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Hot Water Heater for an RV: Everything You Need to Know

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Illustration of an RV water heater element highlighted within a recreational vehicle.

One of the greatest joys of RV ownership is having the comforts of home while on the road. One of these comforts is a consistent supply of hot water for cooking, cleaning, and showering. This article will dive deep into the world of RV water heaters. We will explore the mechanics of how these appliances work, their types, and crucial aspects to consider before investing in one.

Understanding How RV Water Heaters Work

Just like residential units, RV water heaters heat the water in your vehicle. How exactly do these water heaters work? Water from your supply (either an external hook-up or your RV’s freshwater tank) flows into the water heater’s tank. Here, either a gas burner or an electric element heats the water to the desired water temperature.

For safety, these heaters are equipped with a hot water pressure relief valve. As the water heats up, it expands, increasing the pressure inside the tank. If the pressure exceeds the safe limit, the pressure relief valve releases some water to reduce the pressure.

The water heaters most commonly found in RVs are Dometic Atwood or Suburban, and operate in the same way. RV tanks can hold between 6 and 12 gallons. Some models come with a water heater on request or as an option.

Water Heaters Duration

A common question is how long it takes for the RV water heater to heat the water. Typically, it takes about 20 to 30 minutes for the water to heat up sufficiently after turning on the heater. This time can, however, vary depending on the water heater’s capacity and power source.

Some water heaters are fast-recovery models. They can quickly heat a certain quantity of water, usually between 12 and 20 gallons per hour.

This requires no intervention on your part. It allows you to assess how quickly your water heater will be able to supply your needs in hot water again when empty.

The Different Types of RV Water Heaters

There are mainly two types of RV water heaters: tank-based water heaters and tankless systems. Both have their pros and cons, and the choice between the two will depend on your specific needs.

Tank-Based Water Heaters

These are the most common types of RV water heaters. They work by storing water in a tank and heating it up. These water heaters can use either gas, electric power, or both.

Gas water heaters usually heat water faster than electric ones. They require a propane supply, which can be a limiting factor for some travelers.

The anode rod is a vital part of tank-based water heaters. It’s a sacrificial rod made of magnesium or aluminum with a steel core. It’s designed to corrode before your water tank does, prolonging the life of your water heater.

RV Tankless Water Heater

The RV tankless water heater, as the name suggests, doesn’t use a storage tank. Instead, it heats water as required or on demand. This system uses a heat exchanger to heat the water as it flows through the heater.

When you turn on a hot water tap, the tankless system senses the water flow. It, then, fires up to heat the water to the preset temperature.

The Advantages and Drawbacks of RV Water Heaters

Each type of RV water heater has its unique set of benefits and drawbacks.

These water heaters operate on either 120V electricity or propane. You can toggle between the two energy sources from switches in the RV control panel. Most water heaters are now DSI, or “Digital Spark Ignition”.

Simply turn the switch for the desired source to “ON”. The element will heat directly if the source is electric. The water heater pilot will light itself if the source is propane, eliminating the need to manually light it outside.

Some panels feature an indicator light between the two switches. If it lights up, the ignition sequence has failed.

Tank-Based Water Heaters

The main advantage of tank-based water heaters is that they can store hot water. It is ready when you need it. They’re also typically less expensive than tankless systems. However, they do have some downsides.

They take up more space due to the size of the tank. The supply of hot water is limited to the capacity of the tank. Once the hot water is used up, you have to wait for the heater to heat more water.

Tankless Water Heaters

The most significant advantage of a tankless system is that it provides a continuous supply of hot water. Naturally, the hot water will be available as long as you have a water source. They’re also smaller and lighter than tank-based systems, making them ideal for space-limited RVs. However, they’re typically more expensive and can be more challenging to install.

Considerations When Choosing an RV Water Heater

When choosing an RV water heater, you should consider the following aspects:

  1. the installation process
  2. customer service from the manufacturer,
  3. the capacity of the heater,
  4. whether the heater is a gas, electric, or combination unit.

An electric water heater may be a great choice if you often stay at campsites with electrical hookups. On the other hand, gas water heaters are excellent for dry camping, as they don’t rely on electricity. However, many RV owners prefer units that operate on both gas and electric for maximum flexibility.

If you use propane gas, it’s not advisable to leave your water heater on at all times. You’ll be consuming gas without needed it. It’s best to turn it on a few minutes before you need it, for example, when showering or washing dishes.

When looking for an RV water heater, you’re likely to encounter several brands that are well-known in the industry. Here’s a look at some popular ones and what they have to offer.


Suburban is a top-rated brand in the RV water heater market. They manufacture both tank-based and tankless systems, providing options for every kind of RV owner. Suburban heaters are known for their durability and efficiency.


  1. Wide variety of models to choose from.
  2. Well-built and long-lasting.
  3. Known for efficient heating.


  1. Some users have reported customer service to be less responsive.
  2. Certain models might be challenging to install without professional help.


Atwood is another reputable brand that produces both gas and electric water heaters. Their units are lightweight, compact, and efficient, making them a great option for smaller RVs.


  1. Efficient and quick heating.
  2. Lightweight and compact.
  3. They offer both gas and electric models.


  1. There have been some reports of difficulty in sourcing parts for older models.
  2. Some users have reported their units to be noisier than others.


Mor-Flo is renowned for its advanced RV water heating solutions. Many RV owners appreciate Mor-Flo’s heaters for their quiet operation and efficient performance.


  1. Well-built and long-lasting.
  2. Efficient performance.


  1. Difficult sourcng parts for older models.
  2. Some users have found the installation process challenging.

Girard – Trauma

Girard specializes in tankless water heaters, and they’re known for their innovation in this area. Their units offer unlimited hot water supply and are particularly popular among those who prefer boondocking or dry camping.


  1. Unlimited supply of hot water and quiet operation.
  2. Compact and lightweight.
  3. Highly efficient heating. / Trauma offer both tank-based and tankless systems)


  1. Generally more expensive than tank-based water heaters.
  2. The flow rate may fluctuate at times, leading to variations in water temperature.
  3. Does not allow powered anode to be installed to protect the system from corrosion – maintenance must be done more often. Some users have found the installation process challenging.

Maintenance, maintenance, maintenance

Before servicing your RV water heater, it’s important to make sure it’s switched off. And hasn’t been used recently, to avoid burns caused by hot parts or escaping water. It’s important to check the condition of the RV water heater’s anode. We recommend doing so when preparing the RV for the winter season.

The anode is made of aluminum, magnesium or powered and is designed to react with particles and minerals in the water. The anode will corrode in place of your water heater’s tank, prolonging its life and ensuring its smooth operation. The anode is accessible behind the outer panel; simply unscrew it to remove it for inspection or replacement.

We always recommand the long term game when it comes to anode replacement. The Corro-Protec RV powered anode will not deplete as it is made of titanium. It will also eliminate the foul smell (also known as rotten egg smell) and significantly reduce sediment build-ups.

Water will leak out, since the anode is on the side of the water heater, not on top. The seal may fall off as it slides off the anode. Be sure to replace the seal on the anode before installation.

It’s also important to ensure that the water heater is full of water before turning it on. This step is often overlooked when preparing your RV for summer use.

When preparing your RV for summer use, be sure to return the bypass valve to its closed position. Reopen the water heater’s inlet and outlet valves. The water will then recirculate through the water heater.

You can verify that water is in by opening the water heater’s safety valve. This valve is accessible through the water heater panel on the outside of the RV.


Choosing the right water heater for your RV can greatly enhance your travel experience. Whether you opt for a tank-based or a tankless system, if you:

  • understanding how RV water heaters work
  • what to look for

These 2 items can help you make an informed decision.

And remember, the goal is to ensure a consistent supply of hot water. If you’re on the road, it will make your RV feel even more like home.


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