Nexus Triumph – Furnace Igniter & Control Board Replacement

Nexus Triumph – Furnace Igniter & Control Board Replacement

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Complete repair guide for the Nexus Triumph – Furnace Igniter & Control Board Replacement. Follow these steps to diagnose and fix the issue yourself.

Parts & Tools You’ll Need

Step 1: Diagnose Igniter and Control Board Failure

Start by disconnecting the RV’s 12V DC power supply at the main battery disconnect switch, then locate your Suburban/Atwood furnace unit typically mounted in a belly cabinet or under-floor compartment. Use your digital multimeter to test for continuity across the furnace igniter electrode—you should read between 4-14 ohms when functioning properly; any reading above 20 ohms or infinite resistance indicates a failed igniter. Next, inspect the circuit board for visible damage such as burnt components, corrosion around the connector pins, or cracked solder joints; also note any error codes or unusual clicking sounds from the control board relay, which suggest control board failure.

Step 2: Access the Furnace Assembly Safely

Ensure propane supply is shut off at the tank valve and allow 10-15 minutes for any residual gas to dissipate before opening the furnace compartment. Remove the RV furnace access panel by unscrewing the four corner fasteners (typically ¼-inch bolts), then carefully slide the panel away to expose the burner assembly, igniter electrode, and control board mounted on the right interior wall. Take photos of the wire connections at the sail switch, igniter electrode, and control board before disconnecting anything, as these serve as your reassembly reference.

Step 3: Remove Igniter Electrode and Connectors

Locate the furnace igniter electrode—a ceramic-tipped probe extending roughly 3/8 inch into the burner chamber—and carefully disconnect the spade-connector terminal from its mounting bracket using needle-nose pliers. Unscrew the single mounting bolt (usually a 10mm hex head) that secures the igniter electrode bracket to the furnace body, then gently withdraw the electrode assembly, being careful not to crack the ceramic tip. Clean the igniter recess with a dry cloth to remove any accumulated soot or debris before installing the replacement igniter electrode.

Step 4: Install New Igniter Electrode Precisely

Position the replacement furnace igniter electrode into the mounting bracket, ensuring the ceramic tip is centered in the burner chamber approximately 3/8 inch from the burner surface—this gap is critical for proper spark-to-fuel ignition. Secure the electrode with its mounting bolt, tightening to a snug fit (approximately 25-30 inch-pounds) without over-torquing, which can crack the ceramic. Reconnect the spade-terminal connector firmly onto the electrode post and verify it won’t slip off under gentle pulling.

Step 5: Replace Control Board with New Unit

Disconnect all three wire connectors from the old furnace circuit board by carefully depressing the connector tabs and pulling straight away—typically you’ll have connectors for the igniter electrode, sail switch, and blower motor circuit. Remove the two mounting screws securing the control board to the furnace chassis (usually 8mm Phillips head), and slide the old board out of its bracket. Install the new furnace circuit board into the bracket, align the connector ports, and secure with the two mounting screws, then reconnect all three wire harnesses, ensuring each connector clicks fully into place until the retention tabs lock.

Step 6: Verify Sail Switch and Limit Switch Function

With the new control board installed, manually inspect the sail switch (a thin metal flapper in the blower air stream) to ensure it moves freely without sticking or binding—gently push it to confirm proper deflection. Check that the furnace high-limit switch mounted on the heat exchanger moves smoothly when pressed and makes an audible click at approximately 160-170°F (you can test with a heat gun if needed, though this step can wait for operational testing). Confirm all switch connectors are fully seated on the control board terminals by attempting to wiggle them—they should not move.

Step 7: Test System Operation and Safety Systems

Reconnect the 12V DC power at the main battery disconnect and turn on the furnace via your RV thermostat, listening for an immediate clicking sound (spark ignition) followed by the whoosh of propane ignition within 5 seconds. Observe the blower motor activation approximately 15-30 seconds after burner ignition, and verify the furnace maintains steady flame through a complete heating cycle without stalling or reigniting. Finally, activate your propane/CO combo detector alarm to confirm it functions properly, indicating your safety systems are operational, and check that the furnace shuts down cleanly when the thermostat reaches setpoint temperature.