Keystone Montana – 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 a bad thermostat is one of the sneakiest culprits behind a water heater that just won’t perform — and when it comes to the Keystone Montana’s Suburban unit, you don’t want to gamble with a generic part. The Suburban 232306 Thermostat Switch is the OEM-spec replacement, which means it snaps in without any wiring gymnastics. One installation tip: let the water heater cool completely before you touch it, and double-check that the reset button seats firmly after swapping it out.

I keep a spare heating element in my repair kit specifically because this is one of those failures that always seems to happen on a Friday night in a remote campground. The Upgraded 520900 RV Water Heater Element for Suburban SW Series is purpose-built for these units and threads in cleanly without overtightening drama. The upgraded build quality over the stock element is a real selling point — I’ve seen the original elements corrode faster than they should, especially in areas with hard water. Wrap those threads with Teflon tape and torque it snug, not gorilla-tight.

If you’re looking for a budget-friendly backup or want a second element on hand before you start the job, the Lrichy 110V/120V 1400W Screw-In RV Water Heater Element is worth having in your toolkit. It’s a solid aftermarket option that matches the voltage and wattage specs your Suburban heater needs, and the screw-in design makes the swap straightforward even in a tight compartment. Just confirm your heater is wired for 110V before you order, and always shut off the breaker and drain the tank before pulling the old element out.

Step 1: Safety Preparation and Diagnosis

I pull up to broken rigs for a living, and I can tell you without hesitation which repairs show up on my schedule over and over — not because RVs are poorly built across the board, but because a handful of systems get neglected in exactly the same ways by exactly the same owners. Water heaters are near the top of that list, and on Keystone Montanas specifically, I’ve replaced more thermostats and heating elements than I can count. The failure pattern is almost always the same: the electric element quietly burns out or the thermostat trips and never gets reset, the owner assumes the whole unit is shot, and suddenly a straightforward two-part fix turns into an expensive service call that didn’t need to happen. What’s at stake here isn’t just comfort — a water heater that’s limping along with a failing thermostat can overheat, trip breakers repeatedly, or leave you with cold showers in a campground three states from the nearest dealer. I’ve put this guide together from real field experience so you can diagnose the problem correctly the first time and make the repair confidently, whether you’re doing it yourself or just want to understand what you’re paying someone like me to do.

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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