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ANSI Z21.87-2007 / CSA 4.6-2007: Automatic Gas Ignition Systems and Components
Technical insights into the harmonized North American standard for ignition controls in gas-fired appliances
The ANSI Z21.87-2007 / CSA 4.6-2007 standard establishes the safety and performance requirements for automatic gas ignition systems and components used in residential, commercial, and industrial gas-burning appliances. Developed under the American National Standards Institute (ANSI) and the Canadian Standards Association (CSA), this harmonized standard ensures that ignition controls meet stringent criteria for reliability, durability, and safety across North America.
Scope and Applicability
This standard applies to automatic ignition systems that initiate and sustain combustion in gas-fired appliances operating on natural gas, propane, or liquefied petroleum gases. It covers systems that automatically light the main burner or a pilot burner and includes all associated components such as ignition control modules, igniters (spark, hot surface, or pilot), flame sensors, interconnecting wiring, and mounting provisions.
The standard does not apply to manually lit systems, appliances intended for use with non-flammable gases, or ignition systems integrated into cooking appliances covered by other specific standards (e.g., ranges and ovens). It is referenced in major North American building codes including the International Fuel Gas Code (IFGC) and the National Fuel Gas Code (NFPA 54).
Technical Requirements
Classification of Ignition Systems
ANSI Z21.87-2007 categorizes automatic ignition systems according to their operating principle. The classification helps designers select appropriate components and determine applicable test criteria. Table 1 summarizes the recognized types.
| Ignition System Type | Operation Principle | Typical Applications |
|---|---|---|
| Direct Spark Ignition (DSI) | High-voltage spark ignites gas directly at the main burner port | Warm-air furnaces, gas boilers, commercial cooking equipment |
| Hot Surface Ignition (HSI) | Silicon carbide or silicon nitride element reaches incandescent temperature to ignite gas | Residential and light commercial furnaces, gas ranges, dryers |
| Intermittent Pilot (IP) | Spark-ignited pilot burner remains lit during the entire heating cycle | Water heaters, boilers, pool heaters |
| Interrupted Pilot (ID) | Pilot burner is ignited before main burner but is extinguished after main burner ignition | Commercial boilers, direct-fired make-up air units |
Performance Requirements
The standard defines minimum performance limits for ignition trials, flame detection, and safety lockout. Specific values depend on the system type and appliance category, but typical parameters are listed in Table 2. All tests are conducted under defined supply voltages, gas pressures, and ambient conditions as specified in the standard.
| Parameter | Requirement | Test Condition |
|---|---|---|
| Ignition trial period | ≤ 10 seconds (DSI/HSI) | At rated gas supply and voltage |
| Safety lockout time | ≤ 10 seconds after loss of flame | Flame failure during steady state operation |
| Flame signal strength | ≥ 1.0 µA DC (rectification sensing) | Nominal gas rate, ambient conditions |
| Voltage tolerance | 85 % – 110 % of rated voltage | During all modes of operation |
| Cycle endurance | ≥ 1,000,000 cycles (design life) | Accelerated life test at maximum rate |
Additional requirements cover electrical insulation (creepage and clearance), dielectric strength, and resistance to humidity and vibration. Component markings must include manufacturer identity, model number, electrical ratings, and the certification body’s mark.
Implementation and Design Considerations
Design Tip: When using hot surface igniters, consider inrush current and element aging. Incorporate pre- and post-purge sequences as required by the appliance standard to prevent delayed ignition.
Safety Warning: Flame sense circuits must be designed to distinguish reliably between a live flame and leakage currents. Always verify circuit behavior under high humidity and in the presence of soot or contaminants.
Certification Benefit: Products listed to ANSI Z21.87-2007 / CSA 4.6-2007 are accepted by building officials and gas utilities across the United States and Canada, streamlining market access.
Risk of Non-Compliance: Using ignition controls not tested to this standard can void the appliance certification, create liability for fire or explosion, and violate local fuel-gas codes.
Compliance and Certification
To demonstrate compliance, manufacturers must submit their ignition system or component to an accredited Nationally Recognized Testing Laboratory (NRTL) such as UL, CSA, or Intertek. The evaluation includes:
- Construction review (materials, spacing, wiring)
- Performance testing (ignition timing, lockout, flame current)
- Accelerated endurance and environmental tests
- Label and marking verification
Certified products bear the certificate mark of the testing laboratory and the designator “ANSI Z21.87” or “CSA 4.6”. Manufacturers should note that the 2007 edition may have been updated; it is essential to refer to the latest edition (e.g., ANSI Z21.87-2020) for current requirements. The standard is maintained by the Z21/83 Committee under continuous maintenance procedures.
Q: What types of appliances fall under the scope of this standard?
A: Automatic ignition systems for virtually all gas-fired appliances except those using manually lit pilots, including furnaces, boilers, water heaters, unit heaters, and commercial cooking equipment.
A: Automatic ignition systems for virtually all gas-fired appliances except those using manually lit pilots, including furnaces, boilers, water heaters, unit heaters, and commercial cooking equipment.
Q: What is the relationship between ANSI Z21.87-2007 and CSA 4.6-2007?
A: They are identical dual national standards. A product certified to either designation simultaneously meets both the US and Canadian requirements, simplifying cross-border trade.
A: They are identical dual national standards. A product certified to either designation simultaneously meets both the US and Canadian requirements, simplifying cross-border trade.
Q: Are hot surface and spark ignition systems treated differently?
A: Yes. The standard classifies each ignition type and applies distinct test procedures, particularly for measurement of ignition energy, lockout timing, and flame signal rectification.
A: Yes. The standard classifies each ignition type and applies distinct test procedures, particularly for measurement of ignition energy, lockout timing, and flame signal rectification.
Q: Where can I access the full text of ANSI Z21.87-2007?
A: The complete standard is available from ANSI, CSA, and third-party standards distributors. Always verify you are using the current edition, as newer versions include expanded requirements for electronic controls.
A: The complete standard is available from ANSI, CSA, and third-party standards distributors. Always verify you are using the current edition, as newer versions include expanded requirements for electronic controls.
Published: 2026. This technical summary is for informational purposes only. Always consult the official standard for enforceable requirements.