Warm showers on cold, frigid mornings is something you never want to give up, no matter how much you might want to live off-grid. In a tiny house setting, a nice warm shower is one luxury that you can’t do away with, which is why tankless water heaters are so popular in the tiny house community.
With that perfect tankless water heater, you and your family can keep enjoying warm water no matter how cold it might be outside.
So what are the best tankless water heaters for tiny house homeowners? We’ve compiled a list of the top tiny house tankless water heaters on the market today, according to user reviews, personal experiences, and top selling units. These are:
- Rheem Heating Chamber RTEX-13
- EcoSmart ECO 27 Electric Tankless Water Heater
- Rinnai RL Series HE+ Tankless Hot Water Heater
- Atmor AT-910-27TP ThermoPro Electric Tankless Water Heater
- Takagi T-KJr2-IN-LP Indoor Tankless Water Heater
Below we go into each tankless water heater unit and explain their strengths and weaknesses, so you can decide exactly which one you need for your home.
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1) Rheem Heating Chamber RTEX-13
Who Should Buy It: Tiny house homeowners looking for something simple, affordable, and compact.
| Pros | Cons |
| Reliable water temperature control, with no mixture of cold and hot water | Some homeowners complain about leaking a few months after installation |
| Fast installation that makes owning this item a breeze | Not as heavy duty as more expensive tankless water heaters on the market |
The Rheem RTEX-13 240V Heating Chamber Residential Tankless Water Heater is the perfect no-nonsense water heater for tiny house homeowners just looking for that simple, affordable solution. Its compact shape means you can easily install it near its point of use, and in just 15 seconds you can enjoy hot water flowing from your shower.
With an installation time of just one hour and a maximum flow of 4 gallons per minute, the Rheem RTEX-13 is also quite simple to adjust and operate with its digital water temperature settings.
| Product | Rheem 240V Heating Chamber RTEX-13 Residential Tankless Water Heater |
| Manufacturer | Rheem |
| Weight | 4 lbs |
| Dimensions / Size | 4” x 9” x 13” |
| Average Amazon Score | 4.1 |
2) EcoSmart ECO 27 Electric Tankless Water Heater
Who Should Buy It: If you want to make sure that you really never run out of hot water in your tiny house for your entire family, the Eco 27 is the tankless water heater for you.
| Pros | Cons |
| The unit comes with a digital temperature control system that allows the homeowner to easily operate the unit and change the temperature settings to get their exact preference | The water temperature settings aren’t as precise and accurate as the digital control system indicates |
| The stainless steel and copper pieces are ideal for easy replacement, long-term durability, and sustained efficiency | Customer service of the company has had complaints about not honoring their warranty promises |
The EcoSmart ECO 27 is one of the largest water heaters in EcoSmart’s range of tankless water heaters, so if you’re looking for the EcoSmart brand and want to ensure power and performance for your residential use, the ECO 27 is what you need. No fiberglass insulation and pipe wrenches makes this unit easy to clean and maintain with just a Phillips screwdriver, making this one of the easiest electric models around.
One great feature of this unit is its self-modulating technology, meaning energy is only used when water is flowing, saving homeowners just about half of their energy costs for water heating in residential use. You can run two showers at the same time with the ECO 27, which promises an unlimited supply of hot water.
| Product | EcoSmart ECO 27 Electric Tankless Water Heater, 27 KW at 240 Volts, 112.5 Amps with Patented Self-Modulating Technology |
| Manufacturer | EcoSmart |
| Weight | 13.75 lbs |
| Dimensions / Size | 17” x 17” x 3.75” |
| Average Amazon Score | 4.1 |
3) Rinnai RL Series HE+ Tankless Hot Water Heater
Who Should Buy It: The best exterior tankless water heater on the market, with a variety of interesting features that make this unit feel like a must-have luxury item for any tiny home looking to heat water.
| Pros | Cons |
| Tons of nifty features that make it stand out from a crowd of tankless water heaters, such as pre-heating capabilities and WiFi connectivity | This is an exterior heater so it is installed outside the home, so make sure that you are looking for an exterior heater |
| Surprisingly uses almost half as much water as traditional tanks; this product is popular for its high water and energy efficiency |
This propane-powered tankless hot water heater is often described as the best tankless water heater for tiny homes on the market, and it’s hard to argue against it. The Rinnai RL Series HE+ RI75EP device is actually designed to supply hot water for a full-sized home, but still perfectly fits the energy and size requirements of tiny homes.
With 7.5 gallons per minute or GPM of hot water and various features – such as programming specific times when to pre-heat your water and the ability to connect it to your WiFi for easy accessibility – the Rinnai tankless water heater feels like a luxury item you can’t afford to miss in your tiny home.
| Product | Rinnai RL Series HE+ Tankless Hot Water Heater |
| Manufacturer | Rinnai |
| Weight | 43.6 lbs |
| Dimensions / Size | 14” x 9.6” x 24.3” |
| Average Amazon Score | 4.4 |
4) Atmor AT-910-27TP ThermoPro Electric Tankless Water Heater
Who Should Buy It: Tiny house homeowners looking for a strong, reliable, heavy-duty American product while still looking for something small and compact.
| Pros | Cons |
| 27,000 wattage, meaning the Atmor has tons of power to keep your water nice and heated even during the coldest months | Buyers are required to purchase a pressure relief device from Atmor to be installed with this water heater. These can be difficult to find and must be bought from Atmor itself |
| Tiny, easy, and compact. Installation is a no-brainer, so you need no professional to install |
At just 17 pounds and tucked into such a compact frame, the Atmor AT-910-27TP ThermoPro Electric Tankless Water Heater can be installed almost anywhere you might want, which is perfect for the size limitations of tiny homes. The small size also means that installation is simple and straightforward, so anyone who can read the instructions can safely install this in their home in no time at all. No need to call in a professional to install to help you heat water.
Atmor is a trusted US manufactured company, with many reviewers loving the reliability and durability of the AT-910-27TP water heater, which supplies extremely hot water flow even during the coldest winter months. At 27,000 watts, this device doesn’t cut any energy corners – you get exactly the water flow heating you need.
| Product | Atmor AT-910-27TP ThermoPro 27kW/240V Electric Tankless Water Heater, 5.1GPM 112.3 Amps |
| Manufacturer | Atmor |
| Weight | 17 lbs |
| Dimensions / Size | 17.4” x 5.2” x 13.4” |
| Average Amazon Score | 3.7 |
5) Takagi T-KJr2-IN-LP Indoor Tankless Water Heater
Who Should Buy It: Perfect for tiny house homes, as this model is the smallest in the Takagi line-up.
| Pros | Cons |
| Simple device with no fancy features. Relatively quiet compared to most water heaters while still producing the desired water heat | This device requires stainless steel single wall venting with direct ventilation to the outside |
| Cheap and affordable due to its small size, so you could save heating costs in a tiny house |
With a light, stylish, and modern compact design, the Takagi T-KJr2-IN-LP Indoor Tankless Water Heater can fit into any tiny house seamlessly through looks alone. Its small size makes it an easy and fast installation wherever you might want to place it. At 6.6 GPM (which might drop to around 3-5 GPM in colder areas), you will never run out of hot water in your tiny house, even if you’re running the shower and the sinks at the same time.
The Takagi has lower thermal efficiency and energy usage than other tankless water heaters, which makes it less than ideal for full-sized homes. But in a tiny house, the Takagi is a great and easy space-saving solution with its own digital temperature control.
| Product | Takagi T-KJr2-IN-LP Indoor Tankless Water Heater |
| Manufacturer | Takagi |
| Weight | 38 lbs |
| Dimensions / Size | 6.7” x 13.8” x 20.3” |
| Average Amazon Score | 4.1 |
Guide to Buying a Tiny House Tankless Water Heater
Why Tankless Instead of Traditional
While many tiny house homeowners are now opting to go tankless for their water heating needs rather than traditional, it is still important to understand why. Traditional water heaters come with their own water storage tank that must be maintained at a certain temperature.
This means that power needs are 24/7 for traditional water heaters, as they must keep the water at a certain temperature at all times. And for tiny house living, these energy needs can be difficult if not downright impossible to provide.
Tankless water heaters fit the needs of tiny homes much better – the compact and light design makes them easier for installation, and they only use energy when water is flowing, meaning you could save tons on your energy requirements.
Types of Power for Your Water Heater
- Electric: Electric models are cheaper devices, but more expensive daily energy heating costs, at about 4000 watts per hour. This can make electric water heaters difficult to power if you’re using an off-grid energy system. The only advantage of electric water heaters is their added safety, with no risk of a gas leak.
- Gas or Propane: Less affordable devices, but cheaper daily energy costs. Gas or propane water heaters can run on propane, natural gas, and sometimes both, giving you tons of flexibility for tiny house living.
- Solar: Solar water heaters might sound fancy, but they’re actually the most basic heating method available, using sunlight to keep your water warm. They are much less popular than other types of heaters, but also use zero energy aside from sunlight.
- Wood: Some tiny house homeowners like keeping it old school, and in this case, you would use a wood-fired water heater. This can either involve a wood fire heating a pot of water, or copper coils heated through convection methods.
Knowing the Difference Between Interior and Exterior Installation
While some tankless water heaters can be installed wherever you want, others can only be specifically installed in the interior or the exterior of your home, and knowing what you want before you purchase is essential, or else you might end up getting a tankless water heater placed in a spot it can’t handle.
Exterior tankless water heaters might seem preferable, as they allow you to save space inside of the home, but if your local climate is too cold then it will damage your device. If you are planning to go exterior, make sure that the device can survive the local temperatures of your area before purchasing it.
About Us
Hey, there! We're Ivan and Manuela from Croatia, and we're crazy about tiny houses. We don't own one (yet).
This website is a result of our passion to share all the knowledge, photos, tips and tricks that we were able to learn while studying everything possible about the tiny house movement.