The Complete Guide to Your RV Water Heater

Having running water while on the move is great, but Hot water is even better!

Join us for a quick swim through the ocean of information about RV water heaters. In this article, we’ll cover the different types of water heaters for campers, how they work, and how to maintain them. Let’s get started.

Types of RV Water Heaters and How They Work

Though RV water heaters operate similarly to their counterparts in a stationary home, you’ll need to understand a few differences to get the most out of them.

For decades, RVs had water heaters with very little variation. Now, you’ll find a few different types on the market. Determining which one will work best for you requires understanding what’s available and how they function.

Tank RV Water Heaters

Tank RV water heaters are the most common, have been around the longest, and are most similar to residential water heaters. However, many homes are starting to go tankless, just like RVs. A tank water heater fills a holding tank with water, generally between 6 and 12 gallons. Because of the small capacity, these heaters usually heat water to a higher temperature than in a home, and you need to be careful to prevent scalding. Even with these higher temperatures, you will not have as much hot water as you do at home and will run out if taking a long shower.

This type of heater has the advantage of being able to run on either electric or propane (if equipped). In electric mode, an electric heating element heats the water from shore power. In gas mode flipping the switch for the water heater sends electricity from a 12V house battery to ignite a propane burner. The burner heats the water. When you open the faucet, hot water flows from the tank out the spout.

There’s very little electricity needed for these types of RV water heaters in propane mode, just enough from the house battery to operate the switches and safety features. In addition, some of these water heaters can operate both electric and gas modes at the same time. This heats the water even faster and shortens the “recovery” time of a cold tank.

Older-style tank heaters may have a manually operated pilot light, which you would have to light by hand. Newer tank heaters sometimes have 120V electrical compatibility to run on shore power or a generator. But it takes longer for the water to heat from an electric element than a propane burner.

The main manufacturers of tank RV water heaters are Atwood (now owned by Dometic) and Suburban.

Pro Tip: To fully understand your RV water pump, you’ll need to know What Does an RV Accumulator Tank Do?

Tankless/On-Demand RV Water Heaters

Tankless or on-demand RV water heaters promise instant hot water with no waiting for the water to heat up. Tankless water heaters work by heating water as it moves through pipes en route to the faucet. These heaters are only available in propane for RVs. You can find electric versions for use in homes, but the power requirement is too high to use electricity even on a 50-amp RV.

In general, tankless units cost more and are more complex than their tanked counterparts. Many models are more sensitive to low water pressures and may have a hard time maintaining water temperature and can get too hot or cold.

Some on-demand systems are not tankless but offer the same promise of instant hot water while also reducing the possibility of scalding water at the faucet. These systems, like the Truma AquaGo, have a small tank that mixes and preheats the water so you get the temperature you want every time.

Tankless RV water heaters are newer to the market but have quickly become a favorite among RVers who want to take long showers or not wait for a water tank to heat up. The drawback is that you cannot use it on electricity when plugged in. Luckily these units are much more efficient with their propane use and will last a very long time on a tank.

➡ Learn more: Why We Love Our Truma AquaGo On-Demand Tankless RV Water Heater.

Combination Water Heaters

Combination units combine the water heater and furnace features into one unit. These units usually are designed for small RV’s with limited space. Examples of combination heater/water heaters are the Truma Combi and the Alde system.

Combining the furnace and water heater allows the appliance to take up less space, reduces weight, and increases efficiency. They come in propane only and propane/electric combinations that offer a variety of trade-offs, such as energy-saving modes or increased heating speed.

Hydronic or Boiler Systems

A diesel hydronic system, like the Aqua-Hot and Oasis models, also combines the furnace and water heater. Unlike the other combination appliances, a diesel hydronic system is usually tankless (or has a small backup tank) and can provide an endless hot water supply.

If your motorhome runs on diesel fuel, a diesel hydronic system can operate from your RV’s fuel tank, with electricity from shore power or with excess heat from the engine while driving.

This system uses a diesel-fired boiler to warm a heat exchanger filled with antifreeze that circulates throughout the RV. Fans circulate the heat in various zones. It also warms water that runs through coils wrapped around the boiler to provide hot water.

These systems are almost the same as a boiler-type heating system you find in some homes. Another benefit of the diesel hydronic system is that this heat can warm the rig’s diesel engine block so it will start in cold temperatures.

What to Know Before First Using Your RV Water Heater

Just like the other appliances and systems in your rig, it’s a good idea to know as much as you can about your RV water heater before its first use.

Where Is It Located?

Typically, the tank will sit near the bathroom or kitchen, with the ignition system and drain behind an access panel on the RV’s exterior. You’ll find the control switch for the hot water heater inside your rig.

How Do I Control My Water Heater?

The switch inside your RV can turn it on and off. If you don’t use a lot of hot water, you don’t need to leave it on. If the unit is gas or electric, you will have two switches: one for propane and the other for electric.

Many tank water heaters are set to a specific fixed temperature and don’t have an adjustable thermostat. A few have an adjustable thermostat near the ignition controls via the RV’s exterior access panel. Many on-demand and combination furnace/water heater appliances have temperature controls on a control panel inside the RV.

Should I Leave My RV Water Heater on All the Time?

You can safely leave your RV hot water heater on when not moving. Turning a propane-powered heater off is safer if you travel, however. But electric-powered ones won’t make a difference.

Leaving your hot water heater on all the time could cost a bit more in fuel expenses if you run off propane or a generator, but it won’t damage the hot water heater.

Should I Run It on Gas or Electric?

Gas burners heat water faster than an electric element. Also, RV water heaters use a significant amount of electricity, so you can’t always run appliances like an air conditioner at the same time as the water heater without tripping a breaker, especially when connected to a 30 amp supply.

If you connect to shore power and aren’t in a hurry, electricity will do fine. But if you go boondocking, a propane-fired heater saves energy. It uses a minimal amount of electricity from the house battery and requires a relatively small amount of propane.

How Long Do RV Water Heaters Last?

Most tank RV water heaters last about 10-15 years with proper maintenance. However, some can last much longer depending on the quality, upkeep, and usage. Tankless water heaters can last 20 years or more. But this also depends upon proper maintenance. Many tankless water heaters also have replaceable parts that can help extend their lifespan.

RV Water Heater Maintenance

Like a stationary home, RVs require maintenance. This includes your water heater. However, with regular operation, it doesn’t take much to maintain.

How Often Should I Drain My RV Water Heater?

The basic rule of thumb is to drain your RV’s water heater any time you won’t use it for a month or more. This prevents mold, mildew, or bacteria from having a chance to bloom in your tank.

You’ll also need to drain it before storing your RV for the winter, as any water left in the system could freeze and cause damage.

How to Clean Your RV Water Heater

Even if you constantly use your RV, you should drain and clean the water heater at least once a year. This helps remove any scale deposits and build-up that occurs. Different water heater types are going to require different procedures, so consult your manufacturer for instructions.

To do so for a common tanked water heater, turn off all of the water for your rig and shut off the electric and gas supplies to the water heater. Remove the drain plug or anode rod to empty it. Use a rinsing wand or the city water supply to flush the appliance.

Once you have rinsed the RV water heater, reinstall the drain plug or anode rod. With a winterizing kit or your fresh water tank and water pump, fill the unit with a 50/50 water and white vinegar blend. Turn on the water heater and allow it to heat up and sit for about 8 hours. Then turn off the power and gas again and let the mixture sit overnight.

After the mixture has sat and cooled, drain and rinse the tank again. You’ll likely have more debris come out in the water. This is normal. Reinstall the drain plug or anode rod. Remove the aerators from your faucets so they don’t collect debris, and open your faucets (hot and cold) until the vinegar smell goes away. You can now reinstall the aerators.

After completing this process, your RV water heater should be good to go until your next annual cleaning.

For tankless, hydronic, or combination units, the cleaning procedure will vary by manufacturer, and you will need to look up your model for the proper procedure. Below is how we clean our Truma Aquago.

Anode Inspection and Replacement

The anode rod is part of the drain plug on some RV water heaters. It collects corrosive elements that could degrade the hot water tank. You should inspect the anode rod at least once a year. Replace it when about half of the rod has corroded.

We’ve put together a complete anode rod replacement guide for you, as you can save loads of time waiting for a service appointment and do it yourself. It’s not as hard as you may think!

How to Winterize Your RV Water Heater

To winterize your RV water heater, follow the regular cleaning procedure first. Then use your RV water heater bypass to drain and bypass the tank, so you don’t have to put antifreeze in it. If your RV doesn’t have a water heater bypass, follow your standard winterizing procedure and place 1 to 3 gallons of non-toxic antifreeze in the tank.

Hint: You can also use an air compressor to winterize your RV without messy antifreeze.

However, if you have to winterize a RV tankless water heater, you will need to follow special and different instructions. Generally, this process is much easier than with tank heaters, but you’ll definitely want to follow the specific manufacturer guidelines for your particular model.

Can You Replace Your RV Water Heater?

Yes, you can replace your RV water heater with either a tank or tankless solution. 

If you are a handy DIYer, you can find plenty of YouTube videos and reliable websites that can walk you through either process. If you don’t want to tackle such a job, you can hire a certified RV technician to do it.

What’s the Best Water Heater for an RV?

Most RV manufacturers don’t offer many water heater options. You typically get whatever comes standard in your RV.

However, if you want to upgrade or look at different options, here are some things to consider. Whether opting for an RV water heater with or without a tank, choose one that works off both propane and electricity for the most flexibility in operation. Also, stick to reliable brands with a reputation for longevity and backing their products.

For an RV water heater with a tank, you can consider the respected brands of Suburban or Atwood. Suburban has a good reputation for its solid steel tank with porcelain liner and a built-in anode rod. Atwood models have good insulation and aluminum construction, which removes the need for an anode rod.

Tank water heaters typically only have 6 to 12 gallons in volume. If you want an on-demand water heater for longer showers, consider Furrion, Girard, Stiebel, and Truma. Just be sure that the on-demand model you choose has flow and temperature controls to prevent scalding water.

Personally, our top pick for water heaters is the Truma AquaGo. They charge a premium price, but the product has performed flawlessly on and off-grid for many years.

➡ Check out our other on-demand water heater recommendations here: 6 Best RV Tankless Water Heaters for Instant Hot Water.

Which One Is Better: Tank or Tankless?

If you want to purchase a new RV or water heater, we’d recommend tankless for its ease of operation and an endless supply of hot water, despite the price. However, budget-conscious buyers can still find great options for standard tank water heaters.

Regardless of whether your unit has a tank or not, you can get a lot of life out of it. Like most RV appliances, following a regular maintenance schedule will maximize your RV water heater’s life and the comfort you get from it during your travels.

What type of water heater does your RV have? Drop a comment below.

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