Best Tiny House Water Heaters
Water heaters are a key appliance to living comfortably in any house. A nice hot shower does wonders for my mood, not to mention basic cleanliness. I don’t want to fret about hot water when relaxing in the shower.
When choosing a water heater for your tiny abode, considerations abound. Space? Power draw? Capabilities? Cost?
There just isn’t room for the standard 40 gallon home water heater. Could I fit a 20 gallon? What’s the basic difference between the conventional larger tank versions and the smaller, lighter tankless appliances?
Let’s consider the different kinds, compare size, cost, and performance so you can pick the best one for you.
Note: When picking a water heater for your tiny house or RV make sure it’s “certified” for use in this kind of structure. Otherwise the manufacturer might not honor the warranty.
Tankless or Tanked Water Heaters for you Tiny Home
Tankless water heaters are real space and weight savers in a tiny house. The good ones can cost over a thousand dollars. We’ll show several on this page, starting with the most well-liked down to inexpensive but workable models. You can follow the links and see more models and choices.
My Experience With A Tankless Water Heater
While visiting my son’s family in Italy I stayed in a tiny home that had a tankless water heater. It was built into the upper cabinet to the right of the sink in the kitchen.
Washing Dishes
When I do the dishes in my RV I use as little water as possible so I don’t use up my limited reserves and don’t fill my gray holding tank too fast. My RV has the basic six gallon water heater. The water is always hot and ready to go. I fill my washing basin about two inches. Rinsing involves a dribble, using as little water as possible. Normally this chore requires about 1.5 gallons of water.
Here in the Italian tiny house, the tankless water heater only warmed the water as needed and had no reserve tank. Each time I ran the faucet, the heater ignited and started heating the water. I needed to run what seemed like over gallons of water before it finally ran hot. When rinsing, I was done before any hot water showed up. I felt like I wasted a lot of cold water. Fortunately I wasn’t using my freshwater reserve or filling my gray-water tank.
Taking a Shower
Taking a shower was a little better, but I did need to run the water for quite some time before any hot water reached the shower. Again, that would not work for an RV or off-grid setup with limited supply. At first the water pressure was fine, but the water heater quickly throttled the pressure back to allow only the water volume it could heat. This was barely a trickle. I could take a shower but I wasn’t excited about the experience.
For my lifestyle I’m figuring I’d rather have a six to 20 gallon tank water heater.
Keep in mind your installation constraints
Will you be living in a cold climate like the mountains of Colorado? If so, you must locate your water heater inside your tiny house to keep it from freezing. If using propane, we also recommend a propane tank heating blanket be used to ensure constant gas flow even in cold temps. They can be ordered thru this link.
The starting temperature of your water
In some Texas cities, municipal water comes out of the ground hot. They bury their water lines just under the surface because there is no risk of freezing and the sun heats the ground. I always wondered why my sister from Texas would rush into my Colorado home and take a big drink of water from the kitchen faucet with a big, “Ahhhh.” Colorado water comes out of the tap refreshingly cold. So cold a tankless water heater might not have what it takes to heat it enough for a comfortable shower.
When buying a tankless water heater pay close attention to the amount it will raise the water temperature. If you’re starting with 35° water and the water heater can only raise the temp twenty-six degrees, your hot water will only reach a max 61°. Brrrrr.
One solution: Adding an in-house water tank will allow the water to pre-heat to room temperature before going thru the tankless water heater. That might be enough.
- You might prefer adding a small tank water heater like five or ten gallons if you have room.
- The Eccotemp EM-7.0 Mini Storage Tank Water Heater holds seven gallons.
Power Availability
Electric water heaters, whether tanked or tankless, usually require huge amounts of power.
- Will you be in an RV park that offers 50 amp service or only 30 amp service?
- Do they charge more for 50 amp service?
- Will your tiny house be wired for 220 volts or just 110 volts?
- Will you be off-grid on solar panels?
Propane-Powered Tankless Water Heaters
Propane tankless water heaters are a great choice for off-grid applications because they require very little electricity.
My favorite is this PRECISION TEMP RV 550 NSP WATER HEATER
The only floor-vented, four season, tankless water heater for RVs, trailers, tiny houses, cabins, or park models. There’s a bunch of power packed into this little unit: 55,000 BTUs to be exact, making this unit the highest hot water output in the industry. Add the built-in freeze protection and this tankless water heater really delivers more than just hot water.
- Endless hot water, on-demand. Heats up in just 10 seconds.
- Capacity: 55,000 BTUs max input (88°F temperature rise / gal / minute)
- 16,000 BTUs min input (26°F temperature rise / gal / minute)
- Water Temperature: Infinitely adjustable.
- Designed specifically for RVs, bus conversions, trailers, tiny houses, and cabins.
- Conveniently vents through the floor without any sidewall penetration.
- Takes up half the space and weighs one third as much as a ten-gallon tank. 14″ square.
- No pilot light and very high efficiency. It will detect freezing temps in water lines and protect itself.
- Requires a little 12 volt electricity which a solar panel system can easily provide.
- Straightforward installation. Connects as easily as a propane grill.
- Cost is $1,290.00*.
Here is a step-by-step YouTube® installation video for this water heater.
Here’s a Great Tiny Home Water Heater Idea
All the performance and features of the PRECISION TEMP RV 550 NSP WATER HEATER PLUS hydronic home heating included. This is a no-brainer. It’s already making hot water. Lets use that hot water to heat the tiny house at the same time!
The Precision Temp TwinTemp Junior produces more hot water, has no tank to keep warm, and provides an endless supply of on-demand hot water – all while using 50% less propane than a traditional tank heater.
It’s a very small package. Just 20.5” wide x 16” deep x 14” high and weighs 65 lbs. See details about hydronic heat exchangers on this page of Tiny Life Consulting: Best Ways to Heat Your Tiny Home
Dual Source, Unlimited Heat
This little tankless water heater packs a big punch with a 55,000 BTU propane burner and up to 1500 watts of electrical power. The Precision Temp TwinTemp Junior can support up to six blowers, making this the perfect option for buses, RVs and tiny houses.
This is just the water heater. You’ll need additional parts to complete the hydronic heating system.
Here’s a Real Powerhouse Tankless Propane Water Heater
This Rinnai RL75iP Propane Tankless Hot Water Heater has a powerful 7.5 gallon per minute flow rate.
It’s available in many forms including indoor or outdoor, natural gas or propane. Even models with 11 GPM flow rate.
This beast can handle all the faucets in your house at the same time.
Rinnai’s high-efficiency indoor tankless water heater models offer the most advanced technology with comfort and value. Unlike tank heaters which accumulate rusty sediments, this RL75iP compact tankless water heater has a longer lifespan, since water is heated on demand only, which saves on energy costs. Rinnai products provide peace of mind with warranties that surpass the competition.
This unit is certified for use in mobile homes so the warranty should be honored when used in a tiny house.
ECOTEMP i12 LP Tankless Propane Water Heater
(shown here) is a propane-powered tankless water heater that sells for for $399.00*. This bundle comes with a horizontal stainless steel vent kit, ready to install, and with its 120-volt UL listed power cord powering the internal exhaust fan and digital display. It only pulls about 2 watts idle and 1.07 amps during operation, making it an ideal energy-efficient appliance. It has an impressive flow rate of 4 GPM and can raise the water temperature 38 degrees.
Electric Tankless Water Heaters
Electric tankless hot water heaters can be real energy guzzlers. Most require a 50 amp, 240 volt electrical system which reduces your parking options in RV parks and other places.
The ECCOTEMP SmartHome 27 kW electric tankless water heater is rated at 4.5 GPM (gallons per minute) with a temperature range of 86-131 degrees Fahrenheit. This model provides hot water for up to three applications simultaneously. The SHiE27 requires a 240 volt electric service with a ridiculous amp draw of 113 amps. It costs $449.00* and looks just like the LP version shown here without the big vent at the top.
The Largest Electric Tankless Water Heater That Would Work In an RV
A 50 amp RV has a limit of (wait for it) 50 amps. Actually, you get two 50 amp circuits at 120 volts or 50 amps total at 240 volts. Looking at the current draw of the unit above you can see it would never work in an RV. Even the smallest electric water heater I can find, the Rheem, RTEX-04T, that is capable of heating just 0.9 gallons/minute requires 120 volts and a 30 amp breaker all it’s own.
It could work if you are not using anything else at the moment.
RV Tankless On Demand Water Heater
If your old RV water heater is on its last legs, or you feel like making an upgrade to your RV water system, this tankless water heater is a perfect choice. This tankless water heater provides you with a steady stream of hot water that you can use whenever you need, without wasting time waiting for a water tank to warm up. This unit is simple to operate and provides you with a great degree of convenience during your travels.
All you have to do is adjust the temperature and press go to get the hot water you desire!
This model is branded for RecPro but it’s made by Fogatti. These tankless, on demand, water heaters easily replace an RV’s existing 6 or 10 gallon water heater.
It is 60,000 BTU. On sale for $439.95* and comes with a black or white door.
If the temperature of the water flowing into the water heater is less than 43°F or higher than 90°, the water heater will not heat the water. If the water in the pipes is colder than 43°, it is recommended to use tank and tubing heater pads to heat the water before it reaches the water heater.
At higher altitudes, this unit will have two problems: the thermal efficiency will decrease and the power will be lost, and the insufficient combustion will lead to worse combustion conditions, substandard combustion emissions, or abnormal ignition. Above 4,000 ft elevation, this unit will lose 4% of its BTU for every 1,000 ft above this height.
A frost protection function is also integrated into the tankless water heater. If the temperature of the water in the pipe gets down to 43°F or lower, the heater will then start running in order to warm it up. Once the water reaches 90°F, it will shut off. It includes a full function remote control.
Fogatti makes a good range of tankless, on demand, water heaters available from Amazon.
Storage Tank Water Heaters for Tiny Homes
Rheem is a basic electric tanked water heater. They have sizes from 2 to 30 gallons. You’ll probably find them in stock at The Home Depot, but you may have to special-order the smaller models.
The Rheem Performance 10 Gal. Electric Point-of-Use Water Heater has a space-saving design that’s ideal for installations in tight spaces, and can supply a quick source of hot water for a single application. The heater includes a 2,000-watt element and a factory-installed temperature and pressure relief valve. This point-of-use heater requires a 120-volt electrical source for installation and can be mounted on a wall. This model has a 6-year limited tank and parts warranty, plus a 1-year in home labor warranty*.
This small tanked water heater is just 23″ high and 16″ in diameter, weighing just 46 lbs. It sells for $379.00* at The Home Depot.
The phrase “point-of-use” means they recommend it for one bathroom or other area located near that room. This would be perfect for a tiny home, as we are usually talking about one bathroom with a shower, sink, and one kitchen faucet. Assuming the home would have only two occupants, it should be enough. They do have 15, 20, and 30 gallon models, but they take up a lot of room and are very heavy.
ECCOTEMP EM 2.5 MINI STORAGE TANK WATER HEATER
The Eccotemp Mini Tank 2.5 water heater is a point-of-use mini-tank water heater, capable of holding 2.5 gallons. It’s designed to supply instant hot water on demand to any faucet without long hot water pipe runs. Your stand-alone sink or faucet instantaneous receives hot water without wait. It requires regular 110 volt power and uses just 1440 watts. Size is 12″ x 11″ x 20″.
This tiny water heater does have a quick recovery time, but 2.5 gallons would not be adequate for my shower needs. It would work great for the kitchen sink.
This seven gallon unit would work for a fast shower
The Eccotemp EM-7.0 Mini Storage Tank Water Heater is the seven-gallon version and sells for $229.99*. Dimensions: 17.25″ H x 14.25″ W x 17.25″ D. Plugs in just as easily and has the same power consumption.
Solar Powered Water Heater System
Split Tank High Pressure Solar Water Heater System
I’m wonderfully surprised at this solar powered water heater kit from Duda Solar. This Weather Resistant Closed Loop System OG-100 is SRCC Certified and eligible for 30% Government Tax Rebate.
This Solar System Includes: Duda Solar 14mm heat Pipe Solar Water Collector(s) 45° Stand, Food-grade stainless steel solar water storage tank, Working Station (circulation pump, controller, expansion tank, pressure gauge, pressure relief valve, tempering valve), Automatic Air Vent (for purging air from top-most portion of the system) food-grade inhibited propylene glycol, Thermostatic mixing valve (for prevention of scalding), Submersible Water pump (for initial air purge/charging of fluid into system).
There are 11 tank sizes available. The 200 liter, dual coil model is $3,393.51* at WalMart. Click image to see details.
Replacement Parts for your RV’s Heater
If your RV water heater has failed, The Mobile Home Parts Store carries a large array of replacement parts. Water tank heating elements, thermocouplers, and thermostats…the parts that fail the most can be easily replaced. This might be a cost-effective alternative to an entire water heater replacement.
Off-Grid Water Heating with Wood
water heater attached to wood stove from Humble Homes
Heating water with wood, off-grid will require a clever plumbing system of your own design. Tiny Life Consulting has a separate page dedicated to off-grid water heating with wood.