Rockwood/Flagstaff – RV Water Heater Thermostat and Heating Element Replacement

RV Water Heater Thermostat and Heating Element Replacement

Ignore a failing water heater thermostat or heating element long enough, and you’ll be bathing in cold water while the system burns itself out trying to reach a temperature it can’t sense anymore. The stakes aren’t just comfort — a malfunctioning heating element pulling continuous power strains your electrical panel, and a thermostat that’s lost its mind can push water temps into scalding range without shutting down. On Rockwood and Flagstaff units, what usually tips people off is a week or two of lukewarm showers, maybe a burning smell drifting from the exterior panel, or a reset button that keeps tripping and getting shoved back in without anyone stopping to ask why. I’ve tackled this repair in pull-throughs, driveways, and parking lots across forty states, and every time the fix is the same: pull the bad component, test it to confirm the diagnosis, and swap in a new one. This walk-through is real field work, not dealer manual language — it’s what I actually do when I crack open that access panel.

Parts Needed:

• Suburban 232306 Thermostat Switch, Model: 232306, Outdoor&Repair Store (Part Number: 232306) ($18.99)
• Upgraded 520900 RV Water Heater Element For Suburban RV SW Series Electric Wa… (Part Number: 520900) ($17.00)
• Lrichy 110V/120V RV Water Heater Screw-In Electric Heating Element 110V/1400W… (Part Number: Replaces Suburban 520789/520900 • Atwood/Dometic 92249) ($21.97)
• VOTMELL 4 Rolls 1/2 Inch(W) X 520 Inches(L) Teflon Plumbers Tape,Pipe Sealing… ($3.59 ($0.90 / count))
• Nextronics Tool-Free Wire Connectors 25 Pieces – Quick Splice Terminal Blocks… ($8.99 ($0.36 / count))
• Suburban 232767 Water Heater Anode Rod (Part Number: 232767) ($25.99)

When your Rockwood or Flagstaff water heater stops heating on electric mode, the thermostat is the first thing I check — and nine times out of ten, it’s the culprit. I always reach for the Suburban 232306 Thermostat Switch because it’s a direct OEM-spec replacement that drops right in without any wiring gymnastics. Just make sure you drain the tank and let everything cool down completely before you swap it out — burning your fingers on a hot thermostat is a rookie mistake I made exactly once.

If the thermostat checks out fine but you’re still getting cold showers, a burned-out heating element is your next suspect. The Upgraded 520900 RV Water Heater Element for Suburban SW Series is what I keep in my repair kit specifically for Suburban-equipped rigs like the Rockwood and Flagstaff lineup. The upgraded build quality means it handles the hard water and mineral deposits that kill stock elements prematurely. Use a proper element wrench, apply a little thread sealant tape, and torque it snug — don’t overtighten or you’ll crack the tank fitting.

If you’re having trouble sourcing the exact OEM element or just want a solid backup option, the Lrichy 110V/120V 1400W Screw-In Electric Heating Element is a reliable aftermarket alternative worth having on hand. I appreciate that it’s rated at the correct 110V/1400W spec for these units, so you’re not fighting voltage mismatches or slow heating issues down the road. Always verify the thread pitch matches your existing fitting before installation — a quick visual comparison with the old element before you toss it saves a lot of frustration.

Step 1: Testing and Removing Failed Components

Start by verifying the heating element’s condition before you commit to pulling it. Power must stay off and the water heater drained completely. Loosen one of the power terminals connected to the heating element and disconnect the wire. Switch your digital multimeter to ohms (resistance). Touch each probe to one of the heating element’s two terminals. A good element reads between 8–15 ohms, usually landing right around 10–12 ohms on a standard RV unit. If your meter displays “OL” (overload) or infinity, the element is dead. Any reading that falls way outside that 8–15 ohm window also means replacement is your only option.

Once you’ve confirmed the element is bad, remove it from the tank. Grab a wrench sized to fit the element’s hex nut — usually 1-1/8″ or 1-1/16″ depending on your specific model — and turn counterclockwise with steady, controlled pressure. Expect a little water to dribble out as the seal breaks, which is completely normal even after draining. The element slides out along with its rubber gasket. Before you throw anything away, look hard at that gasket: cracks, permanent compression, or crumbling rubber means it’s done. Keep the old one as a reference for size if you need it. Look over the element itself too — scale buildup, rust, or visible breaks in the heating coil all confirm you made the right call replacing it.

Test the thermostat switch next to see if it’s also shot. Two thermostat switches sit near the top of the water heater assembly — the wider, flat one controls the 12V propane side, and the thinner wire one handles the 120V electric side. For electric heating problems, focus on the 120V unit. Pull off the rubber cap that sits over the reset button. Look closely at the wire connections for discolored insulation, melted plastic, charred terminals, or wires that have worked loose. These are signs the switch got too hot and failed. Disconnect both power wires from the thermostat’s bottom terminals. Set your multimeter to continuity mode or its lowest resistance setting.

Press the probes against the thermostat’s two terminals. A working thermostat shows continuity — a reading very close to zero ohms. No continuity reading, or any evidence of heat damage to the wires and terminals, means the thermostat needs to come out.

Step 2: Installing New Components and Testing

Prep the tank opening for the new heating element by cleaning out the threads thoroughly. Wipe away old gasket material, mineral scale, and any corrosion with a clean rag and mild cleaner if needed. Grab your new heating element and its fresh gasket (or source a new gasket separately if it didn’t come with one). Slide the gasket onto the element’s threads so it sits snug against the element’s flange. By hand, thread the element into the tank opening, turning clockwise, and get it as tight as you can without tools. Once your fingers won’t turn it anymore, use your wrench and snug it down another 1/4 to 1/2 turn — no more. Overtightening strips the threads or cracks the interior tank lining.

Connect power to the new heating element the same way the old one was wired. The heating element has two terminal posts. The hot wire (usually black or red) goes to one terminal, and the ground (usually white or green) goes to the other. Most RV heating elements don’t care which wire goes where, but follow your original setup just to keep things consistent. Use wire nuts or crimp connectors rated for outdoor and damp conditions. Make sure every connection is pulled tight. Wrap electrical tape around each terminal connection for extra moisture protection. Step back and confirm no bare copper is visible and nothing can accidentally touch the metal water heater housing and short out.

If the thermostat also needs replacing, pull the old one out by disconnecting its wires and unscrewing the two mounting bolts that hold it to the bracket. Put the new thermostat in the exact same spot and angle as the original — this matters for temperature sensing accuracy. Bolt it down snug and flush. Reconnect the wires the same way they went on the old switch: the power supply (hot) wire to one terminal and the wire that runs to the heating element to the other. If you’re not 100% certain, snap a photo of the original before you disconnect anything. Make sure all connections are tight and covered with insulation. Slide the rubber protective cap back over the reset button.

Test the system completely before you call the job done. Tighten the drain plug at the tank bottom securely. Turn on your RV’s fresh water pump and crack open a hot water faucet inside. Let water run until it flows steadily without air bubbles — that means the tank is full and you’ve bled the lines. Shut that faucet and inspect the new element and all your wire connections for any drips or leaks. Flip the circuit breaker that feeds the water heater back on. Put your multimeter on AC voltage and probe the heating element’s terminals — you should see approximately 120 volts (110–125V is acceptable). Switch the water heater on using the interior control panel. Give a 6-gallon unit 30–45 minutes to reach full temp, or 45–60 minutes for a 10-gallon model. Run hot water at a faucet to confirm everything’s heating properly. Keep an eye on the first heating cycle for any odd noises, smells, or unexpected leaks.

The Suburban 232306 Thermostat Switch That Actually Cuts Power When It’s Supposed To

On Rockwood and Flagstaff rigs, the thermostat switch is the gatekeeper between a tank full of hot water and one that won’t heat past lukewarm — when it fails, the heating element keeps cycling without ever reaching setpoint, or worse, the tank won’t heat at all. This is the OEM part that stops the guessing game.

What works

• Direct OEM replacement means no cross-compatibility headaches — the mounting threads and electrical connectors line up on the first try.
• Thermostat actually stops the heating element when the tank hits your set temperature instead of letting it run constantly and trigger the high-limit cutoff.
• Once installed, you’ll hear the relay click when the element cycles on and off — that’s the sound of a system that’s working as designed, not fighting itself.

What doesn’t

• You have to drain the water heater completely and get a good wrench on the old thermostat body — if it’s corroded in, you’re looking at 20+ minutes of fighting it, not a quick swap.
• If your heating element is also bad (common failure pair), replacing the thermostat alone won’t fix the problem — you’ll discover this mid-repair and have to order the element separately and bleed the system twice.

I’ve had the thermostat test as OK on a multimeter but still refuse to cut power at the right temperature — you start second-guessing whether it’s really the switch or something downstream in the wiring — and it turned out to be the switch all along. Get the Suburban 232306 thermostat here.

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