Best tankless water heater for a tiny home: Our Top 5 Picks!

Even if you’re drastically downsizing your home, you still want to enjoy the creature comforts of readily available hot water. With other living space sacrifices,…

Brass hot water tap in a bathtub

Even if you’re drastically downsizing your home, you still want to enjoy the creature comforts of readily available hot water. With other living space sacrifices, it’s crucial to get the essentials right.

Getting the best tankless water heater for a tiny home is definitely an essential.

Enjoying running hot water whenever the need arises makes small space living feel luxurious. And what’s more extravagant than an instant, endless source of it?

That’s the beauty of the best tankless water heaters. They offer on-demand hot water in a small space friendly size. 

When it came to choosing our tiny house water heater, our primary concern was the cost. Through friends at a Habitat ReStore, we scored a free whole house tankless water heater. My boyfriend and I were thrilled. 

Unfortunately, we didn’t realize it required a large-capacity propane tank–too big and too heavy for our little 20-foot tiny house trailer. As a result, we replaced it with a smaller, more efficient model.

Lesson learned. You can’t skimp on research!

With everything in a tiny house build, you need to assess your needs thoroughly before making any final decisions. This is especially true for big-ticket appliance purchase like the best tankless water heater for a tiny home.

That’s why I put together this helpful guide for choosing the best tankless water heater for a tiny home. Let’s get started!

*This post may contain affiliate links. Please read our disclosure policy for more info.

The best 5 tankless water heaters for a tiny house comparison chart

To kickstart your tiny house water heater search, take a look at this quick-reference comparison chart of the top options. For a better understanding of which is right for you, keep scrolling for product details and breakdown of pros & cons.

Eccotemp FVI12-LP
  • Dimensions: 15.25 x 6 x 24.75 inches 
  • Weight: 33 pounds
  • Power Source: Propane
  • Flow Rate: 3.6 GPM
  • Off-grid friendly
  • Easy to install
  • Only needs minimum water flow to turn on the heater
  • Very quiet
  • Uses minimal propane
  • Inexpensive
  • Small size
  • Internal exhaust fan and digital display requires a little electrical power
  • Getting the water temperature right can require multiple adjustments
  • Limited temperature control
  • Can easily freeze if not kept in warm enough indoor space; requires winterization for outdoor installation

This budget-friendly Eccotemp propane tankless model is an all-round excellent tiny house water heater. While it’s not overly fancy, it is cost, size, and energy-efficient. 

Due to its compact dimensions, the Eccotemp FVI12 is small space friendly tiny house tankless water heater. Additionally, it can be used with just a 20-pound propane tank, or up to 100-pound size. 

A horizontal vent kit is included, allowing for easy indoor installation within insulated walls. Unlike outdoor mounted models, there is less chance of freezing in the cold months.

Simplicity is often the name of the game when it comes to tiny house living. So with that in mind, I can appreciate the minimal bells and whistles of this model. 

It is a manual water heater, meaning both the water pressure and gas regulation must be adjusted via the knobs on the front of the Eccotemp FVI12.

This tiny house water heater is rated for running two fixtures, simultaneously, like a sink and shower. 

Based on personal experience with an earlier version of this Eccotemp model, that doesn’t always hold up. The drop in pressure from dual concurrent usage can result in shocking drops in the water temperature. There’s nothing worse than an unexpected icy cold shower! 

Avoid this problem by adjusting the gas flow. However, doing so at the moment is inconvenient. Fortunately, in a tiny house, it’s not often that you need to run two fixtures at the same time, especially if you live by yourself.

Just remember, if you move your tiny house to a new parking spot, you’ll need to make adjustments to your Eccotemp FVI12 to maintain a cozy hot water temperature. 

Changes in elevation, temperature, and water pressure from each new water connection require you to readjust both the water flow and gas regulator on this manual tiny house tankless water heater. And when the seasons change, you’ll more than likely adjust again as well.

Over the last several years, we have moved our tiny home many times to various climates across the United States. Happy to report our Eccotemp tankless water heater has adapted well, as long as we remember to winterize properly!

Now you see why the Eccotemp is on our list of best tankless water heaters for a tiny home!

Don’t forget the appliances! Check out this list of awesome essential appliances perfect for tiny home living.

Rheem RTEX-11
  • Dimensions: 4” x 9” x 13” inches
  • Weight: 7 pounds
  • Power Source: Electric
  • Flow Rate: 2.69 GPM
  • Inexpensive
  • Super compact and lightweight
  • 5-year limited warranty
  • Light-up digital thermostat
  • Self-modulating power control
  • Easy install with basic plumbing and electrical knowledge
  • Works well with low flow showerhead
  • High power draw for a tiny house; not ideal for solar-powered homes
  • Requires 50 amp breaker
  • Doesn’t work well with high water pressure; it only works with low flow showerhead
  • Requires extra parts for installation

Do you prefer not to use propane? If so, you definitely want to consider this electric tankless water heater, second on our list for the best tankless water heater for a tiny home.

Keep in mind; this is not off-grid friendly. Your tiny house must be wired for 50 amp service to run the Rheem RTEX-11.

Despite its high power requirements, the Rheem’s teeny dimensions provide maximum flexibility for installation in tight spaces in any tiny home. 

A significant benefit of this best electric tankless water heater for a tiny home is that it doesn’t require any venting. So it can be safely installed indoors with no need to cut a hole through your wall! 

And even better, it is self-modulating. That means at low flow rates, at just 0.25 GPM, the Rheem can activate and regulate the energy consumption based on the temperature of the incoming water for maximum efficiency. Ultimately, it requires less monitoring.

If you’re in the process of building a tiny house on wheels, check out this guide to choosing the perfect tiny house trailer.

Eccotemp i12-LP
  • Dimensions: 13.7 x 25 x 5 inches
  • Weight: 28.9 pounds
  • Power Source: Propane
  • Flow Rate: 4 GPM
  • Sleek design
  • Off-grid friendly; very low power draw
  • Fully automated, self-modulated
  • Digital thermostat
  • Only needs minimum water flow to turn on the heater
  • Can easily run both showers and sink faucet simultaneously
  • Uses very minimal propane
  • Easy to install
  • Inexpensive
  • Space-saving size
  • Fairly quiet
  • Heats up quickly
  • Requires extra fittings and hose for installation
  • Hard to find compatible vent fittings
  • Recommended to mount in a storage closet to reduce sound
  • Freezes easily; needs to be winterized
  • If vertical venting is desired, an expensive extra installation kit is needed

Next on our list for best tankless water heater for a tiny home – another model from Eccotemp – is their i12-LP model. It combines tried-and-true top features with cutting-edge technology in a sleek, stylish package. 

This is a fully automated water heater. Use the LED display to adjust it to your desired temperature easily. Also, it measures GPM (Gallons Per Minute), aka flow rate.

Thanks to the Eccotemp i12-LP’s advanced low-flow ignition technology, it maximizes uninterrupted hot water, avoiding cold spots.

Additionally, it is aided by an expansive 77-degree Fahrenheit temperature rise at 1.5 GPM and 35-40 degrees Fahrenheit temperature rise when operating at a flow rate of 4 GPM.

Though it runs off propane, this model skips the pilot light. Instead, it uses a safe electronic ignition system. And to take safety to the next level, the Eccotemp i12-LP incorporates child-lock technology. 

Camplux 16L
  • Dimensions: 17.32 x 7.87 x 27.56 inches
  • Weight: 36 pounds
  • Power Source: Propane
  • Flow Rate: 4.22 GPM
  • Straight-forward, simple installation
  • Easy to use
  • Off-grid friendly
  • Uses very little propane
  • Good customer service
  • No electricity required except 2D batteries
  • Bulkier than other portable water heaters
  • Showerhead supply hose very short
  • Even with anti-freeze protection, needs winterizing if not in use
  • Must be kept out of the rain
  • Lacks clear adjustment instructions

Depending on your tiny home lifestyle, a little added flexibility might go a long way. That’s why the Camplux 16L Outdoor Portable Tankless Water Heater for a tiny home is just a great option.

The Camplux 16L can be easily mounted or relocated outside. And if you love outdoor showers, you can use the included shower head attachment to cool off or clean up. Nevertheless, indoor installation is possible, if properly ventilated. 

While portable, the Camplux 16L is capable of a small residential flow rate capacity. 

Perhaps its best aspects are the advanced safety features— overheating, anti-freezing, flame failure, dry combustion, low water flow, and high water pressure protections.

Even with these built-in technologies, manual adjustment still is needed to find the ideal balance of water pressure and gas regulation.

Tiny house furniture is another big essential you don’t want to forget! Check our list of perfect tiny house furniture.

Rinnai RU130iP
  • Dimensions: 18.5 x 11.45 x 31.3 inches
  • Weight: 62 pounds
  • Power Source: Propane
  • Flow Rate: 7 GPM
  • Excellent energy saver
  • Easy to vent
  • Warm, not hot exhaust
  • Ultra-low NOx
  • Freeze protection
  • High altitude approved
  • Mobile home certified
  • 15-year warranty for 12,000 hours on heat exchanger and 5-year parts warranty
  • Whole house capable, up to 4 simultaneous fixtures
  • Expensive
  • Professional installation recommended
  • Without a return line or recirculation, can take a long time (up to 1 minute) for the hot water to reach the faucets
  • Larger propane tank recommended for best results
  • Higher electrical pull, up to 145 Watts for freeze protection

This is truly a residential capable tankless option. Despite its large capacity, the RU130iP tankless water heater for a tiny home is only the size of a small suitcase. Though, it is about twice as heavy as the other tiny house water heaters shown above.

Do you want to put down roots? This Rianni RU130iP model is an ideal water heater for a small house. Impressively, it handles up to four fixtures simultaneously. 

Additionally, unlike the other best tankless water heaters for a tiny home discussed above, you likely want installation help from a professional.

But the Rianni makes up for it by offering truly endless hot water supply with double the water flow capacity, up to 7 GPM. 

When the groundwater temperature drops significantly in the winter, so does the water flow. Fortunately, this only brings the simultaneous use down to two fixtures–the high end of the other tankless water heaters reviewed here.

Because the RU130iP is a condensing tankless water heater, it is exceptionally energy-efficient. It recycles the hot exhaust to heat the water further, resulting in much cooler exhaust. 

Further, the two-step combustion process significantly reduces NOx (nitrogen oxide gasses) emissions.

It might be worthwhile to add the Circ-Logic external pump (separate purchase required) to reduce wait time for hot water. This allows you to enjoy the on-demand re-circulation of hot water on a schedule. 

For an additional $800, you can purchase a Rianni model with this feature built-in. But based on customer reviews, the internal function comes with complications and can still require an additional accessory. 

Ultimately, if you want recirculation, it’s probably worth buying the approximately $100-$150 external pump with multiple compatible options available.

Need help finding the perfect toilet for your tiny house? We’ve got you covered!

Why you might want the best tankless water heater for a tiny home

Tankless water heater for a tiny home

Readily available hot water creates a homey feel. Without it, you might as well be camping. And that’s not what tiny home living is about. 

Minimizing your house size and belongings is more about living efficiently, creating more personal freedom without skimping on the comforts of home.

Accordingly, tankless water heaters make a very worthwhile option for tiny houses. 

They offer almost endless on-demand hot water, in a space and energy-efficient package, what’s not to love about that! 

How a tankless water heater works

Connect your potable hose to it, add electricity, propane, or natural gas. Then hot water directly moves to your fixtures. This eliminates any need to hold the hot water in a storage tank. Moreover, energy efficiency is greatly improved by eliminating heat loss from standing water.

Small and medium-size tiny house tankless water heaters use hardly any propane. For instance, with our Eccotemp model, we can easily go two to two and half months on one 20 pound propane tank–and that includes daily use of our gas range.

Importantly, you can easily find budget-friendly tankless options. 

Conversely, with small storage tank water heaters, they cost as much or more as their tankless counterparts. Further, their hot water supply is minimal. Then you can be stuck waiting up to an hour for it to refill. Ugh! I’m too impatient for that.

With these factors in mind, that’s why a tankless water heater is a worthwhile investment for a tiny home. Enjoy the luxury of always available hot water that can easily tuck away in a corner or a slim storage compartment.

When trying to decide on the best tankless water heater for a tiny home, you need to contemplate these key considerations:

Power source and availability

Will you be entirely solar-powered, or do you plan to have consistent access to gas-generator or shore power? Is your tiny house wired for 30 or 50 amp service? 

The most budget-friendly choice is an electric tankless water heater for a tiny home.

Unfortunately, when it comes to 50-amp compatible options, there’s not much to choose from when it comes to a model with shower-ready water flow capacity. 

Though, options greatly expand for park models with 100-amp service or foundation-based small homes.

Propane tankless water heaters for a tiny house are, of course, the most off-grid friendly. However, they have a very low power draw that requires an electrical source–plug-in or battery powered.

Of note, propane options often are more pricey but also more powerful than their electrical counterparts.


The cost of installing the best tankless water heater for a tiny home is more than the unit itself. If you are not up for DIY installation or have a more complicated model, consider the cost of professional help. 

Factor in any needed extra parts, like fittings. And don’t forget to budget for winterization needs, especially essential for outdoor mounted units (pipe installation, heated tape, etc.).

Desired parking location(s)

Do you plan to put down roots in one area, or do you want the flexibility to relocate easily? Do you want to live in the mountains or a hot climate? 

Your tiny home location (region and elevation), combined with hot water usage needs, directly impacts a tankless water heater’s effectiveness. So choose wisely! 

First, you need to know your desired flow rate (GPM or gallons per minute). The number of fixtures or devices you want to run simultaneously dictates this measurement. 

Typical tiny house fixtures – average GPM – average temperature

Low-flow shower head – 2.5 GPM – 105 to 110 degrees
Kitchen sink – 1.5 GPM – 110 to 115 degrees
Bathroom sink – .05-1 GPM – 110 degrees

So if you want to shower and use the kitchen sink at the same time, you need a tankless water heater with 4+ GPM capability. But if you’re ok with not doing dishes while you shower, you can get away with a lower GPM.  

The flow rate works hand in hand with the required temperature rise.

Temperature rise is the difference between the temperature of the cold water entering it and the hot water exiting the water heater. 

To determine the needed temperature rise, simply subtract the desired hot water temperature from the incoming groundwater temperature.

In layman’s terms, if you want to take a cozy 105-degree shower and incoming water is 42 degrees, the required temperature rise is 63 degrees.

Confused? I totally understand. The reason the temperature rise matters is that your tiny house tankless water heater needs to reach the appropriate temperature. 

And, this number varies based on groundwater temps in different geographic regions. Refer to this US groundwater map to help you with your calculations.

Understanding the range needed based on the place(s) you want to put your tiny house will help you pick the ideal tankless water heater.

Let’s break down a simple real-world example based on the Eccotemp i12. Overall, it offers a 77-degree Fahrenheit temperature rise at 1.5 GPM, and 35-40 degree Fahrenheit temperature rise when operating at a flow rate of 4 GPM. 

A tiny house water heater needs a 63-degree rise to achieve an ideal shower temperature of 105 degrees, at 2.5 GPM, while at the northern region’s chilling 42-degree groundwater.

In conclusion, the Eccotemp i12 would work beautifully.

Tiny house water heater alternatives

Tiny home kitchen

Curious about alternative tiny house water heater options? Besides a tankless water heater for a tiny home, you can always opt for a tanked model.  

The significant benefit of a traditional storage water heater is its dependability. It’s less prone to erratic temperatures. Notably, they require more routine maintenance than their tankless counterparts.

A top-seller is the Bosch Tronic 3000 T Mini-Tank Water Heater. It’s a 7-gallon electric model that works with just 20-amp service. 

Bosch Tronic 3000 T
  • Dimensions : 17.5 W x 17.5 H x 14.5
  • Recovery Rate at 90°F Rise: 6.8 GPH
  • Water Pressure Range: 150 psi
  • Weight : 29.5 lbs
  • Electrical Requirements (Amp/Volts) : 12A / 120 V

A solar water heater is a sustainable alternative option for tiny homes. While the upfront expense can be quite pricey, over time, it can be exceptionally cost-effective.

It is distinctly separate from solar power systems providing electricity for your home. Instead, it utilizes a high-efficiency 2-part system–a storage tank and solar collector.

As you might imagine, consistent functionality is contingent on how much sunlight your property or parking spot receives. It’s a good idea to have some kind of backup, like a point-of-use tankless water heater.

This is well-suited as a water heater for a small house homestead, but not for a tiny house on wheels desiring easy relocation.

The Sunbank 40-Gallon Solar Water Heater Complete System is an exciting new option. Unlike other available models, it has no moving parts and does not require glycol or pumps.

Sunbank 40-Gallon Solar Water Heater Complete System
  • Product Dimensions : 68 x 48 x 60 inches
  • Item Weight : 180 pounds
  • Manufacturer : Sunbank Solar

Interested in more options for off grid living? Check out this off grid tiny house setup for inspiration.

Conclusion on the best tankless water heater for a tiny home

Of all the tiny house water heater choices, I recommend tankless as the best all-around option for simplicity, efficiency, and flexibility. 

Once you enjoy on-demand hot water, it’s hard to consider anything else. With frequent showers and daily dish-washing in my tiny home, I can’t imagine life without my tankless water heater.

I know shopping for the best tankless water heater for your tiny home can be overwhelming.

As you research available models, just remember to carefully consider size based on the factors covered in this article.

When in doubt, ask others about their selection and experience in tiny house Facebook groups.

No matter where you plan to roam or put down roots with your tiny home, you’ll be happy you invested in a tankless water heater. 

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One Comment

  1. Charles M Helmer says:

    Thanks for your article. Very informative.
    Do you have a relatively accurate figure for the daily electrical consumption in Watt hours of a propane fired tankless water heater for a tiny house . I am off grid and cant spare any electicity for parasitic loads (eg anti freeze protection in summer) . Its difficult to get these figures form manufactureres but it is a critical figure for off grid . Which are the “stingiest” brands froman electrical usage perspective.

    Thank you

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