Honeywell RM7890A1056 7800 Series Burner Control

The RM7890A1056 is a microprocessor-based 7800 Series primary burner control relay module manufactured by Honeywell for automatically fired gas, oil, coal, or combination fuel single-burner applications. Operating on 120 VAC, it provides automatically sequenced burner firing, flame supervision, system status indication, and self-diagnostics for on-off primary burner control. This unit supports intermittent pilot operation, programmable Valve Proving System (VPS) sequences, and selectable pilot flame establishing periods.

Sequence Logic and Flame Supervision Features

The relay module sequences burner start-up through pre-ignition, pilot ignition, main flame execution, and post-purge stages. Field technicians can configure trial-for-ignition parameters to suit specific burner hardware and fuel requirements:

• Pilot Flame Establishing Period: Field-selectable for either a 4-second or 10-second trial for ignition.
• Ignition Type: Configured for intermittent pilot operation.
• Safety & Monitoring: Integrates a pre-ignition sequence and supports an optional programmable Valve Proving System (VPS) to verify fuel valve closure integrity.

Operating Voltage and Mechanical Characteristics

The unit operates on 120 VAC (+10/-15%) at 50 Hz or 60 Hz power lines. It mounts directly onto a standard 7800 Series subbase, forming a modular assembly with plugged-in flame signal amplifiers and purge timer cards. The complete module weighs 3.00 lbs and functions in ambient operating temperatures ranging from -40 deg C to +60 deg C (-40 deg F to +140 deg F).

Frequently Asked Questions

Q: What power input is required to operate the Honeywell RM7890A1056 relay module?

A: The module requires 120 VAC (+10/-15%) line voltage at 50 Hz or 60 Hz.

Q: What pilot flame establishing periods can be configured on the RM7890A1056?

A: The module supports field configuration for either a 4-second or 10-second pilot flame establishing period.

Q: Can the RM7890A1056 be used with combination gas/oil burners?

A: Yes, it is rated for automatically fired single-burner applications using gas, oil, coal, or combination fuels.