How To Install A Tankless Water Heater In An RV

There’s nothing quite like the freedom of RV life, but let’s be honest, the struggle for a decent hot shower can quickly dim that adventurous spirit. Traditional RV water heaters, with their bulky tanks and limited capacity, often leave you rushing or rationing precious hot water. If you’ve ever shivered through a quick rinse or waited impatiently for the tank to reheat, you know the feeling.

Imagine this instead: stepping into your RV shower, turning on the faucet, and enjoying a continuous stream of hot water, just like at home. No more watching the clock, no more lukewarm surprises. This isn’t a pipe dream; it’s the reality a tankless water heater can bring to your mobile adventures.

At OutwardLab, we believe in living outdoors smarter. That’s why we’ve put together this comprehensive guide on how to install a tankless water heater in an RV. We’ll walk you through everything, from understanding the benefits and choosing the right unit to a detailed, step-by-step installation process and essential maintenance tips. By the end, you’ll have the confidence and knowledge to upgrade your RV’s hot water system, ensuring comfort and convenience wherever your journey takes you.

Let’s dive in and transform your RV showering experience!

Table of Contents

Why Go Tankless? The Benefits for Your RV Lifestyle

Upgrading to a tankless water heater in your RV offers a multitude of advantages that go beyond just having hot water. It’s about enhancing your overall outdoor living experience, making it more comfortable, efficient, and even more sustainable.

Space Saving

Traditional RV water heaters come with a large, insulated tank that takes up valuable storage space. A tankless unit is significantly smaller and often lighter. This frees up crucial real estate inside or outside your RV, allowing for more storage or a less cluttered aesthetic.

Endless Hot Water

This is arguably the biggest draw. A tankless system heats water on demand, meaning it doesn’t run out. You can enjoy long, relaxing showers, wash dishes without interruption, and never worry about the next person in line getting a cold surprise. This truly transforms the comfort of your RV.

Energy Efficiency & Sustainability

Tankless heaters only consume energy when hot water is being used. Unlike traditional tanks that constantly heat and reheat a reservoir of water, tankless units avoid standby heat loss. This makes them a more sustainable and eco-friendly choice, reducing your propane or electrical consumption and your environmental footprint.

Weight Reduction

A full 6-gallon RV water heater tank can add over 50 pounds to your rig, and a 10-gallon tank even more. Removing this weight, especially when dry camping, can contribute to better fuel economy and allow you to carry other essentials. Every pound counts when you’re maximizing your RV’s capacity.

Choosing the Right Tankless Water Heater for Your RV

Before you jump into the installation process, selecting the appropriate tankless water heater is crucial. Not all units are created equal, especially when it comes to the unique demands of RV life.

Propane vs. Electric

Most RV tankless water heaters are propane-fired. Propane units generally offer higher flow rates (Gallons Per Minute or GPM) and don’t require a substantial electrical hookup. Electric tankless heaters, while available, typically demand a significant amount of amperage, which can be challenging for standard RV electrical systems unless you have a robust shore power connection or a powerful generator.

Sizing and GPM (Gallons Per Minute)

The GPM rating tells you how much hot water the unit can produce per minute at a given temperature rise. For RV use, a unit producing 1.5 to 2.5 GPM is usually sufficient for one shower at a time. If you envision running two hot water fixtures simultaneously (e.g., shower and sink), you’ll need a higher GPM rating. Consider your typical water usage patterns.

RV-Specific Models

Look for tankless water heaters specifically designed for RVs. These units are built to withstand road vibrations, often have smaller footprints, and are designed for easier integration into existing RV plumbing and venting systems. Brands like Girard, Furrion, and Truma are popular choices in the RV market.

Venting Requirements

Tankless water heaters, especially propane models, require proper venting to expel combustion gases safely. RV-specific units come with integrated venting systems designed to fit into standard RV water heater cutouts or provide clear instructions for creating new vents. Always ensure the unit’s venting requirements match your RV’s capabilities and safety standards.

Essential Tools and Materials for Your Tankless Water Heater Installation

Having the right tools and materials on hand will make the installation process smoother and safer. Don’t start until you’ve gathered everything on this list.

Safety First Gear

Safety Glasses: Protect your eyes from debris, water, or chemicals.
Work Gloves: Protect your hands.
First Aid Kit: Always keep one handy for any minor scrapes or cuts.

Plumbing Tools

Adjustable Wrenches: For loosening and tightening water line connections.
Pipe Cutters: If you need to modify existing PEX or copper lines.
PEX Crimping Tool & Crimp Rings: If your RV uses PEX and you need to make new connections.
Thread Seal Tape (Teflon Tape): For sealing threaded plumbing connections.
Bucket & Towels: To catch any residual water when disconnecting lines.

Electrical Tools (if applicable for ignition/power)

Screwdrivers (Phillips and Flathead): For access panels and wiring terminals.
Wire Strippers/Cutters: For making electrical connections.
Voltmeter/Multimeter: To test electrical connections and ensure power is off.
Electrical Tape: For insulating connections.

Mounting Hardware

Drill & Drill Bits: For mounting the unit and creating pilot holes.
Jigsaw or Reciprocating Saw: If you need to modify the cutout size.
Measuring Tape & Pencil: For accurate measurements.
Level: To ensure the unit is installed straight.
Sealant (RV-grade, non-sagging butyl caulk or silicone): For sealing around the exterior flange.
Mounting Screws: Often come with the unit, but have extras on hand.

Miscellaneous

Shop Vacuum: For cleaning up debris.
Flashlight or Headlamp: For working in dimly lit areas.
Rag/Sponge: For cleanup.

A Step-by-Step Guide: How to Install a Tankless Water Heater in an RV

This section provides a detailed, actionable how to install a tankless water heater in an RV guide. Always refer to your specific unit’s manual, as steps may vary slightly. Safety is paramount; if you’re unsure, consult a professional.

Step 1: Prepare Your RV and Gather Supplies

Before you begin, ensure your RV is safe and ready for the upgrade.

Turn off Power: Disconnect shore power, turn off the inverter, and disconnect your RV’s 12V battery.
Shut Off Propane: Close the main valve on your propane tank.
Drain Water System: Open all hot and cold faucets, flush the toilet, and open the low-point drains to completely drain the freshwater system. This prevents water spills during removal.
Gather Tools: Ensure all the tools and materials listed above are within reach.

Step 2: Disconnect and Remove the Old Water Heater

This is where the real work begins. Be prepared for some water to come out.

Access the Heater: Open the exterior access panel of your old RV water heater.
Disconnect Electrical: Carefully disconnect any 12V wiring (for ignition/control) and 120V wiring (if it’s an electric/gas model). Use your multimeter to confirm no power is present.
Disconnect Propane: With a wrench, carefully loosen and disconnect the propane line. Expect a slight hiss as residual gas escapes. Cap the line temporarily to prevent debris entry.
Disconnect Water Lines: Locate the hot water outlet, cold water inlet, and pressure relief valve (T&P valve) lines. Place a bucket underneath and disconnect these lines. Be ready for water to drain.
Remove Mounting Screws: Unscrew the mounting screws or bolts that secure the old water heater to the RV frame from both the interior and exterior.
Extract Old Unit: Carefully slide the old water heater out of its opening. This might require some wiggling.
Clean the Area: Thoroughly clean the cutout opening and surrounding area, removing any old sealant, debris, or rust.

Step 3: Prepare the Opening and Mounting Area

Your new tankless unit might have a different size or shape.

Measure & Adjust: Compare the dimensions of your new tankless unit to the existing cutout. Most RV tankless heaters are designed to fit standard cutouts, but some may require slight modifications.
Cut if Needed: If modifications are necessary, carefully use a jigsaw or reciprocating saw to enlarge the opening. Always measure twice and cut once. Ensure the opening is square and clean.
Test Fit: Briefly place the new tankless unit into the opening to ensure it fits snugly and flush against the exterior wall. Check that interior mounting points align.

Step 4: Install the New Tankless Unit

Carefully slide the new unit into place.

Apply Sealant: Apply a generous bead of RV-grade, non-sagging butyl caulk or silicone sealant around the perimeter of the exterior flange of the tankless heater. This creates a watertight seal.
Slide In: Gently slide the tankless water heater into the prepared opening from the exterior.
Secure Mount: From the interior, secure the unit with the provided mounting screws or bolts. Ensure it’s level and tightly affixed to the RV’s structure.

Step 5: Connect Water Lines

This is a critical step for preventing leaks.

Identify In/Out: Locate the cold water inlet and hot water outlet on your new tankless unit. They are usually clearly marked.
Connect Cold Water: Connect the RV’s cold water supply line to the tankless heater’s cold water inlet. Use thread seal tape on all threaded connections.
Connect Hot Water: Connect the RV’s hot water distribution line to the tankless heater’s hot water outlet. Again, use thread seal tape.
Check for Leaks (Initial): Once connected, turn on your RV’s freshwater pump or city water connection (slowly) and check all new water connections for immediate leaks. Tighten any weeping connections.

Step 6: Connect Fuel/Electrical Lines

Follow the manufacturer’s instructions precisely for these connections.

Connect Propane (if applicable): Connect the RV’s propane supply line to the tankless heater’s propane inlet. Use a gas-rated thread sealant or tape, and ensure the connection is tight.
Connect Electrical: Connect the 12V DC wiring for the unit’s control board and igniter. Match positive to positive and negative to negative, ensuring secure connections. Some units may require a dedicated fuse.

Step 7: Test the System and Check for Leaks

This is where you bring everything to life.

Ventilation Check: Ensure the exterior vent is clear and unobstructed.
Turn on Propane: Slowly open the main valve on your RV’s propane tank.
Restore Power: Reconnect your RV’s 12V battery and shore power (if applicable).
Purge Air: Open a hot water faucet inside the RV. Let the water run until all air is purged from the lines and a steady stream of cold water comes out.
Test Hot Water: Turn on the tankless water heater (if it has a separate switch) and then open a hot water faucet. The unit should ignite and begin heating water. Observe the water temperature.
Leak Detection: While the system is running, carefully inspect all plumbing and propane connections for any leaks. For propane, you can use a leak detection solution (soapy water) which will bubble if there’s a leak. Address any leaks immediately.

Step 8: Secure and Seal

The final touches ensure longevity and weather protection.

Exterior Seal: Re-inspect the exterior sealant around the unit’s flange. Add more if needed, ensuring a complete, watertight seal against the elements.
Interior Panels: Replace any interior access panels or trim you removed.
Clean Up: Clean up your workspace, dispose of old parts responsibly, and admire your handiwork!

Common Problems and Troubleshooting Tips After Installation

Even with careful installation, you might encounter minor issues. Here are some common problems with how to install a tankless water heater in an RV and how to troubleshoot them.

No Hot Water or Inconsistent Temperature

This is the most frustrating issue. Start by checking the basics.

Water Flow: Tankless heaters require a minimum water flow to activate. Ensure your RV’s water pump is on and functioning correctly, or that city water pressure is adequate.
Propane Supply: Check your propane tank level and ensure the valve is fully open. Listen for the igniter clicking.
Air in Lines: Air pockets can prevent proper operation. Purge all hot water lines again by running faucets until flow is consistent.
Temperature Settings: Verify the temperature setting on the unit’s control panel.
Blocked Vent: Ensure the exterior vent is clear of debris.

Low Water Pressure

If your overall water pressure has dropped, it might be related to the installation.

Kinked Lines: Check all newly installed water lines for kinks or bends that restrict flow.
Sediment Filter: Some tankless units have an inlet sediment filter. Check if it’s clogged.
Shower Head: Your existing low-flow RV shower head might be too restrictive for the tankless unit to consistently activate. Consider upgrading to a higher-flow RV shower head.

Error Codes

Modern tankless units often display error codes on their control panels.

Consult Manual: Always refer to your unit’s specific owner’s manual for error code definitions and troubleshooting steps.
Common Codes: Common codes relate to ignition failure, flame loss, or flow sensor issues. These often point back to propane supply, water flow, or electrical connections.

Pilot Light Issues (Propane Units)

Some older or simpler propane units might have a pilot light.

Relight: Follow the manufacturer’s instructions for relighting the pilot.
Thermocouple: If the pilot won’t stay lit, the thermocouple might be faulty or dirty. This is often a job for a professional.

Maintaining Your RV Tankless Water Heater: Best Practices for Longevity

Proper maintenance is key to ensuring your new tankless water heater provides reliable, endless hot water for years to come. Follow these how to install a tankless water heater in an rv best practices and care guide tips.

Regular Descaling

Mineral deposits (limescale) can build up inside the heat exchanger, reducing efficiency and flow. This is a crucial part of your how to install a tankless water heater in an rv care guide.

Frequency: Descale your unit annually, or more frequently if you often fill your RV with hard water.
Process: This typically involves circulating a descaling solution (like white vinegar or a commercial descaler) through the unit’s water lines. Many units have dedicated ports for this. Follow your manufacturer’s instructions carefully.

Winterization

Just like your RV’s entire plumbing system, your tankless water heater needs to be properly winterized to prevent freeze damage.

Drain Thoroughly: Ensure all water is completely drained from the unit. Some models have a specific drain plug.
Bypass (if applicable): If your RV has a water heater bypass, use it.
Antifreeze: If using RV antifreeze, ensure it flows through the tankless unit’s internal lines to protect against freezing.

Venting Maintenance

Keep the exterior vent clear and free from obstructions.

Inspect Regularly: Periodically check for insect nests, leaves, or other debris that could block the exhaust or intake vents.
Clean Gently: Use a soft brush or compressed air to clear any blockages.

Checking Connections

Road vibrations can sometimes loosen connections over time.

Visual Inspection: Annually or semi-annually, visually inspect all water, propane, and electrical connections.
Tighten as Needed: Gently tighten any connections that appear loose, but do not overtighten. For propane connections, use a leak detector solution after tightening.

Frequently Asked Questions About RV Tankless Water Heaters

How long does it take to install a tankless water heater in an RV?

For someone with basic DIY skills and the right tools, replacing an existing tank-style water heater with a tankless unit can typically take 4-8 hours. If modifications to the cutout or significant plumbing/electrical work are needed, it could take longer. First-timers should allocate a full day.

Do tankless water heaters work with low RV water pressure?

Tankless water heaters require a minimum flow rate (GPM) to activate and maintain heat. While many RV-specific models are designed to operate at lower pressures than residential units, extremely low pressure from a weak pump or city water connection might prevent them from working optimally. Some units have flow sensors that will prevent ignition if the flow is too low.

Can I install a tankless water heater myself, or should I hire a professional?

If you are comfortable with basic plumbing, electrical work, and working with propane, installing an RV tankless water heater is a manageable DIY project. However, working with propane and electrical systems carries inherent risks. If you are unsure at any point, or uncomfortable with any step, it’s always best to consult or hire a certified RV technician or plumber to ensure safety and proper installation.

What’s the average lifespan of an RV tankless water heater?

With proper installation and regular maintenance, an RV tankless water heater can last 10-20 years. This is generally longer than traditional tank-style water heaters, which often last 6-10 years. Descaling and winterization are crucial for extending its lifespan.

Are tankless water heaters more expensive to run in an RV?

Generally, no. While the initial purchase cost of a tankless unit can be higher, they are more energy-efficient in the long run. They only heat water on demand, eliminating standby heat loss from a constantly heated tank. This typically results in lower propane or electrical consumption, saving you money on fuel over time, especially if you take frequent showers or use hot water often.

Upgrading your RV with a tankless water heater is a significant step toward making your outdoor adventures more comfortable and convenient. By following this detailed guide, you’ve gained the knowledge to confidently tackle this project, transforming your RV’s hot water experience from rationing to endless luxury.

Remember, safety first! Always double-check your connections, test thoroughly, and don’t hesitate to seek professional help if you encounter challenges beyond your comfort level. With your new tankless system, you’re not just installing a piece of equipment; you’re investing in boundless comfort on the open road.

Now, go forth and enjoy those long, hot showers wherever your journey takes you. Stay safe and stay comfortable!

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Eric James

Hi, I'm Eric James. I grew up in the mountains of Colorado and have been an outdoors enthusiast since I was a young boy. I love skiing, hiking, camping, and fishing, and believe that nature has a way of calming the soul and renewing the spirit. I created "outwardlab.com" to share my passion and help others enjoy the outdoors. I also cover prepping and emergency readiness to ensure that people are prepared for anything. Join me on my journey to explore and be ready for the great outdoors!