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Guide to RV Water Heaters: Everything You Need to Know

Guide to RV Water Heaters: Everything You Need to Know

We’ve been on the road living and working in our motorhome for over 20 years, so we know that having hot water any time we 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 & 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 10-gallon tank.

However, the appliance itself functions very much the same as those in a fixed-location home.

But there are 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 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.

Electric water heaters use a lot of power, so RVers with all-electric water heaters generally need to be connected to shore power or run a generator to use them.

Gas

Propane-powered water heaters are great for boondocking as they use 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 there’s no electricity at all required to heat the water.

The water heater panel in our RV

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

So, the pilot light ignites the gas at the burner, resulting in combustion, which heats the water in the tank.

When you press the button to begin the heating process, it can take about 10-30 minutes for the water temperature to rise to the recommended safe-water temperature, typically about 120 degrees Fahrenheit.

Gas/Electric

Your RV water heater may also work on either gas or electricity to provide the supply of hot water. These are sometimes referred to as 2-way heaters. But they’re so common, 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 on the road, and they do a perfectly fine job. When hooked up to shore power, the 120AC element heats the water. When off the grid, we use propane. The only exception to that is if our 7.5 kW onboard generator is already in use, we heat water on electric while that power is flowing anyway.

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 10-gallon capacity.

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

* PRO TIP: When we had a standard 2-way unit, and wanted hot water as quickly as possible after arriving at a campground, we used BOTH modes. That’s right, we can use the propane and electric side simultaneously to heat water more quickly (as long as you have shore or generator power available).

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!

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.

Atwood and Suburban RV water heaters shown side by side

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 be installed by the manufacturer.

In other cases, an RV owner opts to replace an existing water heater with one of the following types, because their rig’s 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 to our amazing Truma AquaGo Comfort+ on-demand system a couple of years ago (more about that below).

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 or 30 minutes or more for your water to heat. It also reduces weight because you’re not carrying around another tank holding 6-10 (or 12!) extra gallons of water.

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.

These units tend to be a bit more expensive, typically averaging around $1,000-1300. 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 our Truma’s long list of great features is the quickest, easiest winterizing process you could imagine. We can literally winterize the unit in about 30 seconds!

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 rig a couple of years ago, and we absolutely love it.

With a very small water tank, it’s not 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’re fine with using it even when connected to shore power.

Split photo showing an external view of the Truma AquaGo alongside the interior controls of the unit

We love our Truma AquaGo Comfort Plus. We had ours installed to replace a standard water heater in our 2005 Newmar Mountain Aire, but these awesome 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, so 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.

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, of course, need 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 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, 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.

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). Its job is to attract minerals 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.

New and old anode rods shown side by side

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.

Suburban 232767 Water Heater Anode Rod
  • Magnesium anode rod
  • For use in RV water heaters

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!

Camco Camper/RV Water Heater Tank Rinser | Improves Water Heater Function by Flushing Out Sediment | Easily Attaches to Standard Garden Hose & Features Convenient Shutoff Valve (11691)
  • EXTENDS THE LIFE OF YOUR WATER HEATER: The tank rinser lifts sediment that collects at the bottom of water heaters and flushes it out. This Camco RV...
  • IMPROVES WATER HEATER FUNCTION: This camper accessory helps prevent tank corrosion and also restores your hot water tank’s heating efficiency by...

Clean and Descale Your RV Water Heater

Sediments 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.

  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 simple 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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Normand Gauthier

Wednesday 1st of May 2024

How about a crash course on how to use a multimeter (basic for RV owner who knows about nothing).

Merci.

TheRVgeeks

Wednesday 1st of May 2024

Hi Normand. Probably not a topic many people would find interesting, but there are lots of videos that cover the basics on YouTube... you can check them out here: https://www.youtube.com/results?search_query=how+to+use+a+multimeter. There's not much specific to using one on an RV that isn't covered by just learning how to use one.

Randy

Tuesday 2nd of May 2023

Many water heaters heat to 140 degrees rather than 120. This is scalding painful hot.

JEROME NIETUPSKI

Thursday 4th of May 2023

@Randy, Mine is super hot too. I don't know if there is a way to "turn it down".

Terry Hurt

Tuesday 2nd of May 2023

We too have a 12 gallon Suburban in our unit. I'm glad to have never run out of hot water while showering!

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