Keystone Montana – RV Water Heater Thermostat and Heating Element Replacement

RV Water Heater Thermostat and Heating Element Replacement

Most Keystone Montana owners will ignore their water heater until it stops working, and by then they’ve already made the problem worse. Here’s what actually happens: the heating element corrodes silently, or the thermostat drifts so far out of calibration that it either locks the element on permanently or stops triggering it at all. The owner panics, assumes the tank itself is dead, and books a $300+ service call that could’ve been a $40 parts swap and a weekend afternoon. I’ve replaced more of these thermostats and elements on Montanas than any other single repair, and the reason isn’t design—it’s that nobody diagnoses before they call for help. What gets overlooked is that these two failures look identical from the outside: no hot water. But one kills your heating element through constant cycling, and the other just means the switch quit talking to it. This guide walks you through testing which one actually failed, then swapping it out correctly so you’re not guessing or throwing parts at the problem.

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)

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: Testing and Removing Failed Components

Start by isolating which part failed. Power off the water heater completely and drain the tank. Disconnect one of the power wires from the heating element terminal. Switch your digital multimeter to the resistance (ohms) mode. Touch one probe to each of the heating element’s two terminals. A healthy element reads between 8–15 ohms, typically hovering around 10–12 ohms on standard RV units. If the meter displays “OL” (overload) or refuses to settle on a number, the element has burned open. Any reading that lands well outside that 8–15 range also means it’s shot and needs replacing.

When the element tests bad, it’s time to remove it. Grab a wrench sized for your model (usually 1-1/8″ or 1-1/16″), position it on the element’s hex nut, and turn counterclockwise with steady, even pressure. Don’t rush this—you’ll feel some water dribble out as it loosens, even after you’ve drained the tank. That’s completely normal. The element will slide out with its rubber gasket attached. Pull that gasket off and examine it closely: look for splits, hard spots where it’s been compressed permanently, or visible decay. Hold onto it as a sizing reference, even if you’re tossing it. Look at the element itself too—scale buildup, rust stains, or a visibly snapped heating coil all confirm you need a replacement.

Now test the thermostat to see if it’s the culprit instead. Locate the two thermostat switches sitting near the top of the water heater—one switch is fatter with a wider conductor and handles the 12V propane circuit; the other is thinner-wired and controls the 120V electric side. You’re concerned with the electric thermostat for now. Pop off the rubber cap that covers the reset button. Look at the wire connections underneath: any browning, melting, scorched terminals, or obviously loose wires point to heat damage. Carefully disconnect the two power wires from the thermostat’s bottom terminals. Flip your multimeter to continuity or resistance mode.

Place one probe on each thermostat terminal. At room temperature, continuity should read near zero ohms—basically a closed switch. If you get no continuity or the wires show heat damage, the thermostat is dead and needs replacement.

Step 2: Installing New Components and Testing

Fit the replacement heating element using proper sealing. Wipe down the threaded opening inside the water heater tank with a dry rag, scrubbing away any leftover gasket material, mineral deposits, or corrosion—use a bit of mild solvent if the buildup is stubborn. Slide the new gasket onto the heating element’s threads, pushing it flush against the element’s flange. Begin threading the new element into the tank opening by hand, turning clockwise, and hand-tighten it as far as you can without tools. Once it’s tight by hand, use your wrench to crank another 1/4 to 1/2 turn and stop—over-tightening crushes the gasket and can crack the tank’s internal porcelain coating.

Wire the new heating element according to spec. The element has two terminal posts. Connect the hot wire (usually black or red) from your RV’s electrical system to one post and the ground wire (white or green) to the other. Most heating elements aren’t polarized, so either wire can go either way, but stick with whatever configuration the original installation used. Use wire nuts or crimp connectors rated for damp outdoor environments. Crank every connection tight. Wrap electrical tape around each connection for extra moisture protection, and verify that no copper is showing and nothing can short out against the heater housing.

If you’re also swapping the thermostat, pull it out carefully. Disconnect all the wires and remove the mounting screws (usually two bolts that hold it to the bracket). Set the new thermostat in the exact same spot and angle so it can sense temperature properly. Bolt it down flush. Reconnect each wire exactly where it came from on the old unit—snap a quick photo of the old thermostat before you disconnect it if you’re not certain. One wire (the power supply) goes to one terminal; the other wire (the one running to the element) goes to the other. Make connections tight and insulated. Screw the rubber protective cap back over the reset button.

Time to test the repair. Tighten the drain plug on the water heater tank with your wrench. Open your RV’s main fresh water supply and turn on a hot water faucet inside—let the water run until it flows smoothly without sputtering air bubbles, which signals the tank is full and bled of air. Shut the faucet. Inspect the new element and all connections for drips or spray. Flip the circuit breaker back on for the water heater. Set your multimeter to AC voltage and probe the two terminals of the heating element—you should see roughly 120 volts (anywhere from 110–125V is fine). Engage the water heater on the interior control panel. Give a 6-gallon unit 30–45 minutes or a 10-gallon unit 45–60 minutes to heat to temperature. Run hot water at a sink to verify it’s working. Watch the first heat cycle for strange noises, weird smells, or leaks.

The Suburban 232306 Thermostat That Actually Holds Temperature on Montanas

The Suburban water heater thermostat is the most common failure point on Keystone Montanas—the heating element runs constantly, the water gets scalding, or it won’t heat at all. This switch controls the entire heating cycle, and when it drifts out of calibration, you’re either freezing or boiling.

What works

• Direct replacement with no modification—pinout matches exactly, slides into the original location without adapters or fabrication.
• Water temperature stays stable where you dial it instead of swinging 20+ degrees in either direction, which eliminates scalding surprises and cold shocks mid-shower.
• The heating element cycles on and off as intended rather than running in marathon sessions until the safety cutout trips, which noticeably drops your 12V parasitic draw and propane burn rate.

What doesn’t

• Some aftermarket units sit in warehouses long enough for the terminals to oxidize—check the contacts when it arrives and polish them with fine sandpaper if needed.
• This replaces the thermostat only; if your heating element is burned out (no voltage showing at the element terminals), you’re buying the element replacement as a separate job, and most people skip that diagnostic step.

I’ve had this thermostat get to the job site and still doubt whether I pulled the old one correctly, so I always ohm-test both the old and new before reinstalling—caught a bad replacement unit once that way and saved an hour of troubleshooting. Order the Suburban 232306 here.

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