Technical Overview
The Honeywell RM7850A1019 is a microprocessor-based relay module for automatically fired single-burner systems using gas, oil, or combination fuels. This unit provides automatic burner sequencing and comprehensive flame supervision for full modulation applications. The complete system requires a Q7800 wiring subbase, an R78XX amplifier, and an ST7800 purge timer card for proper operation. A non-volatile memory retains fault history and lockout status even after total power loss. The module delivers visual status indication through five front-panel LEDs. It specifically handles modulating burners with High Fire and Low Fire Proving logic.
Technical Specifications
| Parameter | Specification |
|---|---|
| Manufacturer | Honeywell |
| Model Number | RM7850A1019 |
| Product Type | Relay Module / Programming Control |
| Voltage | 120 Vac (+10/-15%) |
| Frequency | 50/60 Hz (±10%) |
| Power Dissipation | 10 W maximum |
| Maximum Connected Load | 2000 VA |
| Fuse Rating | 15 A maximum, Type SC Fast Blow |
| Pilot Flame Establishing Period | 3 or 5 seconds (selectable) |
| Main Flame Establishing Period | 3 sec, 5 sec, or intermittent |
| Post-Purge Time | 2 seconds |
| Operating Temperature | -40°C to +60°C |
| Storage Temperature | -40°C to +66°C |
| Humidity Rating | 85% RH continuous, noncondensing |
| Vibration Tolerance | 0.5G environment |
| Dimensions (with Q7800A) | 127 x 127 x 133 mm |
| Dimensions (with Q7800B) | 127 x 127 x 155 mm |
| Weight | 0.7 kg |
| Mounting Type | Panel mount with Q7800 subbase |
| Required Components | Q7800A/B subbase, R78XX amplifier, ST7800 purge timer |
| Approvals | FM Approved, CE (EN298), UL, CSA |
| Country of Origin | USA |
Key Features
Full Modulation Support – This module includes High Fire and Low Fire Proving logic for precise modulating burner control.
Advanced Diagnostics – The built-in self-diagnostics and troubleshooting functions help operators identify faults quickly.
Non-Volatile Memory – The module retains history files and lockout status after power loss, ensuring data persistence.
Plug-in Amplifier Design – Interchangeable amplifiers simplify field replacement and customization for various flame detectors.
Visual Status Indication – Five LEDs provide sequence information, and a Run/Test Switch allows manual control.
Compatible Detectors – The unit works with existing Honeywell flame detectors, reducing upgrade complexity.
Selectable Flame Timing – Adjustable pilot and main flame establishing periods provide application flexibility.
Required Components
The Honeywell RM7850A1019 requires several separately purchased components: a Q7800A or Q7800B Universal Wiring Subbase, a compatible plug-in flame signal amplifier, and an ST7800A Plug-in Purge Timer Card. The optional S7800 Keyboard Display Module provides enhanced status indication and configuration capabilities.
Applications
This relay module excels in industrial burner management for boilers, furnaces, and process heaters. It delivers reliable performance in power generation, chemical processing, and manufacturing environments where modulating burner control with full flame supervision is critical.
Details
| Weight | 0.2 kg |
|---|---|
| Dimensions | 85 × 65 × 30 mm |
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