Many leading RV manufacturers now include tankless water heaters as the standard option in top-selling campers. If you are upgrading your RV or comparing a model with a tankless heater to another with a tank-based design, consider these tankless water heater pros and cons.
Key Takeaways
- Pros: Tankless water heaters offer nearly endless hot water, improved energy efficiency, longer lifespan, and easier maintenance compared to traditional tank models.
- Cons: They can lead to wasted water, only operate on propane, require annual descaling, and may cause temperature fluctuations during use.
- Installation & Maintenance: Retrofit kits allow upgrading, though it may involve complex electrical and plumbing adjustments. Seasonal maintenance and winterization differ from tank-based systems and must follow manufacturer-specific procedures.
What Is an RV Tankless Water Heater?
Traditional RV water heaters have a tank that fills with water, either from your fresh water tank or a city water connection. That water is heated using a propane burner, an electric heating element, or both. However, you must wait for the tank’s content to warm to the setpoint before using hot water.
As hot water gets used, the tank fills with cold water, steadily decreasing the water temperature until it matches the temperature of the incoming cold water. That often means the best practice is to stop using hot water and wait for the tank to reheat before continuing your shower or dishes.
Tankless or on-demand water heaters work a little differently. They don’t have a traditional container to store and heat water. When you open a hot water fixture, a valve signals the water heater to turn on. Cold water then runs through a heat exchanger powered by propane gas to be warmed as it travels to that fixture. This design provides nearly constant hot water without the delay of heating a larger quantity of water in a tank.
Tankless Water Heater Diagram
Tankless Water Heater Pros and Cons
On-demand tankless water heaters deliver “limitless” hot water. But is there actually a limit? Are they better than models that heat water in a six or 10-gallon tank in all scenarios? Let’s explore the pros and cons of tankless water heaters for RVs.
Advantages of a Tankless RV Water Heater
Whether comparing RVs or pondering an RV upgrade, a tankless water heater will help you enjoy the following benefits.
Increased Energy Efficiency
With traditional water heaters, heat loss is inevitable when the water sits in the tank. Once you warm the tank’s capacity, you might not use all the hot water immediately. The remaining heated water cools, requiring additional propane or electricity to reheat it.
With a tankless design, propane is only burned when there’s a signaled demand for hot water. Thus, on-demand water heaters are considered more energy efficient than their traditional counterparts.
Shorter Wait Times
With traditional designs, you typically turn on the water heater and wait 10 to 30 minutes for the water in the tank to be heated sufficiently. This requires forethought, as you need to turn the heater on well before you plan to take a shower or wash dishes. But with a tankless water heater, you simply open the hot water fixture and enjoy warm water within seconds.
Improved Heater Longevity
On average, on-demand tankless water heaters have longer lifespans than traditional tank-based heaters. The two main factors responsible for their extended longevity are a simpler design and reduced wear and tear on the mechanical components. Because they only heat water when demanded, the chances of heat-related damage to internal parts go down..
Additionally, they have fewer components overall. There’s no storage tank that can crack or leak if not maintained properly, and there’s no tank lining or insulation that can degrade or become nest fodder for critters if your RV isn’t properly sealed for offseason storage. The simplicity of their design with reduced components means on-demand heaters last longer.
Easier Maintenance
Similar to longevity, tankless water heaters in campers are easier to maintain because they have fewer components. You won’t need to worry about periodic anode rod replacement or removing debris from the storage tank at the end of the season. Most manufacturers also offer designs with replaceable components that make repairs and maintenance easier over the heater’s lifetime.
Disadvantages of an On-Demand RV Water Heater
While they’re a great option, some RVers still swear by standard water heaters because of certain drawbacks related to tankless RV water heaters.
Can Lead to Wasted Water
With a traditional water heater, hot water delivery is nearly immediate as long as the heater has been turned on for long enough. The only cold water to purge remains in the line upstream of the heater.
But with tankless models, it can take a few seconds for the heater to bring the cold water running through the heat exchanger up to your desired temperature. Some RVers complain that this leads to wasted water, causing their gray tank to fill more quickly and shortening periods between RV dump station visits.
Only Operate on Propane
Many traditional RV water heaters feature a gas/electric design that allows you to heat water by burning propane, using an electric heating element, or employing both for faster heating times. This allows you to conserve propane for other appliances, such as a two-way refrigerator, furnace, or your cooktop. But with tankless water heaters in RVs, you’re restricted to propane-only operation, reducing your ability to pick and choose your fuel source.
Require Descaling
While tankless water heaters don’t require anode rod replacements or tank rinsing, they require an annual descaling procedure. Tankless heat exchangers are made of copper tubing and react with the minerals in hard water. This can lead to mineral buildups that you must remove annually. The descaling process entails disconnecting the supply and discharge lines and filling the heat exchanger with household vinegar or a similar descaling agent before flushing out the debris.
Can Be Subject to Temperature Swings
With a traditional water heater, you’d turn on the hot water and adjust the cold water output to reach your desired temperature. That temperature would remain fairly steady throughout your shower because the water in the storage tank is heated to the same temperature.
With tankless models, you can experience more regular temperature swings using this method. This is especially true if you turn the water on and off to conserve. However, some will recommend adjusting the heater’s output temperature on your internal thermostat so you can comfortably and safely only open the hot water fixture, as opposed to mixing hot and cold. This can reduce temperature variability, but you’ll still need to keep the water running to maintain your desired temperature throughout your shower or dishwashing.
Technician Tip: Newer on-demand RV water heaters have reduced original concerns related to energy usage and water consumption. More accurate incoming and outgoing temperature measurements, multi-stage burners, and even mixing valves and blending tanks are some of the advancements that mitigate these cold spotting issues. However, when deciding if an RV tankless water heater is right for you, it’s worth your consideration.
Can You Replace an Existing Water Heater with a Tankless Model?
Upgrading from a traditional RV water heater to an on-demand tankless model is possible, but it may require complex retrofitting if you don’t find a compatible replacement. Starting with the basics, the new heater must have a similar (or smaller) footprint.
Most tankless RV water heaters have a similar shape to traditional models and actually have a similar exterior access panel. Overall, the units are typically smaller because they don’t include a six or 10-gallon tank. Most major manufacturers offer precision retrofit kits that make this process accurate, efficient, safe, and attractive.
The steps for a tankless RV water heater replacement vary by heater manufacturer and compatibility with your RV’s water system. However, here’s an overview of the general process:
- Turn off and/or disconnect from all power and water sources (DC and AC power)
- Drain water from the system, including the water heater tank.
- Disconnect electrical, propane, and water connections.
- Remove the older heater and set the new one in place.
- Connect water, propane, and electrical.
- Test operation before securing the heater and re-sealing the exterior seams.
In addition to varying installation steps based on the heater manufacturer, some of these steps will require additional skills and safety precautions. For example, 120VAC power used for a previous gas/electric model won’t be used for a new tankless model. As a result, the wiring must be removed entirely or carefully terminated in a listed enclosure, and all conductors must be capped with listed wire nuts (separately) and wrapped with listed electrical tape. These are steps best left to a certified CW technician.
Read our complete guide to tankless water heater installation.
Do On-Demand Water Heaters Require Different Maintenance?
Despite the annual descaling requirement, some would argue that tankless RV water heaters require less maintenance because they don’t have an anode rod, and you won’t need a tank rinser to remove debris or sediments that settle in the bottom of a tank. However, you must still perform seasonal maintenance like fresh water system sanitization.
Additionally, winterizing a tankless water heater differs significantly from the winterization procedures required for tank-based designs. Winterizing and dewinterizing requirements for tankless heaters vary between manufacturers, but a commonality between them all is that a basic winterization (draining the water and blowing out the lines with air) will not be satisfactory to protect the heater from freeze damage. Winterizing with RV antifreeze is recommended. Always follow the precise directions for your specific tankless system when preparing for freezing weather.
Your RV water heater is only a part of your entire fresh water system. These resources might help you learn more about RV water systems.
- How Do RV Water Systems Work?
- Best RV Water Filtration Systems
- Hooking Up an RV Water Pressure Regulator and Filter
Do you have any questions about tankless water heater pros and cons for RV camping? Let us know in the comments below!
