Suburban RV Heater Not Working on Gas
The Short Answer: Suburban gas dead with electric still hot is LP, DSI, igniter, solenoid, or a thermal cutoff — not a rotten tank. Confirm bottles and bypass, hear spark with the gas off, and stop cycling if you smell propane. Standing-pilot Suburbans fail on thermocouple; Phase 3 units have no pilot. Do not loosen LP flares.
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Search Intent & The Real Problem
The interior gas switch is on. Electric still makes a lukewarm shower on shore power. Gas does nothing — or it ticks at the exterior door and dies. Dual-fuel Suburbans (SW6DE, SW10DE, SW16DE and cousins) have two independent heat paths. Gas failure with electric alive means the tank can hold water. You are on ignition and fuel.
Phase 3 is Suburban’s DSI platform — spark, no standing pilot. Full board logic: Phase 3 troubleshooting. Electric-side ECO: SW10DE and Suburban reset. Click with no spark at the electrode: Suburban igniter. Atwood/Dometic boards are not Suburban boards — Atwood clicking.
What other guides get wrong
They start with “faulty thermocouple” on a Phase 3 heater that has none. They mix Dometic DSI boards with Suburban. They tell you to soap-test fittings while the igniter is still sparking. And they send you to clean an electric element because the gas half is dead. Wrong fuel path.
Step-by-Step Troubleshooting
Step 1: Prove which half is dead
| What works | Look at first |
|---|---|
| Electric OK, gas dead | LP, DSI/pilot, igniter, solenoid, thermal cutoff |
| Gas OK, electric dead | 120 V, ECO, element — not this article |
| Both dead | Empty tank, bypass, winterized, or no power and no LP |
- Required tools: Flashlight, the cabinet diagram, a hot faucet.
Electric switch off while you diagnose gas so you do not dry-fire the element.
Step 2: Water in the tank, bypass in normal
- What to look for: Three-valve bypass in the heat path. Steady stream at a hot faucet, no sputter. A winterized tank is empty even if the lines are wet. An ECO that opened after a dry fire will kill gas, electric, or both depending on the limit.
- Required tools: Open a hot tap until it runs solid.
Do not spark a DSI on a tank you have not filled.
Step 3: LP supply — still not a DIY purge
- What to look for: Bottles open, pigtail not stripped, regulator not icing, stove or furnace lights. Stove works and Suburban does not = problem at the heater. Nothing LP lights = supply. Auto-stop regulators after a bottle swap can look like a dead water heater.
- Required tools: None on the fittings.
Air after a bottle change can delay ignition. Loosening flares is how bays fill with gas. Do not purge the line yourself.
Step 4: Decode the ignition — pilot vs Phase 3
| Sound / sight | Meaning | Next |
|---|---|---|
| No click at all (DSI) | Switch, 12 V, fuse, ECO, board | Power and ECO |
| Click, no spark | Igniter wire, cracked ceramic, board | Spark test, LP off |
| Spark, no light | Bottles, regulator, solenoid, spider nest | LP, then tech |
| Lights, then off | Flame sense, dirty electrode, ECO, wind | Clean electrode; stop cycling |
| Standing pilot will not hold | Thermocouple, draft, orifice, valve | Pilot path; hire if it will not hold |
- Required tools: Ears at the exterior door. Bottles closed for a spark-only test.
Spark gap is about a business card. Do not bend the electrode into a pretzel. Do not short it to “test the board.”
Step 5: ECO, spiders, and the solenoid
- What to look for: Thermal cutoff / ECO on the tank jacket after a dry fire or overheat. Burner tube full of mud-dauber or spider nests after storage — classic Suburban no-light with a perfect board. Solenoid that clicks at the board but never opens (spark present, LP at the bottle, still no fire).
- Required tools: Visual on the burner with LP off. Solenoid and board replacement are RV-tech jobs.
If electric heat is also dead, fill and try one ECO reset — then stop if it will not latch.
When DIY Ends: Calling a Licensed Pro
Stop at gas-solenoid replacement, a heat-damaged harness, LP odor, a thermal cutoff that will not latch, and any standing-pilot valve work you cannot prove leak-tight. You may fill the tank, set bypass, confirm bottles, and verify spark with fuel off. Suburban DSI boards and valves are model-specific. A mobile RV tech is cheaper than a coach fire from a fifth ignition trial.
Frequently Asked Questions
Q: Why is my Suburban RV water heater not working on gas? A: LP off or starving, a DSI board or igniter fault, a failed solenoid, a thermal cutoff after a dry fire, a burner full of nests, or — on older units — a pilot/thermocouple that will not hold. Electric working only proves the tank can hold water.
Q: Can I fix a Suburban that clicks with no flame myself? A: You can confirm water, 12 V, bottles, and spark with the gas off. Gas-valve and board work is for an RV tech if those pass. Do not keep clicking it.
Q: Suburban gas is dead but electric still works. Is the tank bad? A: No. Gas DSI and the 120-volt element are separate. Stay on the LP/ignition path. A bad tank weeps into the bay; it does not pick one fuel to fail.