Honeywell S87D1020 Direct Spark Ignition Module
$245.00
Condition: Used
(Tested)
6 in stock
Honeywell S87D1020 Direct Spark Ignition Module (4-Second Trial for Ignition)
The Honeywell S87D1020 (MPN: S87D1020/U) is a solid-state, low-voltage direct spark ignition (DSI) control module designed for single-trial ignition sequences in commercial, industrial, and marine gas-fired combustion systems. It orchestrates the entire burner cycle: opening the main gas valve, generating a capacitive high-voltage electrical discharge across the spark electrode, and continuously monitoring flame rectification via a dedicated, independent remote flame sensing rod (two-rod configuration).
Technical Specifications: Honeywell S87D1020
| Technical Parameter | Specification Rating |
|---|---|
| Manufacturer & Series | Honeywell S87 Series DSI |
| Manufacturer Part Number (MPN) | S87D1020 / S87D1020/U |
| Operating Voltage / Frequency | 24 VAC (18-30 VAC range), 50/60 Hz |
| Ignition Sequence | 0s Prepurge, 4.0s Trial for Ignition, 100% Lockout |
| Flame Detection System | Two-Rod Rectification (Separate Sense Rod) |
| Gas Valve Contact Rating | 2.0 A Continuous @ 24 VAC |
| Flame Response / Re-Ignition Time | 0.8 Seconds Max @ 5.0 uA DC |
| High Voltage Generation | 15 kV Open Circuit Potential via 1/4″ Stud Base |
| Overcurrent Protection | External 3.0 Amp Replaceable Blade Fuse |
| Terminal Style | 1/4″ (6.35 mm) Male Quick-Connect Spade Terminals |
| Ambient Rating | -40 deg C to +79 deg C (-40 deg F to +175 deg F) |
Key Features
- 4-Second Single-Trial Safety Lockout: Immediately de-energizes main gas valve outputs if flame ionization fails to prove within 4 seconds, preventing dangerous unburnt gas accumulation in combustion chambers.
- Dedicated Two-Rod Flame Rectification: Utilizes separate spark discharge and flame detection electrodes to eliminate circuit crosstalk, false flame signals, and electrical feedback into the flame amplifier.
- Fast Response on Flame Loss: Boasts an ultra-rapid 0.8-second flame failure response time with immediate 0.8-second re-ignition sequencing before safety shutdown.
- Direct Fault Telemetry & Overcurrent Protection: Equipped with a dedicated 24 VAC auxiliary alarm terminal for remote SCADA/annunciator integration and a field-replaceable 3 A ATO/ATC automotive-style fuse.
Terminal Allocations & Wiring Pinout
| Terminal Designation | Physical Connector | Functional Description / Wiring Destination |
|---|---|---|
| 24V (TH) | 1/4″ Male Spade | 24 VAC Power Supply input from thermostat / burner management system call-for-heat circuit. |
| VALVE | 1/4″ Male Spade | Switched 24 VAC (2.0 A max) output wired to the main gas combination control valve coil (e.g., Honeywell VR8205/VR8305). |
| GND (BURNER) | 1/4″ Male Spade | Primary earth/chassis ground reference connection; must be bonded directly to the burner ground bracket for flame current return loop. |
| 24V (GND) | 1/4″ Male Spade | 24 VAC Transformer secondary neutral / common return connection. |
| SENSE | 1/4″ Male Spade | Dedicated micro-amp DC input from remote flame rod (Q354A, Q366, or equivalent). |
| ALARM | 1/4″ Female Spade | Switched 24 VAC output energized only when the module enters safety lockout mode; drives external warning lights, relays, or alarm horns. |
| SPARK STUD | 1/4″ Stud Base | High-tension post output for heavily insulated 7 mm / 16 AWG ignition lead wired to spark igniter electrode. |
Part Number Cross-References & Direct Replacements
- Honeywell Legacy Units: S825D, S825D1001, S825D1019, S87D1004, S87D1012, S87D1020, S87D1020/U
- Functional Field Replacements: Resideo S8701D1000, S8702D1009, White-Rodgers 50D50-842 (requires field verification of wiring layout)
Applications
- Marine Auxiliary Systems: Gas-fired inert gas generators (IGG), exhaust incinerators, marine galley ovens, thermal fluid deck heaters, and accommodation auxiliary water heaters.
- Commercial / Industrial Combustion: Atmospheric and power gas boilers, unit heaters, rooftop makeup air units (MAU), duct furnaces, commercial fryers, and industrial radiant tube heaters.
- Fuel Media: Fully rated for both Natural Gas (NG) and Liquefied Petroleum Gas (LP / Propane) systems.
Frequently Asked Questions
What causes a Honeywell S87D1020 to lock out immediately after sparking?
Safety lockout occurs when the control board fails to detect a continuous flame rectification signal within its 4-second Trial for Ignition (TFI) window. Primary root causes include a disconnected or carbon-fouled remote flame sensor rod, inadequate earth bonding at the GND (BURNER) terminal, reversed 24V line/neutral polarity, or a faulty gas combination valve coil failing to release fuel.
Can the S87D1020 be used on single-rod ignition systems?
No. The S87D1020 is engineered strictly for two-rod systems, meaning spark discharge and flame rectification sensing take place on separate physical probes. For single-rod applications where spark and sensing share one electrode, you must specify the Honeywell S87A or S87B series.
How do you reset the S87D1020 module after a safety lockout?
Because the module features automatic non-volatile lockout upon flame failure, it must be reset by interrupting the 24 VAC supply power. Lower the operating thermostat or BMS heating demand below the cut-in setpoint for at least 30 to 60 seconds, then restore the call for heat. If power is un-cycled, the module remains locked out with the 24V alarm terminal energized.
What is the purpose of the 3-amp onboard fuse?
The fast-acting 3.0 A blade fuse protects the external 24 VAC power transformer and internal circuit traces against dead shorts or over-current surges occurring in the gas valve wiring harness, external thermostat loop, or auxiliary alarm circuitry.
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