Thor Water Heater Dead? Read the Door Badge
The Short Answer: Thor Motor Coach does not build a “Thor” water heater. Four Winds, Chateau, ACE, Quantum, Hurricane, and cousins ship Suburban, Atwood/Dometic, Truma, or another tankless behind a Thor wall. Open the exterior door, read the badge, then follow that product. Smell propane, shut the bottles. Do not invent an OEM tank.
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Search Intent & The Real Problem
The sticker inside the coach says Thor. The shower is cold. Search results keep inventing a Thor-branded 6-gallon. I have never installed one. I have replaced Suburban SW6DE / SW10DE / SW16DE Phase 3 units, Atwood GC-series DSI tanks, and the occasional Truma AquaGo or Girard/Furrion tankless in the same bays. Wrong board, wrong electrode, melted harness. Start at the door badge, not the coach brand.
What other guides get wrong
They write a “Thor water heater troubleshooting” ritual as if Thor stamped a unique tank. They mix Suburban Phase 3 boards with Atwood/Dometic boards. They send you after a standing-pilot thermocouple on a DSI heater that has none. They skip bypass valves, so a winterized tank gets a new board.
Step-by-Step Troubleshooting
Step 1: Open the door. Read the badge. There is no Thor OEM.
| Door badge / what you see | What it actually is | Go here |
|---|---|---|
| Suburban, Phase 3, SW6DE / SW10DE / SW16DE | DSI tank, dual-fuel common | Suburban gas, Phase 3, SW10DE, igniter |
| Atwood or Dometic | DSI tank | Atwood clicking, Atwood electric |
| Truma AquaGo | RV tankless | Truma AquaGo |
| Girard, Furrion, other on-demand | RV tankless, not a 6-gallon | Tankless tech — not a Suburban board |
| Standing pilot, push-button piezo | Older tank | Piezo won’t spark |
| No heater in the bay, wall unit only | Tankless or off-board | Follow that jacket, not this table |
- What to look for: Model sticker on the interior of the access door or the tank jacket. Photograph it. Four Winds / Chateau / ACE on the coach skin does not pick the part.
- Required tools: Flashlight, phone camera.
Step 2: Water in the tank, bypass in normal, which fuel is dead
- What to look for: Three-valve bypass in the heat path, not winterize. Steady stream at a hot faucet, no sputter. A winterized tank is empty even if the lines are wet. Dual-fuel tanks: electric switch off while you diagnose gas so you do not dry-fire a ~1400 W / ~12 A element on a 10-gallon.
| What works | Look at first |
|---|---|
| Electric OK, gas dead | LP, DSI/pilot, igniter, solenoid, ECO |
| Gas OK, electric dead | 120 V, ECO, element |
| Both dead | Empty tank, bypass, winterized, or no 12 V and no LP |
| Tankless: no tank | 12 V, LP, water filter, freeze lock |
- Required tools: Cabinet diagram, a hot faucet.
Do not spark a DSI on a tank you have not filled. ECO after a dry fire will kill gas, electric, or both.
Step 3: 12-volt, LP, and the click — still not a DIY purge
- What to look for: Coach battery / converter. DSI boards get stupid under ~10.5 V; rest voltage ~12.6 V is the baseline. Bottles open, pigtail not stripped, regulator not icing, stove or furnace lights. Stove works and the water heater does not = problem at the heater. Nothing LP lights = supply. Auto-stop regulators after a bottle swap mimic a dead heater.
- Required tools: None on the flares. A DC meter if you are qualified.
Air after a bottle change can delay ignition. Loosening flares is how bays fill with gas.
Step 4: Decode ignition on that product
| Sound / sight | Meaning | Next |
|---|---|---|
| No click at all (DSI) | Switch, 12 V, fuse, ECO, board | Power and ECO — Suburban reset |
| Click, no spark at the tip | Cracked ceramic, burned lead, board | Spark test, bottles closed |
| Spark, no flame | Bottles, regulator, solenoid, spider nest | Fuel path; electrode is fine |
| Lights, then drops | Dirty rod, gap, flame sense, ECO | Clean/regap or stop cycling |
| Tankless fan, then lockout | That brand’s code | Truma / Girard path, not a thermocouple |
- What to look for: Spark gap about 1/8” (3 mm). Do not short the electrode “to test the board.” Do not mix a Suburban 232307-class electrode with an Atwood rod.
- Required tools: Ears at the exterior door. Bottles closed for a spark-only look.
Step 5: Electric half, ECO, and when the tank is actually dead
- What to look for: Shore power or generator actually on the coach. ECO on the tank jacket after a dry fire or overheat — fill, one reset, stop if it will not latch. A wet bay or rusty tank skin is a vessel, not a board. Tankless units do not have a “Thor anode.”
- Required tools: 120 V confirmed dead before you open a box. Licensed RV tech for element, solenoid, and board swaps you cannot match.
When DIY Ends: Calling a Licensed Pro
Stop at a propane smell, a heat-damaged harness, gas-solenoid replacement, a board you cannot match to the door badge, an ECO that will not latch, and any delayed-ignition bang. You may fill the tank, set bypass, confirm bottles and 12 V, and spark-test with fuel off. You may not loosen LP fittings or keep clicking a flooded burner. A mobile RV tech who stocks Suburban and Dometic is cheaper than a coach fire from a fifth trial — and cheaper than a “Thor” part that does not exist.
Frequently Asked Questions
Q: Why is my Thor water heater not working? A: Thor did not make the heater. Read the exterior-door badge. Suburban, Atwood/Dometic, Truma, or another tankless fail on LP, DSI/igniter, ECO, bypass, or 12 V — not on a Thor-branded tank.
Q: Is there a Thor OEM water heater I should order? A: No. Order Suburban, Dometic/Atwood, Truma, or the tankless on the rating plate. A “Thor water heater” listing is a listing.
Q: Gas is dead but electric still works in my Thor. Is the tank bad? A: No. On dual-fuel Suburban and Atwood tanks those are separate circuits. Electric working means the tank can hold water. Stay on the LP/ignition path.