Lennox 21J99 – 105802-02 Direct Spark Ignition Control Board is an OEM replacement module engineered to provide reliable ignition control for Lennox unit heaters rated from 30,000 to 105,000 BTUH. This board manages the complete ignition sequence, including spark generation, flame proving, system safety monitoring, and protective lockout functions. Its updated circuitry ensures consistent burner performance and dependable operation in both residential and light commercial environments.

Designed for seamless compatibility with select Lennox unit heater models, this control board restores proper ignition performance when dealing with issues such as failure to light, intermittent heating, or flame sensing errors. Its plug-and-play design allows for fast replacement and improved system reliability.

 

Key Features:

• OEM Lennox 105802-02 ignition control board for unit heaters
• Supports unit heater capacities from 30K to 105K BTUH
• Controls spark ignition, flame sensing, and system safety
• Updated electronic design enhances long-term reliability
• Designed for fast, accurate installation
• Ideal for fixing ignition failures or inconsistent heating operation

 

Specifications:

Manufacturer: Lennox
Part Number: 21J99
Replaces: 105802-02
Application: Direct spark ignition control for unit heaters
Heating Capacity Range: 30,000 to 105,000 BTUH
Ignition Type: Direct spark ignition
Flame Sensing: Flame rectification
Control Functions: Ignition sequencing, safety lockout, system monitoring
Voltage: 24 VAC control
Operating Temperature: Standard HVAC control range
Compatibility: Select Lennox unit heater models (DSI-equipped units)
Mounting Type: OEM board mounting pattern
Product Type: Ignition control replacement module