The Best RV Tankless Water Heater Guide: Everything You Need to Know

    RV parked on a vacation

    An RV water heater is one of the many features RV's are equipped with to make your home-away-from-home comfortable and pleasant. Much like a residential water heater an RV heater provides you with hot water, and although there are many similarities, there are also major differences.

    We Have Done the Research for You

    If you know how a RV water heater works and how to keep it maintained, you'll be a step ahead when something isn't functioning as it should. This guide will help you learn what to look for when you're ready to purchase a new RV in the market for the best RV tankless water heater -  or it's time to replace the water heater.

    How to Pick the Best RV Tankless Water Heater

    RV crossing river on a rock bridge

    Basics of RV Tankless Water Heaters

    Storage Capacity

    There are 3 main storage systems available with RV water heaters:

    • 6 to 10 Gallon Tanks - The majority of heaters have storage tanks capable of holding 6 to 10 gallons of hot water.
    • "16-Gallon Heaters" - These units have a 10-gallon tank where water is held at a high temperature. When a hot water faucet is opened, the hot water from the tank is mixed with cold water. The result: The water delivered is at the proper temperature. Since the hot water is mixed with cold water, the 10-gallon tank is capable of delivering 16-gallons of hot water.
    • Tankless - These systems deliver hot water within seconds of opening a faucet. When a hot water tap is opened, cold water flows thru the tankless unit to meet the demand. Although often more expensive initially, tankless water heaters are more energy efficient and therefore less expensive to operate since propane is only used when a hot water tap is open. Instead of the water heater cycling on and off whether hot water is needed or not.
    Group of RV's traveling on an Fall morning

    Types of Fuel Available

    RV water heaters have 3 primary fuel options:

    • Liquid Propane (LP) - Commonly used with entry level RV's.
    • Electricity and Liquid Propane - Most RV's use water heaters that are made to run on both electricity and liquid propane. Each fuel source can be used individually or used together to rapidly bring the water to temperature.
    • Motoraid - This sophisticated fuel source uses the RV's engine cooling system to heat the water. When the engine is running the water from the engine's cooling system circulates through the water heater, and in the process heats the water in the tank. When you arrive at your destination, your water is hot!

    Electric M​​ode

    Your RV water heater can operate in electric mode if you have generator power or 120v shore electricity. However, a substantial draw of 12 amps of electricity is required. If power is limited, you may still want to use LP Gas Mode.

    Another consideration is the shore power wiring. Some areas only provide 30A or less. In this scenario you may choose to switch to LP Gas Mode or turn off the water heater temporarily.

    Liquid Propane (LP) Mode

    Liquid propane water heaters have several different model types, with the main difference in the ignition system. There are 2 main types, the Manual Pilot Light and the more sophisticated Direct Spark Ignition. Let's take a closer look at each system:

    Open door on an RV in the evening
    Manual Pilot Light

    The most basic model of RV water heater uses a manual pilot light. The pilot light will need to be manually lit whenever it is extinguished. If the light goes out unexpectedly, there is a safety feature designed to prevent the LP gas from flowing.

    The pilot light will need to be lit once the RV reaches it's destination as the flame will be blown out from the wind.

    Direct Spark Ignition

    The most common RV water heater is the Direct Spark Ignition (DSI) system. Without a pilot light, a signal is sent from the gas mode thermostat to the heater control circuit board. When the signal is received, the gas valve opens and the igniter is activated and produces a flame.

    The flame is detected by a sensor which signals the water heater to turn on. However, if the sensor doesn't detect a flame after 15 seconds the gas valve will close, and an indicator light will signal to the user that the heater failed to light. 

    DSI heaters are designed to operate when the RV is traveling, however, it's important to note, that they will be using fuel during this time. Many owners prefer to wait until they reach their destination before turning on their water heater in order to save fuel. 

    Close up of RV access panels

    Maintenance of a RV  Water Heater Unit

    RV water heaters are relatively easy to maintain, and most owners should be able of doing the work themselves or at least performing preventative water heater maintenance. However, there are many places dedicated to RV repair and maintenance willing to do the work if you prefer.

    Anode Rod

    The anode rod in a RV water heater has the same function as your water heater at home. The sole function is to sacrifice itself in order to protect the steel tank from rust and corrosion. However, there are RV water heater tanks that are lined with glass and don't require an anode rod. 

    As a general rule of thumb, the anode rod should be checked every year. Some RV owners prefer to change them annually regardless of their condition, but this isn't necessary. Simply inspect it every 12 months and replace it as needed and you should be fine.

    Flushing the Tank

    ​Whenever the RV isn't being used, the water heater tank should be drained. In addition, it should be flushed at least once a year.  An inexpensive tank rinser wand will allow you to spray water deep into the tank to remove the sediment. Consistent tank flushing will extend the life of the RV water heater. 

    We highly recommend the wand listed below. It is inexpensive and easy to use.

    Camco Tank Rinser

    Camco Water Heater Tank Rinser-Cleanses and  Removes Sediment that Collects at the Bottom of RV Water Heater, Extends Life of RV Water Heater (11691)

    You'll also need a garden hose and an element socket wrench to check flush tank and check the anode rod. If the anode rod needs to be changed, you'll need to pick up the appropriate size and type for your water heater.

    How to Flush the Tank and Change the Anode Rod


    Winterizing your RV's water heater is an important part in keeping it in good running condition. When the tank is drained it should be able to cope with weather temperature fluctuations by expanding and contracting without damage. 

    The water lines will need to be winterized with anti-freeze. These lines are prone to breaking if not properly cared for since they are very thin. Frequently a bypass valve is installed to assist with winterizing.

    The purpose of a bypass valve is to keep the anti-freeze within the water lines from entering the tank. Although, many RV water heaters have these valves installed, if yours does not, there are bypass valve kits available.

    Bypass Valve

    JR Products DVH-1-A Hot Water Tank Diverter Valve

    If for whatever reason your tank does fill with anti-freeze, take care that it is thoroughly flushed prior to filling it with water for use. Ingesting anti-freeze can be a serious health hazard.

    Positioning the Valves to Bypass Your Water Heater

    Cleaning the Burner Tube

    The burner tube supplies gas to the burner when the unit is in LP Gas mode. This supply tube should be cleaned every year. Use a can of compressed air and simply spray in and around the burner tube. This task should be done every Spring

    RV on the road

    Troubleshooting  Details for Water Heaters 

    Gas Supply Tube

    The number one problem that causes an RV heater not to work is a clogged gas supply tube. If the tube becomes plugged, the gas won't reach the pilot assembly.

    ​The smell of propane attracts spiders and other small insects and they crawl inside the tube to build nests. Simply use a can of compressed air and spray in and around the burner tube. It's a good idea to do this anytime your RV has sat for an extended period of time or in the Spring. 

    ByPass Valve

    ​The bypass valve can be tricky and it is also a common source of water heater issues. However, with a little troubleshooting you'll be able to pinpoint the problem.

    • Open the pressure relief valve (located outside) to check the temperature of the water.
    • If the water is hot - The water heater is working. Check the bypass valve to make sure it is configured properly.
    • If the water is cold - Assuming that the water heater has cycled on and off, check the hot water valve. If it's in the off position, the water will not be able to leave the tank.
    • If you have hot water, but it quickly turns cold - The bypass valve is most likely still open. The heated water is mixing with the incoming cold water. 

    Heating Element

    Heating element failure is a common "first of the season" problem since it is easy to forget to take your water heater out of winterization bypass mode. If the water heater is turned on, but there isn't any water in the tank, the heating element will fail. 

    When the heating element isn't submersed in water it will quickly burn out and need to be replaced. Fortunately they are inexpensive and  relatively easy to remove and install.

    Electric Heating Element

    Suburban 520789 1440W Screw In Electric Element

    Unpleasant Smell

    If you notice an unpleasant smell when you run water from your faucets, there's a good chance that the problem is stale water. Although this can happen with cold water, the smell tends to be much worse with hot.

    The solution is as easy as draining and refilling your tank.

    How Long Can I Expect an RV Water Heater to Last?

    If you take care of your heater it can deliver hot water for up to 10 years. Draining, flushing, checking and changing the anode rod are all important parts of a strong preventative maintenance routine.

    RV bathroom

    Our Top 3 RV Water Heaters for 2019

    There's a lot of great RV water heaters available today, both tank-style and tankless. Whichever style your looking for, you shouldn't have a problem finding one that meets your needs. Here are 3 of our top favorites, including our picks for best RV tankless water heater:

    Girard 2GWHAM

    Girard is a very well established manufacturer of RV tankless water heaters. The 2GWHAM is easy to install, easy to operate, and very quiet due to it's brushless motor.

    If you enjoy RV'ing in the winter, this tankless heater is a great choice. With built-in freeze protection it's designed to eliminate cold weather worries.

    The on-board microprocessor monitors and tracks the incoming cold water temperature to ensure that the hot water is the exact temperature you desire. This is an excellent RV tankless water heater and is a favorite among long-time RV'ers.

    Girard 2GWHAM

    Girard 2GWHAM On-Demand Tankless Water Heater

    Precision Temp RV-550

    If you're looking for performance Precision Temp's RV-550 is the tankless for you. Don't let it's small size fool you. It may weigh only 32 pounds, but it out performs most other tankless water heaters!

    It has a hot water output of 55,000 btu and can deliver roughly 940 gallons of piping hot water on a 20-pound tank of propane. 

    Regardless of the season, you'll have a consistent temperature of hot water as the unit self-adjusts it's gas usage, by sensing the smallest changes of incoming water temperature and overall water flow.

    This RV tankless water heater is made to work in all four seasons, and even has built-in cold weather protection. But if travelling isn't your thing during the chilly months, you can easily winterize the RV-550 until the warmer weather comes.

    Precision Temp RV-550

    PrecisionTemp RV-550 Tankless Water Heater - Wall Vented

    Suburban Sw6De

    If you're shopping for a tank-style RV water heater, you might want to check out the Suburban Sw6De. Fueled by lp gas and electric ignition, it's energy efficient and versatile.

    With a 6-gallon tank and competitive recovery times, the Sw6De is a top performer within Suburban's line-up.

    Suburban Sw6De

    New Suburban Sw6De 6 Gallon Dsi Electric Ignition/Lp Lp And Gas Rv Motorhome Trailer Water Heater

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