The Ultimate Guide to RV Water Heaters

We were on the road, living and working in our motorhome, for over 20 years, so we know that having hot water any time you need it is a real luxury. But it’s one we’d rather not ever have to do without. That’s why we’ve created this guide to the RV water heater. The more you know about the appliances in your RV, the better you can maintain them properly and troubleshoot them if needed.

We’ve included just about everything you need to know about your rig’s water heater, right here in one place. So, without further ado, let’s jump right in!

How Does an RV Water Heater Work?

A standard RV water heater functions very much like one you’d find in a sticks-and-bricks house. The main difference is that a home water heater is much larger than an RV’s. So, while a home may have a 40- or 50-gallon capacity, for example, a water heater in an RV generally has a 6 to 12-gallon tank.

However, the appliance itself functions very much the same as those in a fixed-location home, using a source of heat (electric or propane) to warm water in a tank. There are just a few different ways in which various types heat the water in the tank, depending on the type of water heater you have.

Electric

Electric water heaters use an electric heating element to heat the water in the tank. In an RV, this typically means you need access to 120V AC (from shore power or a generator) to power the electric element (though there are options for 12V RV water heaters, too). The element heats the water in conjunction with input from an electric thermostat.

Gas

A propane water heater is great for boondocking as it uses virtually no electricity.

With an LP gas water heater, a small spark is produced from a 12-volt power source that ignites the burner. That spark, along with the thermostat that controls the heater, is why gas units use “virtually” no electricity (but not zero). They simply need a small amount of 12V power to ignite and control them, but no electricity at all is used to actually heat the water.

With a standard gas water heater, a switch on a panel inside the RV ignites the pilot light to begin heating.

Instead, the pilot light ignites the gas at the burner, resulting in combustion that heats the water in the tank.

Once you turn on the switch to begin the heating process, it can take about 10-30 minutes (depending on the size of the water heater’s tank and the temperature of the water in it) for the water temperature to rise to its maximum temperature, typically about 120 degrees Fahrenheit.

Gas/Electric

Your RV water heater may also work on either gas or electricity to supply hot water. These are sometimes referred to as 2-way heaters. But they’re so common that they’re often simply referred to as “RV water heaters.” That’s how ubiquitous they are.

This is the type of unit we had for most of our 20+ years of full-time living on the road (and is the style we have now in our Outdoors RV travel trailer), and they do a perfectly fine job. When hooked up to shore power, the 120V AC element can be used to heat the water. When off the grid, we use propane.

What Is a Standard Water Heater In an RV?

As noted above, a standard heater in an RV is typically a “tank” style that runs on either gas, electricity, or both. Tanked RV water heaters generally have a 6 to 12-gallon capacity.

* PRO TIP: With a standard 2-way water heater, if you want hot water as quickly as possible after arriving at a campground, use BOTH modes. That’s right, use the propane and electric side simultaneously to heat water more quickly (as long as you have 120V AC and enough propane available).

Most commonly, standard RV water heaters have been supplied to RV manufacturers by one of two companies:

Suburban

Suburban, a top manufacturer of RV water heaters, furnaces, ranges, and induction cooktops for more than 70 years, is owned by Airxcel. Suburban is one of the most common brands of water heaters found in RVs. Our rig came with quite a large bi-fuel Suburban model, actually — 12 gallons! That’s incredibly luxurious in an RV (though our new travel trailer water heater, a 6-gallon Suburban gas-electric model, has been supplying us with all the hot water we need, too)!

Atwood/Dometic

Atwood, now a part of the Dometic family, has been making water heaters and furnaces for recreational vehicles and mobile homes since 1964.

The two most common brands of standard RV water heaters have long come from Atwood/Dometic and Suburban.

Are There Other Types of RV Water Heaters?

In addition to the standard propane/electric tank models typically found on an RV, other types are increasingly being used. On some newer RVs, these systems may come installed by the manufacturer.

In other cases, an RV owner may opt to replace an existing water heater with one of the following types, either because their current water heater failed or because they want a different type of water heating system for other reasons. We did the same thing when we upgraded our old motor home water heater to a Truma AquaGo Comfort+ on-demand system several years ago (more about that below).

The other types of RV water heaters that are commonly available include:

Tankless (On-Demand) Water Heater

A tankless water heater (sometimes… and sometimes more accurately… referred to as “on-demand”) doesn’t use a traditional tank to store and heat water. With a tankless system, when you “demand” hot water by turning on a faucet, it’s heated virtually instantly as it passes through the unit.

This means no more waiting 20-30 minutes (or more) for your water to heat. It also reduces weight because you’re not carrying around a tank holding 6-12 gallons of water (at 8.34 lbs per gallon, that adds up pretty fast).

Plus, with a tankless/on-demand model, the only limitation to how much hot water you have available is how much water you can access (either from your fresh water tank or from a city water connection) and how much propane you have available. This is often the reason RVers want to switch from a tank-style heater… the virtually limitless supply of hot water for more residential-style showers, etc.

However, these units tend to be a bit more expensive, typically averaging around $1,200-1,600. By comparison, a traditional 10-gallon tanked model can often run closer to about $800 or less.

Two of the main producers of on-demand/tankless water heaters are Truma and Girard.

Truma

Truma, a leading European RV component supplier, has been gaining steady traction in the North American market with its on-demand heaters and combination furnace/water heaters. We’ve had a Truma Combi on every RV we’ve rented abroad, and they provide fantastic heat AND hot water for the whole rig.

Among Truma’s long list of great features is the quickest, easiest winterizing process you could imagine. We could literally winterize the unit in about 30 seconds!

Another model, the Truma AquaGo on-demand water heater, is fast becoming a popular choice in North America. We had an AquaGo Comfort Plus model installed in our old RV, and we absolutely loved it.

With a very small water tank, the AquaGo isn’t actually “tankless,” hence the more accurate “on demand” designation. It also runs on propane only but uses such a small amount (it’s VERY efficient) that we were fine with using it even when connected to shore power (where we’d normally switch to using 120V AC to heat water to save propane).

We loved our Truma AquaGo Comfort Plus. We had ours installed to replace a standard water heater in our 2005 Newmar Mountain Aire, but these excellent on-demand water heaters are a great standard feature in some newer RVs.

Girard

Girard was among the earliest companies to offer tankless water heaters to the RV market, and they’ve continued to advance their product over time.

For much more information on tankless systems, please see our full post on RV tankless water heaters.

Hydronic Water Heater/Heater

Hydronic heaters/water heaters provide both heat and hot water from a single system, and are becoming a popular choice for manufacturers because they replace both the RV water heater and the propane furnace. These systems provide both on-demand hot water as well as heat throughout the entire RV.

A hydronic system typically uses a diesel-fired boiler, so most heating systems require a diesel fuel tank. However, some use propane as their fuel, and others operate using gasoline. An electric heating element is often included as part of the system to provide heat & hot water when the rig is connected to shore power (though, because of power limitations, using just 120V AC may not be enough to keep up with hot water and heating demand in very cold temps).

You can learn much more about hydronic systems for RVs in our complete post on RV hydronic heating systems.

The companies most commonly producing hydronic systems for the RV industry include:

Aqua-Hot

Aqua-Hot systems offer diesel, propane, or even gasoline-powered heating.

ITR Thermal Research

ITR is known for its diesel powered systems, in particular the popular Oasis systems.

PrecisionTemp

PrescisionTemp offers propane-powered hydronic systems.

Alde

Alde also offers propane-powered systems.

Truma Combi

Truma Combi systems are propane/diesel/electric hydronic systems. As mentioned above, we’ve actually had personal experience with this one on rental RVs abroad, and they’re sweet little units. We’ve had a Truma Combi as the combined forced hot air heat and hot water system on virtually all of the Class B+ style RVs we’ve rented overseas, and we’ve really liked it.

Truma offers hydronic systems for all RV sizes, including the ECO, ECO Plus, Combi D (for diesel) and Comfort Plus.

Can I Run My RV’s Water Heater on Gas and Electric at the Same Time?

Yes! We’ve done it many times. For faster hot water recovery (for example, when people are taking back-to-back showers), you can use propane gas and electricity simultaneously. It’s handy for quickly heating a tank of water when you arrive at your campsite and want a fast shower.

This will speed up the heating of the water, but keep in mind that in order to utilize the electric side, you’ll need 120V AC shore power or a generator.

How Long Should an RV Water Heater Last?

According to Energy.gov, a typical tankless household water heater should last in the neighborhood of 20 years with proper maintenance. We don’t see similar reporting for tankless RV water heaters but would imagine a well-cared-for unit should similarly provide many years of service.

Although we’ve typically read that a traditional standard (tank-style) RV water heater should last around 10-15 years with proper maintenance, that’s probably a generalization based on part-time use by vacationing RVers.

That said, there are RVers on the road with 20-year-old standard RV water heaters that are still working fine. There are also those who’ve had to replace theirs after a few years… so, your mileage may vary. But maintenance is always key!

Speaking of water heater maintenance…

RV Water Heater Maintenance

The best way to keep your RV water heater working well to deliver hot water whenever needed is to tend to regular maintenance.

Let’s take a look at the four most important things you can do to keep your RV water heater in good working order.

Keep Water in the Tank

If you’ve got a standard tank-style RV water heater, be sure there’s water in the tank before you turn it on! Turning on a water heater that doesn’t contain any water to heat will burn out your heating element quickly.

You might wonder why there wouldn’t be any water in an RV’s water heater tank, but some people drain and bypass their water heater during the winterization process, but continue to use their RV (think ski trips, etc). Accidentally turning on your water heater with an empty tank can cost you a heating element.

Winterize!

If you store your RV during the winter (or like to travel in colder climates), you’ll likely need to winterize your RV’s plumbing. During the winterization process, you’ll need to drain the water heater. If this isn’t done, water in the heater can freeze and damage the tank, requiring the replacement of the entire unit.

To drain your standard RV water heater tank, you’ll simply pull the drain plug (Atwood/Dometic) or anode rod (Suburban), open the over-pressure relief valve, turn all faucets on to full hot, and allow the tank to drain.

Note that there’ll be a small amount of water left in the bottom of the tank, but that won’t be a problem. As long as there’s plenty of room in the tank for it to expand as it freezes, it won’t cause damage to your tank.

NOTE: don’t stop there… you’ll need to do plenty of other tasks to finish winterizing your RV. Check out our article with all sorts of other RV winterizing tips.

Replace the Anode Rod (Suburban Water Heaters)

Suburban water heaters have steel tanks, requiring them to come equipped with a metal rod called an anode to reduce corrosion. Atwood heaters have aluminum tanks, so they don’t have anode rods.

Anodes are sacrificial rods, usually made of aluminum or magnesium (or an alloy of both). Its job is to react with minerals in the water that would otherwise corrode the tank, sacrificing itself instead.

Anodes should be inspected at least annually. Replace your Suburban anode rod at least once every year or two, depending on how much it’s decayed.

The job of an anode rod is to sacrifice itself for the benefit of your water heater. As you can see in the photo, the old rod has corroded, saving the heater itself from corrosion.

How quickly an anode rod decays generally depends on how much you’ve used your RV and the composition of the water that goes into the tank.

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Important note: If you’re going to flush & descale your tank (see next step), you don’t want to replace the anode rod until after that procedure is complete!

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Clean and Descale Your RV Water Heater

Sediment will build up in your RV water heater over time (especially if you RV in areas with hard water), so annual flushing and descaling should be included in your maintenance routine.

We’ll note the general steps here, and then we’ll include a couple of videos showing you exactly how to maintain a Suburban water heater tank and an Atwood/Dometic brand as well, step by step. In general:

1. Turn off the water, gas, and electrical supply to the water heater and wait several hours (or even overnight) for the hot water tank to cool (to avoid being scalded, avoid draining your water heater with hot water in it).
2. Open the over-pressure relief valve and remove the drain plug (Atwood/Dometic) or anode rod (Suburban) to drain the tank.
3. Insert an RV water heater flush wand on the end of a garden hose to wash out the inside of the tank.
4. Fill the tank half-full with white vinegar, and fill the rest of the way with water, for a 50/50 vinegar/water mix, and let it sit (overnight if possible) to dissolve any large sediment pieces.
5. Thoroughly rinse the vinegar out of the tank and put the drain plug or anode rod back in place, then refill the tank.

Here are the videos we mentioned, showing you exactly how to flush and clean a Suburban RV water heater and an Atwood/Dometic RV water heater:

Troubleshooting Common RV Water Heater Issues

You may never have an issue with your rig’s standard water heater… but there are a number of issues that can crop up, so we want you to be prepared to troubleshoot them just in case. After all, no one wants to return from a satisfying mountain hike, sweaty and ready for a nice shower, only to be greeted by cold water!

If that should happen to you, we refer you to our post on RV water heater troubleshooting to sort through the possibilities. Whether you’ve got a faulty thermostat or a failed heating element (or anything else), we think we’ve got you covered in that post.

We also want to note that some odd but straightforward things can happen to cause your heater to stop producing hot water. One of those odd things happened to us very early in our RVing life, way back in 2003. We’ve detailed it for you (along with other tips) in our post about having no hot water in our RV. (Spoiler: We inadvertently caused the problem ourselves!) Want to see what we did to shoot ourselves in the foot? DOH!

Generally, if you take care of your RV’s water heater, it’ll take care of you.

And when your RV’s water heater has reached the end of its lifespan, you’ve got a couple of good options for replacing it.

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