Confirm which boilers and combustion systems the project treats as within NFPA 85, then trace each unit’s fuel train, burner management system, combustion air, flue, and interlocks through every discipline. AI can flag conflicts; the engineer of record and the authority having jurisdiction decide compliance.
What does NFPA 85 cover?
NFPA 85 is the Boiler and Combustion Systems Hazards Code. NFPA describes it as contributing to operating safety and preventing explosions and implosions in boilers above a stated fuel input, pulverized fuel systems, and heat recovery steam generators. Read the applicability limits in the edition the authority adopts rather than relying on a summary.
NFPA’s official NFPA 85 page identifies the 2023 edition as current when checked on October 5, 2026. Confirm the edition, local amendments, and project scope that actually govern the work. The publisher’s newest edition does not establish local adoption.
Smaller boilers and appliances are generally addressed by other documents, such as the NFPA 54 fuel gas guide for gas piping and appliances and the IMC guide for mechanical systems. Record the basis the engineer of record states for each unit before comparing controls.
Start from the boiler and combustion equipment list
Collect the boiler or HRSG schedule, the vendor general arrangement drawings, the fuel train and gas or oil piping diagrams, the burner management system and combustion control narratives, the controls and interlock diagrams, the mechanical plans and sections for the boiler room, the flue and stack drawings, the combustion air louvers and ductwork, the electrical drawings for the boiler controls, and the specifications.
Record each unit’s fuel, firing arrangement, and whether it shares a stack, fuel supply, or control panel with another unit. Shared systems are where documents most often disagree.
Follow each unit from fuel to flue
| Review question | Sources to compare | Decision to record |
|---|---|---|
| Equipment and basis | Boiler schedule, vendor drawings, design narrative | Confirm each unit, its fuel, and the stated code basis agree across sources. |
| Fuel train | Fuel piping diagrams, vendor data, specifications | Match valves, regulators, and vent lines shown by the vendor with the building piping. |
| Burner management | Control narrative, interlock diagrams, electrical drawings | Check that the interlocks and safety shutoffs in the narrative appear on the control and wiring drawings. |
| Combustion air | Mechanical plans, louver schedule, elevations | Identify combustion air openings or ducts drawn by one discipline and missing on another. |
| Flue and stack | Mechanical plans, sections, roof plan, vendor data | Trace each flue to its stack and termination and compare sizes and tags with the vendor drawings. |
| Room and access | Architectural plans, sections, vendor clearances | Compare the drawn room and doors with the vendor’s stated service and removal space. |
Carry gas service into the NFPA 54 fuel gas guide, controls into the HVAC controls specifications guide, and the room into the mechanical drawing checklist.
Example: an interlock in the narrative only
Hypothetical example. The combustion control narrative says the burner is interlocked with the combustion air damper and the boiler room exhaust fan. The control wiring diagram shows the damper interlock but not the fan, and the fan schedule lists the fan on a separate building automation point.
The combustion control narrative requires an interlock between the burner and the boiler room exhaust fan, but the control wiring diagram and fan schedule do not show it. Please confirm the interlock and revise the drawings or narrative to match.
The engineer of record and the boiler vendor resolve the interlock. Whether the controls meet the adopted code is the engineer’s and authority’s decision.
Review a boiler package with Groundbook
Upload the current project PDFs and relevant specifications to Groundbook. Identify the governing issues and add the applicable NFPA 85 reference from a copy you are licensed to use, where the license permits uploading it. State the edition, amendments, review area, and known exclusions in your instructions.
Compare the boiler schedule, vendor drawings, fuel train diagrams, burner management and combustion control narratives, interlock and wiring diagrams, boiler room plans and sections, flue and stack drawings, combustion air drawings, and specifications. Flag equipment, fuel, controls, air, and flue information that differ between sources. Use the supplied NFPA 85 edition where applicable and cite both sources.
Groundbook links each potential finding to the sheets behind it. It does not decide whether a unit falls within the code’s applicability limits.
Document review does not size fuel trains, flues, or combustion air, verify burner management logic, or approve the installation. Those decisions remain with the engineer of record, the boiler vendor, and the authority having jurisdiction.