Complete repair guide for the Newmar Bay Star – Furnace Igniter & Control Board Replacement. Follow these steps to diagnose and fix the issue yourself.
Parts & Tools You’ll Need
- Suburban RP-35Q 35,000 BTU/h RV Replacement Core for Suburban Furnace Series SF-35, SF-35Q, SF-42, SF-42Q, and SF-Q (2609A) — Suburban/Atwood RV furnace (replacement unit)
- Fit For Suburban RV Furnace Parts 232286,Single Probe Gas Furnace Igniters Electrode with Wire Assembly, Camper Furnace For Suburban 232286 Above 934701426 SF-20, SF-25, SF-30, SF-35 (SF Series) — Furnace igniter electrode
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace sail switch
- 520814 Rv Water Heater Module Board Ignition Control Circuit Board Compatible with Suburban Furnace SW4D, SW6D, SW6DE, SW12D, SW6DEM RV Water Heaters,Replace 520814 520820 520871 33550L (With lid) — Furnace circuit board / control board
- DTAIR 33082 Sail Switch Replacement for Select Dometic Atwood RV Furnace(Pack of 2) — Furnace high-limit switch
- Suburban 232684 RV Furnace 12v SF-Series DC Blower Motor, SF-35, SF-35F, SVF-35, SF-42, SF-42F OEM Caliber — Furnace blower motor (12V DC)
- RV Carbon Monoxide & Propane Gas Alarm, Briidea Dual LP/CO Detector with Separate LED Indicator Light, 100dB Loud Alarm, 12 VDC, Black — Propane/CO combo detector alarm
- FKM Pro Digital Multimeter Tester TRMS 6000 Counts,Smart Rechargeable Voltmeter 5″Color LCD,Auto-Ranging Automotive Multimeters,for AC/DC Current/Voltage,NCV,Ohm,Capacitance,Resistance,Continuity,Temp — Digital multimeter
Step 1: Diagnose Furnace Ignition Failure
Start by turning on your RV furnace and listening for the igniter clicking sound—a rapid ticking indicates the igniter electrode is attempting to fire. Use your digital multimeter set to the 20V DC setting to test the furnace circuit board’s output voltage at the igniter terminals; you should read between 12-14V DC when the system calls for heat. If you’re getting no voltage or hearing no clicking, the problem lies with either the igniter electrode itself or the furnace control board, both of which will need replacement.
Step 2: Disconnect Power and Propane Supply
Turn off the furnace at the thermostat and locate your RV’s 12V DC breaker panel—switch off the furnace circuit breaker to cut all electrical power. Next, shut off the propane supply at the main tank valve and allow the system to depressurize for at least 2-3 minutes before proceeding. This dual shutdown prevents both electrical hazards and potential propane leaks during component removal.
Step 3: Remove Furnace Access Panel and Components
Locate the furnace access panel (typically secured with 4-6 Phillips-head screws on the Newmar Bay Star) and remove it to expose the internal combustion chamber and control board. Carefully disconnect the electrical connectors from the furnace igniter electrode and the sail switch—take a photo of the connector positions before disconnection to ensure proper reinstallation. Note the exact routing of these wires as you’ll need to replicate it with your replacement components.
Step 4: Replace Igniter Electrode and Sail Switch
Unscrew the furnace igniter electrode (typically a single 1/4-inch fastener) from its mounting bracket inside the combustion chamber and carefully remove it. Install your replacement furnace igniter electrode in the same position, ensuring it sits approximately 1/8-inch from the burner flame pathway and is secured firmly. Similarly, unbolt the sail switch (a small safety device that detects air flow) and install the replacement unit in its exact original position, verifying all electrical connectors are fully seated.
Step 5: Install New Furnace Control Board
Locate the furnace circuit board mounted on the exterior of the combustion chamber housing and disconnect all wiring harnesses—typically 3-4 connectors including the 12V DC main power lead and the thermostat wire pair. Unbolt the old control board (usually 2-3 mounting bolts) and carefully remove it, noting the thermal sensor location on the high-limit switch. Mount your replacement furnace circuit board in the identical position using the original bolts and reconnect each wire harness in the same configuration, ensuring no connector is loose or partially seated.
Step 6: Reconnect Propane and Verify Fuel Line Integrity
Before restoring propane, inspect the propane line connection at the furnace burner assembly for any visible cracks or corrosion—this line should feel hand-tight and show no signs of leaking. Turn the propane supply valve back on at the tank and listen for any hissing sounds near the furnace connections; if you detect propane odor, immediately close the main valve and check all fittings. Apply a thin soap solution around all propane connections to confirm there are no bubbles forming, which would indicate a leak requiring tightening or replacement of the fuel line.
Step 7: Test Furnace Operation and Monitor Performance
Restore power by switching the furnace breaker back on and set your thermostat to heat mode with the temperature 5 degrees above the current cabin temperature. You should hear the igniter electrode clicking within 10-15 seconds, followed by a solid ignition flame visible through the access opening. Allow the furnace to run for 10 minutes while you monitor the blower motor output (warm air should flow consistently from all vents), then verify your Propane/CO combo detector alarm shows normal operation and no fault codes appear on the control board display.