RV water heaters are used to heat the fresh water supply in order to provide hot water. They do this by heating a tank of water, which feeds the hot water piping just like in your home. However, in order to conserve space and weight this tank is smaller and generally runs either 6 gallons or 10 gallons in size. Hot water heaters are fired by propane but many models also have an electric heating element that can be used when shore power is available or when running the generator. Some models even have an optional Motoraide feature which will allow the engine's hot coolant to heat the water heater tank while driving.
Most RVs have a hot water heater, the main exception being if you have hydronic heating. The hydronic heating system also provides instant on-demand hot water so the traditional hot water heater is eliminated on an RV with hydronic heat. For more information on that system please refer to our Hydronic Heating document on this site.
Hot water heaters are made by two well known companies. You either have an Atwood hot water heater or a Suburban hot water heater. The biggest differences are that the Suburban hot water heater uses a steel tank while the Atwood uses an aluminum tank. Both tanks are glass lined but the Suburban uses a sacrificial anode rod to control corrosion in the tank while the aluminum clad Atwood tank does not use an anode rod. The anode rod will erode away over time in order to protect the tank so it should be checked on an annual basis. I just replace mine every year because they aren't that costly and if they erode too far they'll fall off and rattle around inside your tank and it'll be extremely difficult to remove it. For more information on these heaters refer to the following websites:
Check out the following links for detailed troubleshooting tips in water heaters:
Submitted by Mike Sundberg and Mark Quasius - 3/17/06