What Additional Components Are Needed for a Honeywell RM7800 Series Burner Control?

Apex Controls supplies Honeywell RM7800 series burner control components from U.S. inventory with fast shipping and expert technical support.
Whether you’re sourcing a complete RM7800 system or compatible relays, transformers, or flame detectors, Apex Controls offers current pricing, availability, and ordering assistance for combustion control applications.

The Honeywell RM7800 Series is one of the most trusted flame safeguard systems in commercial and industrial burner applications. Known for its reliability, self-diagnostics, and modular design, it provides safe sequencing and protection for gas, oil, and combination-fuel systems. However, the RM7800 relay module alone is not a complete system — it requires several key companion modules to operate properly. Below, we break down all the essential Honeywell RM7800 burner control components, including subbases, flame amplifiers, keyboard display modules, and purge timers — with links to each product.

🧱 Core Honeywell RM7800 Burner Control Components

According to Honeywell Installation Manual 32-00142, each RM7800 relay module requires the following accessories for proper operation

You can order Honeywell RM7800 relays, transformers, burners, flame scanners, and other control modules directly through Apex Controls, with live pricing and availability shown below.

Where to Buy RM7800 Series Components

1️⃣ Wiring Subbase

Apex Controls supplies Honeywell RM7800 relays for control panels, with inventory available for immediate shipment

Models: Q7800A1005, Q7800B1003, Q7800B1011, Q7800A2005, Q7800B2003, Q7800B2011

The wiring subbase provides all electrical connections for line voltage, limits, and interlocks. It forms the physical foundation for the relay, allowing easy plug-in installation and service replacement.

🔹 Subbase Options

• Q7800A1005 – Two-sided subbase for panel-mount applications

• Q7800B1003 / Q7800B1011 – Four-sided subbases for burner or wall-mount installations

🔹 Series 2000 Updates

Honeywell introduced new subbases for the latest RM7800 controls:

• Q7800A2005, Q7800B2003, and Q7800B2011

• Designed for all models with a “2” in the part number (e.g. RM7800A2012)

• Easily identified by the standing grounding pin in the corner

💡 Note: 1000-series and 2000-series subbases are not interchangeable.

2️⃣ Flame Amplifier Modules

Apex Controls supplies Honeywell RM7800 relays for control panels, with inventory available for immediate shipment

Models: R7824, R7847, R7848, R7849, R7851, R7852, R7861, R7886 series

The flame amplifier detects the flame signal from the scanner or flame rod and tells the RM7800 whether a stable flame is present. If no signal is detected, the amplifier forces a lockout to prevent unsafe operation.

Each amplifier must match the type of detector (UV, IR, optical, or rectification).

🔍 Common Amplifier Models and Applications

⚙️ Amplifier Highlights

• Plug-in design for quick installation

• Self-check circuitry tests amplifier and detector up to 12 times/minute

• Flame-failure response time (FFRT): 0.8 – 3.0 seconds

• Flame-signal range: 0 – 5 V DC

• Color codes: 🟢 Rectification 🟣 Ultraviolet 🔴 Infrared ⚪ Optical 🔵 Adjustable UV

3️⃣ Keyboard Display Module

Apex Controls supplies Honeywell RM7800 relays for control panels, with inventory available for immediate shipment

Models: S7800A1001 (1st Gen), S7800A1142 (2nd Gen), S7800A2142 (3rd Gen)

The Keyboard Display Module (KDM) serves as the interface for setup, operation, and diagnostics. It shows real-time status, flame signal strength, timing, and lockout codes directly on the control.

🧩 Generation Breakdown

All KDMs are backward compatible and plug directly into the relay face.

🧠 Key Functions

• Displays burner sequence status (Purge, Pilot, Main Flame, Run, Post-Purge)

• Shows flame-signal voltage (0 – 5 V DC)

• Stores lockout history and fault codes

• Allows adjustment of purge timing and valve-proving

• Provides onboard diagnostics for troubleshooting

💡 For modern installations, choose the S7800A2142 for the best readability and compatibility.

4️⃣ Purge Timer

Apex Controls supplies Honeywell RM7800 relays for control panels, with inventory available for immediate shipment

Models: ST7800A and ST7800C Series

The purge timer determines how long the burner’s blower motor operates before ignition (pre-purge) and after shutdown (post-purge). This ensures unburned fuel vapors are safely cleared from the combustion chamber.

Honeywell’s ST7800 timers plug directly into the subbase alongside the RM7800 relay and are available in various timing configurations.

🔹 ST7800A Series

🔹 ST7800C Series

⚙️ Purge Timer Highlights

• Adjustable purge durations from 2 seconds to 30 minutes

• Post-purge capability up to 60 minutes (via KDM)

• Plug-in design for quick configuration

• Compatible with RM7800 and EC7800 controls

Apex Controls specializes in Honeywell combustion and burner safety products, helping customers avoid long lead times, incorrect substitutions, and critical component availability issues.

🧠 Final Thoughts on Honeywell RM7800 accessories

Plant engineers, service technicians, and combustion system installers often source RM7800 series burner controls and related parts from Apex Controls for dependable pricing, fast delivery, and technical support.

A complete Honeywell RM7800 system includes:

• Correct Wiring Subbase

• Compatible Flame Amplifier & Detector

• Keyboard Display Module (S7800A1001 / A1142 / A2142)

• Purge Timer (ST7800A or ST7800C series)

Each module plays a vital role in safe burner operation, flame supervision, and service diagnostics. Using genuine Honeywell components ensures long-term reliability and compliance.

Disclaimer: This article is not intended to serve as a guide for selecting burner control components. Each system has unique requirements, and configuration should always be performed by an experienced burner control technician.