioning systems of 15 tons or less installed exclusively in single-family detached residential dwellings (G.S. 87-21(b)(1)).
  • An H3-II licensee cannot work on duplexes, townhouse rows, apartment buildings, commercial buildings, business occupancies, churches, or restaurants, regardless of system tonnage.

Summary Matrix of NC Heating Classifications

Fuel Piping (FP) Licensing Rules & Authorizations

Under 21 NCAC 50 .0511, fuel piping authorization governs natural gas, LP gas, and (in non-residential applications) combustible liquid fuel distribution:

1. Inherent Fuel Piping Scope: The contracting or installation of fuel piping extending from an approved fuel source at or near the premises to a point within the premises requires a Plumbing, Heating Group 1, Heating Group 2, Heating Group 3, or Fuel Piping license — regardless of the nature of the system, equipment, or appliance served. A Class II license does not gain extra reach from this rule: it remains restricted to single-family detached residential dwellings.
2. Standalone Fuel Piping (FP) License: A contractor who holds only the Fuel Piping (FP) license may install fuel gas piping from the source of supply to appliances (including water heaters, ranges, dryers, fireplaces, and gas generators), but is not authorized to install, connect, or service the heating, air conditioning, or boiler equipment itself.
3. LP Gas Tank Interconnection: The high-pressure piping from the LP container to the first-stage regulator is regulated under the jurisdiction of the North Carolina Department of Agriculture & Consumer Services (Standards Division). The mechanical contractor's jurisdiction typically begins at the output of the first/second-stage regulator or building line according to the NC Fuel Gas Code.