Honeywell RM7850A2019 Relay Module Burner Control with Grounding Pin

120V Microprocessor-Based Primary Control for On-Off Burners

The Honeywell RM7850A2019 is a microprocessor-based primary burner control from the RM7800 Series, designed to manage on-off burner systems with gas, oil, or combination fuel. It provides reliable burner sequencing, flame monitoring, and safety shutdown, along with built-in system diagnostics. With modular compatibility, selectable safety interlocks, and support for plug-in flame amplifiers, the RM7850A2019 is ideal for industrial and commercial burner management.

Technical Specifications

• Model: RM7850A2019
• Series: RM7800
• Product Type: Primary Burner Control
• Power Supply: 120V AC (+10%, -15%), 50/60 Hz
• Application: On-Off Burner Control
• Pilot Type: Intermittent
• Flame Establishing Period – Pilot: 4 or 10 seconds
• Flame Establishing Period – Main: Intermittent
• PrePurge: Configured using ST7800A Purge Timer Card
• Interlocks: Selectable
• Delayed Main Valve: No
• Airflow Switch Check: Included
• Mounting: Q7800A or Q7800B Universal Subbase (required)
• Flame Amplifier Compatibility: R7847, R7848, R7849, R7851, R7852, R7861, R7886
• LED Indicators: 5 LEDs for burner sequence and lockout status
• Memory: Nonvolatile memory retains lockout history and runtime data
• Weight: 1 lb 15 oz (0.9 kg)
• Dimensions (with Q7800A): 5″ W x 5″ H x 5-1/4″ D
• Dimensions (with Q7800B): 5″ W x 5″ H x 6-3/32″ D
• Temperature Range: -40°F to +140°F (-40°C to +60°C)
• Vibration Tolerance: 0.5 G
• Condition: New

Key Features

• Automatic burner sequencing and flame safeguard
• Compatible with UV, IR, and flame rod detection via plug-in amplifiers
• Modular design allows quick replacement and flexible configuration
• Built-in LED status indicators for fast diagnostics
• Retains burner runtime and lockout history in memory
• Supports remote annunciation, reset, and keyboard display modules
• Designed for safe, reliable operation in demanding combustion environments

Compatible Accessories

• Q7800A / Q7800B Subbases
• ST7800A Plug-In Purge Timer Card
• S7800A Keyboard Display Module
• R7847, R7848, R7849, R7851, R7852, R7861, R7886 Amplifiers
• Honeywell flame rods, UV/IR flame sensors

Industry Applications

• Commercial and industrial boilers
• Process heating systems
• Fuel-fired HVAC systems
• Burner management panels and safety interlock systems

Installation & Maintenance Notes

• Ensure subbase and purge timer card are correctly installed
• Use a compatible flame amplifier for your sensor type
• Configure purge duration based on application requirements
• Monitor flame signal strength during startup and operation
• Review lockout codes using LED indicators or optional display