Honeywell RM7840L1018/U Auto Programming Controller

The RM7840L1018/U is a microprocessor-based integrated burner control engineered for automatically fired gas, oil, coal, or combination fuel single burner applications. It executes automatic burner sequencing, flame supervision, and system diagnostics, providing advanced safety and functional capabilities supported by nonvolatile memory and interchangeable plug-in flame amplifiers.

System Architecture and Compatibility

Designed to operate on 120 Vac (+10%, -15%) at 50 or 60 Hz, the control requires a Q7800A or Q7800B Universal Wiring Subbase, an ST7800A Plug-in Purge Timer Card, and a compatible flame signal amplifier such as the R7847, R7848, R7849, R7851, R7852, R7861, or R7886 series. It features five sequence-indicating LEDs, a five-function run/test switch, and access points for external electrical voltage checks.

Safety and Operational Timings

The unit provides selectable pilot flame establishing periods of 4 or 10 seconds and main flame establishing periods of 10, 15, 30 seconds, or intermittent operation, alongside a 15-second postpurge and 5-second early spark termination. Prepurge timing is determined by the installed ST7800A purge timer card, while internal logic manages running interlocks and safety lockouts.

Technical Parameters

Frequently Asked Questions

Q: What components are required to operate the Honeywell RM7840L1018/U controller?

A: It requires a Q7800A or Q7800B Universal Wiring Subbase, an ST7800A Plug-in Purge Timer Card, and a compatible flame signal amplifier.

Q: How is the prepurge interval determined for this burner control?

A: The prepurge time is determined directly by the specific ST7800A plug-in purge timer card installed in the system.