UIB-S Small Universal Ignitor Board | 12V DC RV Furnace & Water Heater Ignition Control

UIB-S Small Universal Ignitor Board – 12V DC RV Furnace & Water Heater Ignition Control

The ignitor board is the ignition control module for your RV furnace or water heater, managing the ignition sequence, flame sensing, safety lockout, and timing. When the ignitor board fails, your furnace or water heater may fail to ignite, cycle on and off, or lock out completely.

This UIB-S small universal 12V ignitor board is designed as a replacement for Atwood, Dometic, and Suburban furnace and water heater ignition control boards. Its compact size makes it ideal for installations where space is limited, and it features spark ignition, flame sensing, trial ignition timing, and safety lockout.

Compatibility

• Atwood Hydro Flame furnaces (85-IV, 89-III, AFMD, 7900-II series)
• Atwood water heaters (GC6AA, G6A-8E, G16-EXT, GC10A)
• Dometic DFMD, DFSI series furnaces
• Dometic WH-6GA, WH-9GA water heaters
• Suburban SF, NT series furnaces
• Suburban SW6D, SW10D water heaters (select models)
• Most 12V RV furnaces and water heaters with spark ignition
• Replaces board numbers: UIB-S, 520814, 520820, 31501, 33488, 33727, 91367

Specifications

Installation Guide

1. Safety first: Disconnect 12V power at the battery. Turn off propane supply. Allow the furnace/water heater to cool completely.
2. Access the board: Remove the exterior access panel. The ignitor board is typically mounted near the burner assembly.
3. Document connections: Take photos of all wiring connections before disconnecting. Note which wires go to which terminals.
4. Disconnect wires: Remove the wire connectors from the old board terminals. Note the position of each wire.
5. Remove old board: Unscrew the 2 mounting screws holding the board.
6. Install new board: Mount the new UIB-S board in the same position. Secure with mounting screws.
7. Reconnect wires: Connect all wires to the corresponding terminals (refer to your photos). Ensure all connections are secure.
8. Test operation: Reconnect 12V power. Turn on propane. Set the thermostat to call for heat. Verify the ignition sequence: pre-purge → spark ignites → flame is sensed → continues. Check for proper operation through at least one complete cycle.

Ignition Sequence

1. Call for heat: Thermostat closes, sending 12V signal to the board.
2. Pre-purge: Combustion fan runs for 15 seconds (fan models only).
3. Trial ignition: Spark igniter activates, gas valve opens. Board attempts ignition for up to 8 seconds.
4. Flame sense: If flame is detected, spark stops, gas valve stays open.
5. Retry: If no flame, board retries up to 3 times.
6. Lockout: After 3 failed attempts, board locks out for 30 minutes. Manual reset required.
7. Post-purge: When thermostat opens, gas valve closes, fan runs for 30 seconds.

Frequently Asked Questions

Q: What’s the difference between UIB-S and UIB64?

A: UIB-S (Small) and UIB64 are both universal ignitor boards, but they differ in size and connector type. The UIB-S is a compact board with wire leads (spade terminals) and a 2-screw mounting. The UIB64 is a larger board with pin-style connectors (PINS version) and a 4-screw mounting, designed to directly replace Atwood 4 and 6 position edge-style boards. Both boards have the same functionality (spark ignition, flame sensing, 3 trial ignitions, 30-minute lockout). Choose the one that matches your original board’s connector type and mounting footprint.

Q: How do I reset the board after a lockout?

A: After a safety lockout (3 failed ignition attempts), the board will remain locked for 30 minutes. To reset immediately, disconnect 12V power for at least 10 seconds, then reconnect. This clears the lockout and allows a new ignition attempt. If the unit continues to lock out, there is an underlying problem (no gas supply, blocked burner, bad electrode, etc.) that needs to be addressed before resetting again.

Q: Can I use this board in a water heater without a fan?

A: Yes. The fan control output is optional. If your water heater doesn’t have a combustion fan, simply leave the fan output unconnected. The board will still perform spark ignition and flame sensing normally. The pre-purge and post-purge timers will still run but won’t affect operation without a fan.

Q: What should the spark gap be?

A: The spark electrode gap should be approximately 1/8″ (3mm). Too wide a gap may prevent sparking; too narrow may cause weak spark. Check and adjust the electrode gap if you’re experiencing ignition problems. The electrode should be positioned so the spark jumps from the electrode tip to the burner tube or ground strap.

Related Products

• FAN 50 PLUS Ignitor Board — Universal 12V furnace ignitor board with fan control (PINS version)
• UIB64 Universal Ignitor Board — Atwood 4/6 position edge-style replacement
• Suburban Ignition Electrode (232286) — Replacement spark probe for furnaces

Need help finding the right ignitor board for your furnace or water heater? Contact our technical team with your model number. Free shipping and duties included.