New RV and a Primer on RV Water Heaters

Well we finally did it. We are now proud owners of a 2017 Fleetwood 30D. We want to thank everyone for their recommendations on a new RV. While we learn the ins and outs of this beauty, I wanted to share a primer my son put together on RV water heaters. He manages the excellent site Water Heater Hub (shameless plug).

RV Water Heaters Basics

A good RV hot water heater allows you to enjoy hot water wherever you are, whether it be camping or on a cross-country adventure. These water heaters operate more or less like residential water heaters with only a few differences. Knowing how they operate, how to maintain them, and how to troubleshoot them is key to years of trouble-free use.

RV water heaters are engineered smaller than residential models for obvious reasons. Models with 6-10 gallon tanks are by far the most popular. 16-gallon models are available but not very common due to their higher price and their requirement for more space. Like a residential unit, a water heater in an RV heats water up to the set maximum temperature and then mixes with cold water at faucet.

Tankless water heaters are becoming popular for RV. These are relatively expensive, but they offer the convenience of producing hot water in a few seconds on demand. Their operation is not different from that of tankless water heaters used at home.

Tankless water heaters for RVs have a reduced demand for fossil fuels besides offering an endless supply of hot water. With a conventional RV water heater, hot water is kept in the tank, meaning it is always cycling whether you are using the water or not. Tankless water heaters will only use propane when you need hot water. This means less refills and cost effectiveness.

Choosing Between Fuel Sources

You can choose between three fuel sources for your camper’s water heater. Electric and Liquid propane water heaters are engineered to operate on either Liquid propane or electricity. You can use the power source that gives you convenience or you can use both to heat water quickly.

Liquid Propane heaters burn Liquid Propane only. This is normally seen on entry level heaters. The third option is Motoraid. These are water heaters that use a complicated system. They are connected to the engine cooling system of your RV. As the engine runs, water from the cooling system is circulated through tubes connected to the heater’s tank. As the hot water circulates, it heats the water in the tank. Motoraid heaters are fuel efficient.

Understanding How RV Heaters Work

Electric Mode

Electric mode can be used on an electric hot water heater when you have about 120v shore electricity, or you have a generator. Irrespective, you will still need 12 amps electricity to keep the heater on which is a huge draw. When power is limited, you might need to switch to LP Gas Mode. Knowing the shore power wiring of your travel trailer and the outlet power will help you determine when to switch to LP Gas Mode or to switch off the heater temporarily.

Liquid Propane, LP Mode

You can switch to this mode when there is limited electric power. There are different LP water heater models with the main difference being in their ignition. Premium motorhomes have Direct Spark Ignition, which runs a sophisticated system.

Manual Pilot Light

This is a basic heater model. It uses a pilot light that you will need to light manually. When the pilot light is off, either by going off unnoticed or the pilot control has been switched off, gas does not flow. This is a safety measure that keeps you safe from gas leaks.

When the RV is on the road, the pilot light should be off. The wind usually blows the light off. This might be a minor inconvenience, but it will take about 20 minutes to have your water hot.

Direct Spark Ignition

The most common water heater in most RVs is the Direct Spark Ignition. This type of ignition has no pilot light. Instead, the gas mode thermostat will send a signal to the circuit board of the heater control to open the gas valve. Once this happens, a flame develops. The ignition system is fitted with a sensor, which detects the flame. When no flame is detected in 15 seconds, the gas valve closes. An indicator light will signal that the heater failed to start and the heater needs to be switched off.

When direct spark ignition is not working correctly, it’s similar to having a bad spark plug in a car and not much will happen. That’s why maintenance is so important. DSI heaters can operate even when the motorhome is on the road, but I prefer to wait until I stop to save fuel.

Maintaining Your RV Hot Water Heater

RV water heaters require less maintenance during normal use. The electric mode of your water heater, especially, is maintenance free. You should never worry about hiring a technician to take care of your heater as the process is quite straight forward.

Replace the Anode Rod

The anode rod is the part that protects the steel tank from corroding. If the tank on your RV hot water heater is made of steel, it is recommended that you change the rod annually. Note that not all tanks use an anode rod, some are protected by glass.

Remove the rod using a socket wrench. Seeing that the rod might not have been touched for a year, it might present a challenge to remove. My advice, expect to get dirty, but the procedure is really simple.

Drain Your Tank

Whenever you motorhome is not in use, you should always drain your heaters. You can also use a water heater tank rinser, which sprays water into the back of your empty tank to remove sediment. This is key in enhancing the life of your tank.

Fill Water Lines with Anti-Freeze

Water heaters are large enough to expand and contract without any damage. However, water lines are pretty thin and will need anti-freeze to keep them in shape. A wide variety of water heaters are engineered with a bypass valve that locks anti-freeze out of the tank and in the water lines. For water heaters that do not have bypass valves, there are special kits that you can install to do this. Before filling your tank with anti-freeze, make sure that you empty the tank completely.

Clean the Burner Tube

You need to clean the burner tube at least once a year. If you use the RV often, you need to clean it more often. By cleaning the tube in LP Gas Mode, you keep debris off and lengthen the life of your water heater. You can do this using a vacuum cleaner nozzle or by spraying compressed air.

Troubleshooting Your RV Hot Water Heater

Check the Gas Supply Tube

When the gas supply tube gets plugged, your water heater might not operate. Any obstructions in your heater’s gas supply tube will limit the flow of gas to the pilot assembly. Common obstructions are small insects and spiders, which follow the smell of propane. If your RV has not been used for a long time, clean the tubes before hitting the road.

Check ByPass Valves

When your travel trailer’s heater won’t operate, check the pressure relieve valve to ascertain that the water is hot. If the water is hot and can flow to the faucet, check the positioning of the bypass valves to make sure it is correct.

If your heater does not have hot water after cycling on and off, check your hot water valve. If the valve is switched off, no water will flow through. If the hot water flow gets cold quick, there is a chance that the bypass hose is open and is facilitating the mixing of hot and cold water.

Are the Electric heating elements working?

In winter, you winterize the bypass by filling the tank with anti-freeze. But sometimes people forget to take the tank out of this condition. Before using the electric mode of your heater, ensure that the tank has water. This protects the heating element from burning out. If your heating element has burnt out, you can always replace it.

Replace Stale water

When the heater produces an unpleasant smell, it is likely that there is stale water in the faucet. Water will become stale whether it is hot or cold. When this happens, drain the tank and the water in the lines. After refilling your tank, the smell goes away.

What is the Lifespan of Water Heaters for RVs?

A good RV water heater will last for more than 10 years. But this will depend on how well you take care of your water heater. I recommend you do a thorough maintenance and troubleshooting just before you store your camper and before you start using it after a period of storage. You need to drain and flush the tank, change anode rods, and ensure the valves and water heating elements are in good shape to keep it running smoothly for years.