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. 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 - or it's time to replace the water heater. Quick Navigation The Basics of RV Water HeatersRV Water Heater MaintenanceTroubleshooting Your RV Water Heater The Basics of RV Water Heaters Storage CapacityThere 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 end 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, they 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.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 thru the water heater and in the process heats the water in the tank. When you arrive at your destination, your water is hot!Electric ModeYour 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) ModeLiquid 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 system, the Direct Spark Ignition. Let's take a close look at each system:Manual Pilot LightThe 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 IgnitionThe 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 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. RV Water Heater Maintenance RV water heaters are relatively easy to maintain, and most owners should be able of doing the work themselves. However, there are many places dedicated to RV repair and maintenance willing to do the work if you prefer.Anode RodThe anode rod in a RV water heater has the same function as your water heater at home. There sole function is to sacrifice itself in order to protect the steel tank from rust and corrosion. However, there are tanks that are lined with glass that do not use 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 inspecting them every 12 months and replacing as needed should be fine.Flushing the TankWhenever 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. This video will show you how to flush the tank and change the Anode Rod.Needed Supplies:Garden hoseSocket WrenchNew Anode RodTank Rinser Wand WinterizingWinterizing 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 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 brass bypass valve will be installed to assist in 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. 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. This short video covers how the valves should be positioned when the water heater is in bypass and during use: Cleaning the Burner TubeThe 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. The best time to perform this task is every Spring. Troubleshooting Your RV Water Heater Gas Supply TubeThe 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 ValveThe 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 if the water is hot. If the water in the tank is hot, the water heater is working.Check the bypass valve to make sure it is configured properly.If the water is cold. (and 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 becomes cold.The bypass valve is mostly likely still open. The heated water is mixing with the incoming cold water.Heating ElementsThis is a common "first of the season" problem. It's 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. Unpleasant SmellIf you notice an unpleasant smell when you run water from your faucets, it's a good chance 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.