Complete repair guide for the Forest River Berkshire – 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 Failure & Gather Tools
Begin by confirming the furnace won’t ignite—listen for the blower motor running without heat production, which typically indicates an igniter electrode or control board failure. Gather your digital multimeter, screwdrivers (Phillips and flathead), wire strippers, and a socket set, then locate your Forest River Berkshire’s furnace compartment (usually under the dinette or rear bedroom). Turn off all power at the RV’s main breaker and propane supply valve before proceeding, then allow 10 minutes for any residual gas to dissipate.
Step 2: Remove Old Igniter Electrode Assembly
Access the furnace combustion chamber by removing the outer access panel with your screwdriver. Locate the igniter electrode—a thin ceramic-tipped rod positioned near the burner assembly—and note its orientation before disconnecting the two-pin spade connector. Carefully slide the electrode out of its mounting bracket (typically a simple friction fit), taking care not to crack the ceramic tip, as this component costs $40–$60 to replace and is easily damaged.
Step 3: Test & Replace Control Board if Needed
Using your digital multimeter set to voltage mode, test the control board’s output terminals for 24V AC when the ignition cycle begins—if you read 0V or fluctuating voltage, the control board is faulty. Remove the circuit board by unbolting its two mounting brackets and carefully disconnecting all spade connectors, noting their positions with a phone photo. Install the replacement furnace circuit board in reverse order, ensuring all connections are snug and the board sits flat against its mounting surface without twisting wires.
Step 4: Install New Igniter Electrode Precisely
Slide the new furnace igniter electrode into its mounting bracket, positioning it so the ceramic tip sits approximately 0.125 inches (3mm) from the burner opening—too close causes premature failure, too far prevents proper ignition. Reconnect the two-pin spade connector, ensuring both terminals click firmly into place and wires aren’t pinched. Double-check that the electrode isn’t touching any metal surfaces, as this will short the ignition circuit and prevent ignition.
Step 5: Verify High-Limit & Sail Switch Function
Inspect the high-limit switch (typically a bi-metal safety device near the heat exchanger) and furnace sail switch (a reed switch triggered by blower airflow) for any visible corrosion or loose mounting. Using your multimeter set to continuity mode, confirm the sail switch closes when you manually push its lever—it should beep or show 0Ω resistance. If either switch fails the continuity test, replace it following the same bracket removal and connector disconnection process as the control board.
Step 6: Reconnect All Systems & Check Seals
Reattach the furnace’s outer access panel and ensure the combustion chamber seal is intact—use a gasket scraper to remove old sealant, then apply a thin bead of high-temperature silicone around the panel perimeter before reinstalling. Reconnect the propane supply line to the furnace inlet fitting and hand-tighten, then verify the connection with soapy water (bubbles indicate a gas leak requiring further tightening). Turn the main power breaker back on and verify the propane valve is fully open by checking for audible gas flow.
Step 7: Test Ignition & Monitor for Proper Operation
Set the furnace thermostat to heat mode and target temperature above the current cabin temperature, then listen for the ignition sequence—you should hear a clicking electrode sound followed by burner ignition within 3–5 seconds. Let the furnace run for 10 minutes on high, monitoring that warm air exits the vents consistently and the blower motor doesn’t stall. Test your propane/CO combo detector to ensure it reads zero CO levels after 5 minutes of furnace operation; if CO levels exceed 10 ppm, shut down immediately and inspect for incomplete combustion or exhaust leaks.