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Direct spark ignition controls are essential for reliable furnace operation, improving efficiency and safe startup. This guide highlights five compatible options, clarifying who each is best for and why. Ideal buyers include homeowners upgrading aging ignition boards, technicians seeking straightforward replacements, and facilities managers aiming for diagnostic clarity. Compare each model’s fit, timing, and safety features to choose the right control for your system needs. The following table summarizes key details to help you quickly decide which ignition control to consider.
| Product | Best For | Key Benefit | Limitations |
|---|---|---|---|
| BGN891-1C Ignition Control Module | Pulse furnaces and older Lennox models | Direct replacement with familiar form | Compatibility relies on model match |
| 35-705501-001 Ignition Controls Board | Fenwal HVAC systems | Direct spark ignition with 120V | Check system compatibility with 40LX30 |
| 780-845 Ignition, SP745/SP845 | Robertshaw systems with SP745 family | Diagnostic LED and lockout features | Best with compatible Robertshaw ICU kits |
| Direct Spark Ignition Control, 120V | Fenwal 35-703920-009 applications | 0 sec prepurge configuration | Limited data; verify compatibility |
| Robertshaw DS 845 780-502 | Robertshaw replacement users | Direct Spark with DS 845 family | Brand-specific considerations |
BGN891-1C Ignition Control Module
Direct Replacement for Lennox and Pulse Furnaces. Best for technicians updating legacy Lennox units or similar models with matching circuitry.
35-705501-001 Ignition Controls Board
Best for Fenwal HVAC systems needing a 120V direct spark ignition. Choose this if your unit is a Fenwal 40LX30 style board and you require a direct electrical match.
780-845 Ignition With Diagnostics
Direct replacement for Robertshaw SP745 systems with 780-002 lockout kits. Best for technicians updating Robertshaw ICU configurations. Numerous safeguards include 90 seconds of spark, a 6-minute purge, and a one-hour lockout after repeated failures. It also adds a diagnostic LED to simplify fault identification. A potential limitation is alignment with older or differently wired ICU setups; verify circuit compatibility before install.
Direct Spark Ignition Control, 120V
This model is listed for Fenwal 35-703920-009 applications with 120V direct spark ignition and 0-second prepurge settings. Best for Fenwal-compatible units requiring a straightforward 120V spark ignition. Limitations include limited publicly available data on exact model fit for non-Fenwal units; confirm electrical and flame-sensing compatibility with your furnace.
Robertshaw Direct Spark Ignition DS 845 780-502
Robertshaw DS 845 780-502 is designed for Robertshaw replacement contexts, with DS 845 family compatibility. Best for Robertshaw users who need a direct Spark ignition with diagnostic capabilities. Consider brand-specific installation requirements and ensure the DS 845 family interfaces correctly with your system’s control logic and safety circuits.
Buying Guide
What should you verify before purchasing a direct spark ignition control?
- System compatibility: Confirm model numbers, voltage (120V is common), and flame-sensing method match your furnace.
- Electrical wiring and harness: Check that the control’s connectors align with your control board and harness adapters if needed.
- Diagnostics features: A built-in diagnostic LED or fault codes can speed up service and reduce guesswork.
- Lockout behavior: Understand how long the lockout lasts and how the system retries to restart after a failed ignition.
- Installation constraints: Some units require direct replacement or specific ICU kits for proper integration.
How to Decide Between Models
- Best for Lennox or Pulse Furnaces: BGN891-1C is a direct replacement with familiar form, aiding quick swaps.
- Better for Fenwal Systems: The 35-705501-001 and the Direct Spark Ignition Control for Fenwal 35-703920-009 suit Fenwal applications.
- Best with Diagnostic Capability: 780-845 and DS 845 780-502 offer clear LED indicators to diagnose faults quickly.
- Choose this if you need a straightforward 120V spark: The 120V Fenwal option is simple and often widely compatible with Fenwal setups.
Frequently Asked Questions
- What is a direct spark ignition control?
It is a control module that directly initiates a flame by sending a spark to the ignition electrode during every heat call. - Do these modules require professional installation?
For safety and proper function, installation is typically performed by HVAC professionals familiar with furnace ignition systems. - Can I mix brands in the same furnace?
Avoid mixing brands unless specifically approved by the furnace manufacturer and the control’s documentation. - What is a flame sensor diagnostic LED?
A built-in LED indicates normal operation, lockout, or external issues, helping technicians diagnose quickly. - How do I know which model fits my furnace?
Compare your furnace’s model number, voltage, and ignition type with the product’s listed compatibility and wiring requirements. - Is a lockout period common?
Yes. A lockout period helps prevent repeated ignition attempts when flame cannot be established, protecting the system.