KZ Durango – 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. After years on the road, I’ve learned that the thermostat is almost always the first thing to fail on a Suburban water heater — and using anything other than an OEM replacement is a gamble I’m not willing to take. The Suburban 232306 Thermostat Switch is a direct factory replacement, which means no adapting, no splicing, and no second-guessing the wiring. It snaps in clean and calibrates correctly right out of the box — something knockoffs consistently fail to do.

I keep a spare heating element in my repair kit specifically because this failure always seems to happen when you’re three days from the nearest RV parts store. The Upgraded 520900 RV Water Heater Element for Suburban SW Series is built to match the original specs exactly, but with upgraded materials that hold up better against the mineral deposits and sediment buildup that kill stock elements prematurely. Just make sure you drain the tank fully and use a proper element wrench — rushing that step is how people crack the tank threads.

If you’re doing this repair on a tighter budget or your original element is no longer available, the Lrichy 110V/120V Screw-In Electric Heating Element is a solid universal option worth considering. At 1400W and designed specifically for RV water heater applications, it delivers reliable performance without the premium price tag. One thing I’ll flag from experience — confirm your thread size before installation and apply fresh PTFE tape to the threads every single time, no exceptions, or you’re just creating your next leak to chase down the highway.

Step 1: Safety Preparation and Diagnosis

Some repairs on an RV are DIY-friendly. Others involve propane, 120-volt shore power, or structural load-bearing components where a mistake has real consequences. Part of my job is knowing which category a job falls into — and being honest with owners about the line between a competent DIY fix and one that needs a professional on site. A water heater thermostat or heating element replacement on a KZ Durango sits right on that line — it’s absolutely a job a mechanically confident owner can handle, but only if they understand that this repair touches both a propane system and a 120-volt electrical circuit simultaneously, which means a skipped step isn’t just an inconvenience, it’s a potential fire or electrocution hazard. I’ve shown up to rigs where someone got 90% of the job right, and that other 10% — a loose terminal connection, a drain plug reinstalled without thread sealant, a thermostat reset button that was bypassed instead of investigated — turned a routine fix into a much bigger problem. If you work through this guide carefully and respect the safety steps, this is a repair you can get done in a driveway in a few hours; if anything here feels outside your comfort level, stop and call someone — there’s no shame in it, and I’d rather you make that call than the other one.

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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