1 Scope
NOTE This standard covers the selection, fabrication, connection, controls integration, and commissioning of gas-fired radiant and infrared heaters for commercial and industrial spaces. (1.1)
NOTE Two heater families are covered, and they are governed by distinct product safety standards that are not interchangeable. (1.2)
NOTE High-intensity luminous heaters radiate from a glowing ceramic or perforated metal surface at the burner face, are typically unvented, and serve open or partially open spaces such as dock doors, automotive service bays, and spot-heating positions. (1.2.1)
NOTE Low-intensity radiant tube heaters radiate from a heated steel tube driven by a remote burner, are typically vented, and serve enclosed warehouse and manufacturing floors. (1.2.2)
NOTE Heaters covered here deliver heat primarily by infrared radiation to surfaces and occupants rather than by warming and circulating room air. (1.3)
NOTE The 80% case for an industrial project is a vented low-intensity straight-tube or U-tube heater, 100,000 to 150,000 BTU/hr, natural gas, two-stage or modulating, mounted at 16 to 24 ft above finished floor in a warehouse or manufacturing bay. (1.4)
NOTE The following are not within this scope: (1.5)
- Hydronic and electric cabinet or propeller unit heaters, addressed in Unit Heaters.
- Baseboard, fin-tube, cabinet convectors, and radiant ceiling or wall panels, addressed in Terminal Heating Units.
- Natural gas and propane piping, regulators, and meter sets upstream of the heater gas connection, addressed in Natural Gas Piping.
- Supply and exhaust fans serving combustion-air ventilation, addressed in Hvac Fans.
- Electric resistance quartz and ceramic infrared heaters, outdoor decorative patio heaters, and industrial process ovens, dryers, and curing systems.
1.6 Heater type, fuel, capacity, configuration, mounting, controls, and combustion-air arrangement shall be selected as required to meet the heating load and the conditions of the served space.
● Low-intensity radiant tube (vented, enclosed spaces)
○ High-intensity luminous (unvented, open or spot heating)
● Natural gas
○ Propane (LP)
2 Referenced Standards
2.1 Equipment, materials, and installation shall comply with the latest adopted edition of each of the following unless a specific edition is cited.
2.2 Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
NOTE The adopted edition of each code is the one enforced by the authority having jurisdiction; cited editions reflect a common current baseline. (2.3)
| Standard |
Title |
| ANSI Z83.19 / CSA 2.35-2017 |
Gas-Fired High-Intensity Infrared Heaters |
| ANSI Z83.20 / CSA 2.34-2017 |
Gas-Fired Low-Intensity Infrared Heaters |
| ANSI/AHRI 1330-2024 (SI) |
Performance Rating for Radiant Output of Gas-Fired Infrared Heaters |
| NFPA 54 / ANSI Z223.1-2021 |
National Fuel Gas Code |
| NFPA 1-2021 |
Fire Code |
| ASHRAE 90.1-2022 |
Energy Standard for Sites and Buildings Except Low-Rise Residential |
| IBC-2021 |
International Building Code (Chapter 14; structural support) |
| IMC-2021 |
International Mechanical Code (Chapter 10; appliance installation) |
| NFPA 70 / NEC-2023 |
National Electrical Code (Article 422, Appliances) |
| CSA/ANSI Z83.26 / CSA 2.37-2020 (R2025) |
Gas-Fired Outdoor Infrared Patio Heaters (only if outdoor units in scope) |
3 Submittals
3.1 The Contractor shall submit the following action submittals for review before fabrication or delivery:
- Product data for each heater type, including input capacity, fuel type, tube geometry and length, reflector material, ignition type, and electrical characteristics.
- Manufacturer certification of listing to ANSI Z83.19 (high-intensity) or ANSI Z83.20 (low-intensity) as applicable, including the listing label clearances to combustibles.
- Radiant performance data per ANSI/AHRI 1330-2024, reporting the Radiant Emission Value (REV) and net radiant efficiency for each model.
- A heater layout plan showing position, mounting height, tilt angle, coverage pattern, clearances to combustibles, and clearances to obstructions (racking, cranes, mezzanines).
- Gas connection schematic showing required inlet pressure, manifold pressure, and connection size for each heater.
- Combustion-air and venting design, including vent material, vent routing to exterior, and termination location for vented units; ventilation rate calculation for unvented units.
- Wiring diagrams for ignition, controls, staging or modulation, and any building automation system interface.
- Structural support and hanger details, including connection to roof structure and, where required, seismic bracing and vibration-isolation provisions.
☑ Product data (each heater type)
☑ Z83.19 / Z83.20 listing certification
☑ AHRI 1330 REV and radiant efficiency data
☑ Heater layout plan with clearances
☑ Gas connection schematic
☐ Combustion-air and venting design
☑ Control and wiring diagrams
☑ Structural support and bracing details
3.2 The Contractor shall submit the following closeout submittals before substantial completion:
- Installation, operation, and maintenance (IOM) manuals for each heater model.
- Commissioning report documenting gas pressure verification, ignition checks, staging or modulation verification, and combustion or flue-spillage checks.
- Manufacturer warranty documentation for heat exchangers, burners, and controls.
- Record drawings reflecting as-installed heater positions, gas routing, and vent terminations.
☑ IOM manuals
☑ Commissioning report
☑ Warranty documentation
☑ Record drawings
3.3 The Contractor shall submit the following informational submittals:
- Manufacturer field service or startup report where factory commissioning is specified.
- Operator training records, including attendance and topics covered.
☑ Field startup report
☑ Operator training records
4 Quality Assurance
4.1 High-intensity luminous heaters shall be listed and labeled to ANSI Z83.19 / CSA 2.35.
4.2 Low-intensity radiant tube heaters shall be listed and labeled to ANSI Z83.20 / CSA 2.34.
4.3 The specifying engineer shall confirm whether the application is open or enclosed before selecting between high-intensity and low-intensity heaters.
NOTE The two product standards are not interchangeable; a contractor substitution across families changes the venting, ventilation, and clearance basis. (4.4)
4.5 Radiant performance shall be rated in accordance with ANSI/AHRI 1330-2024, and submitted data shall report the Radiant Emission Value (REV).
NOTE The 2024 edition of AHRI 1330 introduced the Radiant Emission Value as a directly comparable measure of usable radiant output, replacing older radiant efficiency fractions; specifying REV on submittals prevents substitution of a heater that meets the BTU input rating but delivers materially less radiant heat to occupant level. (4.6)
4.7 Each heater shall be the product of a single manufacturer for a given heater family on the project, to maintain consistency of parts, controls, and service support.
4.8 Manufacturer field service representatives performing startup shall be factory-trained and authorized for the supplied equipment.
5 Environmental and Service Conditions
5.1 Heaters shall be selected for the served space's ceiling height, infiltration, insulation level, door-cycle exposure, and occupant heat gain, not by a rule-of-thumb BTU per square foot value.
NOTE High-bay and dock-door-heavy facilities have infiltration and stratification behavior that rule-of-thumb area loads do not capture; a building heat-loss calculation is the basis of capacity and heater count, and skipping it produces undersized or oversized systems and uneven coverage. (5.2)
5.3 Tube material shall be selected for the corrosivity of the served environment.
NOTE Aluminized steel tube is the standard selection for dry, non-corrosive interior environments. (5.3.1)
5.3.2 Stainless steel tube shall be specified for combustion chambers and for installations exposed to washdown, salt, or chemical atmospheres.
NOTE Aluminized steel corrodes prematurely in washdown, salt, or chemical environments; stainless steel is required in those conditions. (5.3.3)
NOTE Titanium combustion-chamber tube may be specified for the most aggressive corrosive service where extended tube life justifies the cost. (5.3.4)
● Aluminized steel (standard dry interior)
○ Stainless steel combustion chamber
○ Stainless steel full length (corrosive/washdown)
○ Titanium combustion chamber (aggressive service)
5.4 In Seismic Design Category C and above, heater supports and bracing shall be designed in accordance with IBC Table 1613 seismic provisions.
5.5 Where heaters are suspended from a vibrating structure, vibration-isolation hangers shall be provided in accordance with NFPA 54.
● Not required (SDC A or B)
○ Required (SDC C and above)
6.1 Each heater's input capacity shall be selected from the heat-loss calculation for the zone it serves.
NOTE Input capacity for a typical industrial low-intensity tube heater falls between 80,000 and 150,000 BTU/hr; the full covered range for the equipment family is 20,000 to 250,000 BTU/hr per unit. (6.2)
20000250000
Default: 125000 BTU/hr
6.3 High-intensity luminous heaters shall have a net radiant efficiency of not less than 55%.
6.4 Low-intensity radiant tube heaters shall have a net radiant efficiency of not less than 45%.
NOTE Net radiant efficiency is the fraction of fuel input emitted as usable infrared radiation toward the occupied zone; the minimum thresholds reflect the AHRI 1330 / NECB basis and are the floor below which a heater is not considered an efficient radiant emitter. (6.5)
6.6 Steady-state thermal efficiency of the heater shall be not less than the minimum required by ASHRAE 90.1 where the project pursues energy code compliance.
NOTE Steady-state thermal efficiency for tube heaters typically ranges from 77% to 93% on a higher-heating-value basis; a standard tube heater is approximately 80% to 85%. (6.7)
7 Heater Construction and Configuration
7.1 Low-intensity heater tube geometry shall be selected for the coverage pattern and the available run length of the zone.
NOTE Straight single-pass tube provides a linear coverage pattern along the run and suits long aisles and perimeter runs. (7.1.1)
NOTE U-tube geometry folds the run to fit a shorter footprint while retaining tube length, and suits bays where a straight run will not fit. (7.1.2)
NOTE Multi-burner continuous-tube systems provide a single continuous radiating run served by multiple burners for very long coverage, and suit large open floors. (7.1.3)
○ Straight single-pass
● U-tube
○ Multi-burner continuous tube
7.2 Tube length shall be coordinated with mounting height per the manufacturer's layout guide so that the coverage pattern is uniform over the occupied zone.
NOTE A long tube hung at a low mounting height concentrates heat unevenly along the run; the tube-length-to-mounting-height ratio shall be evaluated against the manufacturer's layout guide rather than chosen by tube length alone. (7.3)
NOTE The 80% case is a 40 ft straight or U-tube heater; the practical range is 20 to 80 ft for single-burner straight tubes, with U-tubes giving an equivalent effective length of roughly 30 to 60 ft. (7.4)
7.5 Tube diameter shall be 4 in. for standard industrial capacity ranges and may be 3 in. for lower-capacity units.
● 4 in. (standard industrial)
○ 3 in. (lower capacity)
7.6 Reflectors shall be provided over the full radiating length to direct radiant output downward toward the occupied zone.
NOTE Reflector finish shall be specified for the application; polished aluminum and polished stainless steel are the common finishes. (7.6.1)
NOTE A higher-reflectance, durable finish increases the fraction of radiant output directed to the floor and resists tarnishing in dusty or humid spaces. (7.6.2)
● Polished aluminum
○ Polished stainless steel
7.7 Reflector assemblies shall include the manufacturer's expansion provision to accommodate thermal movement of the tube.
7.8 Reflector expansion joints and burner-end baffles shall be verified against the IOM before energizing.
NOTE Omitting the reflector expansion joint, or installing the burner-end baffle in the wrong tube segment, are common installation errors that cause tube burn-through or poor heat distribution. (7.9)
7.10 The burner ignition system shall be direct spark ignition or hot surface ignition as scheduled.
● Direct spark ignition
○ Hot surface ignition
8 Mounting and Clearances
NOTE Mounting height for low-intensity tube heaters typically ranges from 10 to 35 ft, and for high-intensity luminous heaters from 8 to 20 ft; the 80% warehouse case mounts low-intensity heaters at 16 to 24 ft above finished floor. (8.2)
● Ceiling-mount (horizontal)
○ Angle-mount (tilted)
○ Wall-mount
8.3 Clearances to combustibles shall comply with the listing label and the manufacturer's IOM for the specific model and mounting configuration.
NOTE Listed clearances for tube heaters are typically on the order of 48 to 84 in. above and 36 in. to the sides, but the listing label and IOM are the governing values for the supplied model and shall always be used in place of any generalized figure. (8.4)
8.5 The minimum mounting height and the maximum permitted combustible stacking height below each heater shall be shown on the layout plan and posted at the heaters.
NOTE NFPA 54 and NFPA 1 require posted signage for combustible clearances below radiant heaters; a specification that omits the minimum mounting height and maximum stacking height generates RFIs and fails code inspection. (8.6)
8.7 The heater layout shall account for line-of-sight obstructions such as high racking, overhead cranes, and mezzanines so that no occupied area is shadowed.
NOTE Radiant heat travels in straight lines, so tall racking can shadow lower zones; where obstructions block coverage, supplemental lower-mount or spot heaters shall be added to the layout rather than relying on the overhead heaters alone. (8.8)
9 Gas, Combustion Air, and Venting
9.1 Each heater's required gas inlet pressure shall be verified against the available supply pressure at the heater connection.
NOTE Natural gas heaters typically require 6 to 14 in. W.C. inlet pressure and propane heaters typically require 11 to 14 in. W.C.; these requirements shall be coordinated with the building regulator and meter set, because a low-pressure distribution system can fail to deliver the heater's minimum inlet pressure. (9.2)
9.3 Combustion air shall be provided in accordance with NFPA 54, Section 9.3, for the volume of the space and the total connected input.
9.4 The combustion-air source shall be induced-draft, power-vented, or natural-draft as scheduled, and the flue shall be routed to the exterior.
● Induced-draft (vented)
○ Power-vented (vented)
○ Natural-draft (vented)
○ Unvented (high-intensity)
9.5 Vented heaters shall be vented as a Category I or Category II appliance per NFPA 54, Chapter 12, using Type B vent or single-wall metallic vent as listed for the model.
9.6 Where two or more tube heaters share a common vent, their controls shall be interlocked so the off-cycle unit cannot be back-fed by exhaust from the operating unit.
9.7 Common vents shared by two or more tube heaters shall be used only where the controls are interlocked so the off-cycle unit cannot receive back-fed exhaust from the operating unit.
9.8 Where interlocking common-vent controls is not feasible, individual vents shall be provided for each heater.
NOTE Common-venting tube heaters without interlocked controls drives exhaust from the operating unit down the flue of the off-cycle unit, causing premature heat exchanger failure and a carbon monoxide hazard. (9.9)
9.10 Unvented high-intensity heaters shall be installed only where mechanical ventilation provides at least 4 ft³/min per 1,000 BTU/hr of connected input, in accordance with NFPA 54.
9.11 Unvented luminous heaters shall not be specified in spaces with inadequate ventilation or with combustible storage directly below.
NOTE Unvented luminous heaters discharge combustion products into the space; specifying them where ventilation is inadequate or combustible storage is directly below creates both a fire code violation and a carbon monoxide hazard. (9.12)
48
Default: 4 CFM per 1000 BTU/hr
10 Electrical
10.1 Electrical connection shall comply with NFPA 70 (NEC) Article 422 for appliances.
10.2 Heaters shall be supplied at 120V, single-phase, 60 Hz unless otherwise scheduled, with ignition and control current draw typically between 2 and 8 A.
● 120V / 1Φ / 60 Hz
○ 24V control (transformer-supplied)
10.3 A disconnecting means shall be provided within sight of each heater, or lockable at the heater, in accordance with NEC Article 422.31.
11 Controls
11.1 The heater control strategy shall be selected for the zoning and turndown the space requires.
NOTE A single-stage thermostat zone is the simplest control and suits small or uniformly loaded spaces. (11.1.1)
NOTE Two-stage firing (typically 65% and 100%) reduces cycling and improves comfort in larger zones. (11.1.2)
NOTE Modulating control (typically 40% to 100% turndown) gives the smoothest output and the best part-load efficiency for large or variable loads. (11.1.3)
○ Single-stage thermostat
● Two-stage (65% / 100%)
○ Modulating (40-100%)
11.2 Where modulating or staged heaters are integrated with a building automation system, the interface protocol shall be confirmed with the BAS engineer before procurement.
NOTE Specifying modulating or staged controls without confirming the integration protocol with the building automation system results in standalone thermostats that cannot participate in demand-controlled heating; the protocol shall be coordinated with
Building Automation System before the heaters are released.
(11.3) ● Standalone thermostat (no BAS)
○ 0-10V analog
○ BACnet MS/TP
○ BACnet/IP
12 Installation
12.1 Heaters shall be installed in accordance with the manufacturer's IOM, the listing label, NFPA 54, and the International Mechanical Code.
12.2 Heater hangers shall be supported from the building structure as detailed, and not from the bottom chords of open-web steel joists alone.
12.3 Hanger loads shall connect to joist panel points, bridging, or approved supplemental structural support, and shall not be applied to the joist bottom chord between panel points.
12.4 Hanger attachment locations shall be coordinated with the structural engineer.
NOTE Warehouse roofs are commonly open-web steel joists; applying hanger loads to the bottom chord between panel points can overstress the chord. (12.5)
12.6 Gas connections to each heater shall be made with a listed flexible connector and an accessible manual shutoff valve at the heater.
12.7 Final gas piping to the heater shall connect to the building gas distribution as covered by Natural Gas Piping; the connection point, regulator, and manifold pressure are coordinated there. 12.8 Vent terminations shall be located in accordance with NFPA 54 clearance-to-opening requirements and shall be coordinated with combustion-air intakes and supply-air openings served by Hvac Fans. 12.9 Reflector segments, expansion joints, and burner-end baffles shall be installed in the positions and segments designated in the IOM, and verified before energizing.
13 Testing and Commissioning
13.1 Each heater shall be commissioned in accordance with the manufacturer's startup procedure.
13.2 Gas inlet pressure and manifold pressure shall be measured at each heater and confirmed to be within the manufacturer's required range under firing conditions.
13.3 Ignition shall be verified for reliable light-off, and staging or modulation shall be verified to track the control signal across the firing range.
13.4 Vented heaters shall be checked for proper draft and the absence of flue-gas spillage at the draft hood or barometric relief.
13.5 Unvented heaters shall be commissioned only after the required ventilation rate is confirmed to be operating.
13.6 A carbon monoxide spot check shall be performed in the occupied zone of spaces served by unvented heaters.
13.7 Commissioning results shall be recorded in the commissioning report submitted at closeout.
14 Delivery, Storage, and Handling
14.1 Heaters, tubes, reflectors, and controls shall be delivered in the manufacturer's original packaging with listing labels intact.
14.2 Tubes and reflectors shall be stored off the ground and protected from moisture, dust, and physical damage until installation.
14.3 Burner and control assemblies shall be kept dry and protected from construction debris until the heaters are energized.
15 Warranty
15.1 The manufacturer shall warrant heat exchangers, tubes, and burners against defects in materials and workmanship for not less than the period scheduled for the project.
15.2 The manufacturer shall warrant burner controls and ignition components for not less than the period scheduled for the project.
16 Spare Parts
16.1 The Contractor shall furnish the spare parts scheduled below, in the manufacturer's original packaging and labeled for the heater model they serve.
- One spare ignition assembly (spark electrode or hot surface igniter) per heater model.
- One spare gas valve per heater model.
- One spare flame-sensing or safety control per heater model.
☑ Ignition assembly (per model)
☐ Gas valve (per model)
☑ Flame-sense / safety control (per model)