Honeywell RM7850A1019/U Burner Programming Control

The RM7850A1019/U is an advanced burner programming control engineered to manage commercial and industrial burner-boiler operations. Built to meet European Community timings (LHL, high/low fire proving), it incorporates five diagnostic LEDs, a run/test switch, and nonvolatile memory to retain history and lockout status during power loss.

System Architecture and Compatibility

The control operates on 120 Vac (-15%, +10%) at 50 or 60 Hz and interfaces with compatible Honeywell flame detectors, plug-in amplifiers (such as R7847, R7849, R7861, or R7886), and ST7800A purge timer cards. It requires a Q7800A or Q7800B universal wiring subbase and supports local or optional remote annunciation alongside external voltage check access points.

Safety and Operational Timings

Featuring a 3 or 5 second pilot and main flame establishing period with a 15-second postpurge, the unit executes programmed preignition, airflow checks, and intermittent second-stage pilot valve operation. Prepurge intervals are determined by the inserted ST7800A timer card, while system interlocks trigger secure lockouts under fault conditions.

Technical Parameters

Frequently Asked Questions

Q: What subbases are compatible with the Honeywell RM7850A1019/U control?

A: It requires either the Q7800A or Q7800B Universal Wiring Subbase for installation and wiring termination.

Q: How is the prepurge time configured for this burner control?

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