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

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RV Water Heater Thermostat and Heating Element Replacement

Parts Needed:

This post contains affiliate links. As an Amazon Associate, I earn from qualifying purchases at no extra cost to you. 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: Safety Preparation and Diagnosis

The calls I get on holiday weekends are always the same energy: a family parked at a campground, kids in the background, and a very stressed adult trying to describe a sound or a symptom over the phone. I always ask the same first question: when did you first notice something was off? The answer is almost never “today.” With Rockwood and Flagstaff water heaters specifically, what usually brings me out is a failed thermostat or a burned-out heating element — two components that rarely blow without warning signs that got ignored for a week or two: lukewarm water on the electric side, a faint burning smell, or a tripped reset button that kept getting pushed back in without anyone asking why it was tripping. Left unaddressed, a failed heating element can put your entire electric system under stress, and a thermostat that’s reading temperature wrong can push water temps into genuinely dangerous territory. I’ve done this repair dozens of times in driveways, campground pull-throughs, and the occasional Walmart parking lot, so what I’m walking you through here isn’t pulled from a manual — it’s exactly what I do when I open that exterior access panel myself.

Step 2: Testing and Removing Failed Components

Test the heating element first to determine if replacement is necessary. With power disconnected and the water heater drained, disconnect one of the power wires from the heating element terminal. Set your digital multimeter to the resistance (ohms) setting. Place one probe on each terminal of the heating element. A functional heating element should show a resistance reading between 8-15 ohms, typically around 10-12 ohms for standard RV water heater elements. If your multimeter displays “OL” (overload) or an infinite reading, the heating element has failed and requires replacement. Any reading significantly outside the 8-15 ohm range also indicates a faulty element. If the heating element tests faulty, proceed with removal. Using an appropriate wrench (typically 1-1/8″ or 1-1/16″ depending on your model), carefully unscrew the heating element from the water heater tank. Turn counterclockwise slowly and steadily. You may notice some residual water drainage when the element begins to loosen – this is normal even after draining the tank. The heating element should come out along with its rubber gasket. Inspect the gasket carefully for deterioration, cracks, or permanent compression. Even if planning to replace the element, keep the old gasket temporarily as a size reference. Examine the element for signs of scale buildup, corrosion, or visible breaks in the element coil, which confirms the need for replacement. Test the thermostat switch to determine if it requires replacement. Locate the two thermostat switches near the top of the water heater assembly – one controls the 12V propane system (wider flat conductor) and one controls the 120V electric system (thinner wire conductor). Focus on the 120V thermostat for electric operation issues. Remove the rubber protective cap covering the reset button. Inspect the wiring connections for any signs of overheating, such as discolored or melted wire insulation, burnt terminals, or loose connections. Disconnect the power wires from the thermostat (typically two wires connected to the bottom terminals). Set your multimeter to continuity or low resistance mode. Place probes on the thermostat terminals – it should show continuity (close to zero ohms) when at normal temperature. If it shows no continuity or if the wiring shows heat damage, replacement is necessary.

Step 3: Installing New Components and Testing

Install the new heating element with proper sealing techniques. Clean the threaded opening in the water heater tank thoroughly, removing any old gasket material, mineral deposits, or corrosion using a clean rag and mild cleaner if needed. Take your new heating element and its accompanying gasket (or purchase a new gasket if not included). Slide the new gasket onto the heating element threads, positioning it against the element’s flange. Carefully thread the heating element into the water heater tank opening by hand, turning clockwise. Hand-tighten as much as possible before using a wrench. Once hand-tight, use your wrench to tighten an additional 1/4 to 1/2 turn – do not overtighten as this can damage the gasket or crack the porcelain lining inside the tank. The element should feel snug and secure with the gasket creating a complete seal. Wire the new heating element following exact specifications. Identify the two terminal posts on the new heating element. Connect the hot (typically black or red) wire from your RV’s electrical system to one terminal and the ground (white or green) wire to the other terminal. Most heating elements are non-polarized, meaning either wire can connect to either terminal. However, always follow the same configuration as the original installation. Use wire nuts or crimp connectors appropriate for outdoor/moisture-exposed applications. Ensure all connections are tight and secure. Wrap each connection with electrical tape for additional protection against moisture. Double-check that no bare wire is exposed and that connections cannot short against the metal water heater housing. If replacing the thermostat, install carefully and reconnect all wiring properly. Remove the old thermostat by disconnecting all wires and removing the mounting screws (typically two screws securing it to the water heater mounting bracket). Position the new thermostat in the exact same location and orientation as the original. Secure it with the mounting screws, ensuring it sits flush against the mounting surface for proper temperature sensing. Reconnect the wires to the new thermostat terminals exactly as they were connected to the old unit – take a photo before disconnecting the old thermostat if you’re unsure of wire positions. The power supply wire (hot) connects to one terminal, and the wire leading to the heating element connects to the other terminal. Ensure all connections are tight and properly insulated. Replace the rubber protective cap over the reset button. Test the entire system thoroughly before returning to normal operation. Close the water heater drain plug securely, tightening it appropriately with your wrench. Turn on the RV’s fresh water supply and open a hot water faucet inside the RV. Allow water to flow until it runs steadily without air bubbles, indicating the tank is completely full and all air has been purged from the system. Close the faucet and inspect the new heating element and all connections for any signs of leakage. Turn on the circuit breaker supplying power to the water heater. Set your digital multimeter to AC voltage mode and carefully test for proper voltage at the heating element terminals – you should read approximately 120 volts (110-125V is normal). Turn on the water heater using the interior control panel switch. Allow 30-45 minutes for a 6-gallon unit or 45-60 minutes for a 10-gallon unit to reach full operating temperature. Test hot water at a faucet to confirm the system is functioning properly. Monitor the first heating cycle to ensure no unusual sounds, smells, or leaks develop.

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