Which Tiny House Water Heater Should I Buy? Advice From A Full Time Tiny Houser

There’s a lot to love about my tiny house but, surprisingly, one of my favorite features is the hot water heater. That might sound a bit strange, but it’s mostly because it took me over seven years of trial and error to find the perfect fit.

I felt a little like Goldilocks at first. The first water heater was too hot while the next few were way too cold. But once I came across my current favorite, I knew there was no going back. So, are you ready to find out which tiny house water heater took the cake? Let’s jump straight in.

My Top 5 Tiny House Hot Water Heaters:

• Rinnai V53DeP
• Precision Temp RV-550
• Ecotemp L5
• Eccotemp L10
• Rheem RTEX-11

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	Rinnai V53DeP	Precision Temp RV-550	Eco Temp L5	Eco Temp L10	Rheem RTEX-11
My Ranking
Flow Rate	5.3 GPM	1.5 GPM	1.5 GPM	2.9 GPM	2.68 GPM
Energy Type	Propane/Natural Gas	Propane	Propane	Propane	Propane
Why Consider	Best performance and build quality	Good option for 12-volt systems	Great for outdoor showers	Budget friendly with good functionality	Super compact
Who Is It Best For	General and off-grid water heating	RVs	Weekend cabins and seasonal outdoor showers	Budget-minded tiny house folks	Those on the grid
Price	$550	$1,195	$129	$349	$275
	BUY NOW	BUY NOW	BUY NOW	BUY NOW	BUY NOW

Rinnai V53DeP: Best High-Capacity Tankless Water Heater

Rinnai V53DeP
My Ranking
Flow Rate	5.3 GPM
Energy Type	Propane or Natural Gas
Why Consider	Best power and build quality
Who Is It Best For	General and off-grid water heating
Price	$550
BUY NOW

I mentioned that of all the tiny house hot water heaters I’ve had over the years, there was one that stood out, and this was it. Rinnai has been in the tiny house tankless water heater scene for a very long time. Way before most of us even heard of this company, they were building hot water heaters.

I think it’s very telling that every time a plumber has come to my house (not to fix the water heater), they always say something to the effect of “that’s a great choice” or “Rinnai is the best for tankless.” After using my V53 for close to five years, I have to emphatically agree.

You can order these units in a propane version (denoted by the P at the end of the model number) or in a natural gas version (N model). This is a direct vent style that is made to mount outside your tiny house, which is very important. Venting is a huge pain in a tiny house because you need to use such large ducting. It’s much easier to just mount it on the outside.

These units have freeze protection, and you can buy an optional dump valve for if the power goes out. This is the best option for an off-grid hot water heater that I’ve found.

I have the propane version because I find running on propane is easiest. I just have normal 20 pound propane tanks hooked up to it, and with that I can heat my water and cook on my stove (also propane) for about 2-3 months per tank.

At 5.3 gallons per minute (GPM), this will give you endless hot water — even if you have a shower going and two sinks. These units come in at around $550, and it’s money well spent. Rinnai units are built to a very high standard, in my experience.

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Rinnai V53DeP Pros And Cons

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Precision Temp RV-550: Overrated But Adequate

Precision Temp RV-550
My Ranking
Flow Rate	1.5 GPM
Energy Type	Propane
Why Consider	Good option for 12 volt systems
Who Is It Best For	RVs
Price	$1,195
BUY NOW

I put this one next because I know it’s a very popular water heater for tiny houses. However, I’ve had three of these now and each one of them was plagued with issues. At a price of $1,195, there is no excuse for it to not work well when it’s twice the price of the next-most-expensive competitor.

I’ve detailed why I don’t recommend this company for tiny home water heaters in this post. The biggest issue I had was when I received my first unit, I noticed an odd rattle inside it. I decided to open it up, only to find the internal vent loose, so all the carbon monoxide created by the unit would have blown right into my house instead of venting outside. That could have killed me.

Now, there are some reasons that people like these units. First off, it’s designed for RVs and campers, so it can handle lower flow rates than some of the competitors. At 1.5 GPM this will be able to run a low-flow shower head or a sink, but not really both at once.

Another thing to know is that this unit doesn’t have the same BTUs, a measure of heat output, as the other units. My Rinnai has a max BTU output of 120,000 BTUs, while the RV-550 only has 55,000 BTUs. That’s just under half the BTUs — which translates to half of the power. What that means in practical terms is that even in my mild North Carolina winters, the best the RV-550 could do was make my water warm, but not hot.

To be fair, Precision Temp is very transparent about this, but I didn’t understand what 55,000 BTUs really meant practically even after reviewing their site and literature.

So to sum up, it’s twice the price, half the BTUs, and, in my experience, the workmanship on these units is not acceptable.

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Precision Temp RV-550 Pros And Cons

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Eccotemp L5: Reliable Outdoor Performance On A Budget

Eco Temp L5
My Ranking
Flow Rate	1.5 GPM
Energy Type	Propane
Why Consider	Great for outdoor showers
Who Is It Best For	Weekend cabins and seasonal outdoor showers
Price	$129
BUY NOW

This is another very popular tiny house tankless water heater that many people consider when thinking about building a tiny house. I actually recommend this one to a lot of people — in very specific circumstances. I think if you use this hot water heater in the right situation, you’ll love it. But if you try to do something it’s not really meant for, you’ll be disappointed.

This hot water heater is designed for those who need hot water in more remote or austere conditions: your weekend rustic cabin, going camping, setting up a temporary shower, or if you need hot water in some remote part of your property.

This unit is designed to be used seasonally with less-than-permeant usage. What that means is if you have this as your main tiny house hot water heater, you’re going to be disappointed. It’s an attractive option at $129, but for everyday use, you’ll want something more robust.

What I use this for is my outdoor shower. I’ve used the L5 for years now as an outdoor shower, and it’s amazing for that. I have a simple platform I stand on, and I mount this unit on a single screw on a vertical post. I connect my garden hose and a 20 pound propane tank, and in literally 2 minutes I am taking a nice, hot shower.

For the price, this unit is a great buy. One downside I’ve found is that if there is any real wind, the unit’s flame will go out. You can do some shielding around it, but because it is a direct vent unit, you need to keep it outside — never bring it inside!

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Eccotemp L5 Pros And Cons

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Eccotemp L10: Mid-Range Model For Everyday Outdoor Use

Eco Temp L10
My Ranking
Flow Rate	2.9 GPM
Energy Type	Propane
Why Consider	Budget friendly with good features
Who Is It Best For	Budget minded tiny house folks
Price	$349
BUY NOW

If you’ve considered the previous Eccotemp model but want something that’s going to be more reliable for your house in everyday use, this is a great option. The L10 is designed to be used in a house every day at 2.9 GPM, where the L5 is more for camping applications.

At $349, this strikes a very good balance of cost versus value. I’ll be upfront and say that this company is a lower-tier manufacturer from China relative to Rinnai, but I’ve found they do a good job for the price. While you can see the products are no frills, they perform where it matters.

The biggest difference between this one and the Rinnai is that the heat exchanger, the most important part of a water heater, on this model is made of less copper. Because they are less expensive than the high-quality copper found in the Rinnai, the Eccotemp’s cheaper alloys don’t deliver the same performance. You’re basically making a tradeoff: slightly lower output at a much lower price.

This one is also an outdoor-mounted version, so venting is a breeze. It also runs on propane, which I find to be the easiest fuel source.

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Eccotemp L10 Pros And Cons

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Rheem RTEX-11: Compact Electric Powerhouse

Rheem RTEX-11
My Ranking
Flow Rate	2.68 GPM
Energy Type	Propane
Why Consider	Super compact
Who Is It Best For	For those living on the grid
Price	$275
BUY NOW

The last option here is the Rheem RTEX-11, and this is one that I looked at seriously for my tiny house. The biggest benefit of this unit is that it’s so compact — only 8 inches wide x 13 inches tall x 4 inches thick. That’s about a tenth the size of all the others on this list.

The reason for that is that Rheem units use electricity to heat your water. This unit comes in 8, 11, and 13 kilowatt (KW) versions. The 8 KW version might be a little too small for your needs, while the 11 KW version is usually perfect for tiny houses at a flow rate of 2.68 GPM. One benefit to electric models is that you don’t have to vent, so this unit can be tucked under your counters, back in a corner of your cabinets.

If I was able to be on the grid, this would be the unit I’d have gone with. A lot of the plumbers I talked with said Rinnai was their personal favorite, but Rheem was a close second. Being that I live off the grid, I have to heat my water with propane.

It is also hard to beat the price at $275. With this high quality of a unit in such a small housing, this is a great hot water heater option for your tiny house.

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Rheem RTEX-11 Pros And Cons

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Tiny House Water Heater Buying Guide

Choosing a hot water heater for your tiny house is an important decision because it will impact your designs, utility connections, and whether you can go off grid. Hot water is also one of those hallmarks of civilization if you ask me. Nothing is better than taking a long, hot shower.

Here are some things to think about when choosing a tiny house water heater:

Tankless Vs. Traditional

Let me make this simple: when it comes to tiny house water heaters, you want tankless. Traditional hot water heaters have large tanks that hold water and heat it constantly. Not only is this pretty inefficient because you’re heating water when you aren’t using it (which is most of the time), but these are also very heavy.

Water is about 8.2 pounds per gallon, and in a tiny house, every ounce matters. Having a traditional water heater means you need a much bigger trailer, and that adds up fast. Along with weight, traditional water heaters are also much larger, which isn’t ideal in such a small space. Tankless hot water heaters typically take up a lot less space, making them easy to mount in a corner under a cabinet or on the outside of your house.

Tankless hot water heaters are also a huge step up over tanked hot water heaters because you never run out of hot water. Traditional models aren’t that much cheaper either, so the cost versus benefit of tankless is a clear winner.

If you want to be off the grid, a tankless water heater running off of propane or natural gas is really the only practical method — unless you use a wood stove, which is a real pain.

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Indoor Vs. Outdoor Installations

This is another simple decision: outdoor installation is ideal. Indoor-mounted hot water heaters require ventilation with vent tubes. These tubes are pretty hefty and mean you have to cut a large hole in your wall to vent properly.

Compare this to an outdoor installation that you can vent right outside with no extra work involved. Mine mounted in about 5 minutes, and the vent was already built into my unit, so I couldn’t screw it up if I tried.

Indoor units can be tricky to vent, requiring certain offsets and maximum vent lengths that are shorted by each elbow you put in the vent tube. The only time I’d opt for an indoor-mounted unit is if I lived in a place that was prone to super cold temperatures.

Between the ease of installation and the fact that you aren’t taking up any indoor space, I’d suggest an outdoor-mounted tankless hot water heater.

Energy Source: Propane Vs. Natural Gas Vs. Electric

This really comes down to whether you want to be off the grid or not. If you’re going to be off the grid or might be some day, propane or natural gas is the way to go.

If you’re going to be living in one spot and can have a gas delivery truck fill up a larger tank, natural gas is most likely the way to go. If you’re on the go or just getting your own gas, I’d suggest propane because it’s more readily available.

If you’re on the grid, the electric models from Rheem are really nice and super compact, plus there are no gas lines to mess with — a bonus in my book since running gas lines can be dangerous and always makes me nervous.

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Off-Grid Hot Water Heating

Much to my point above, if you’re going to be off the grid, a gas option is really your best bet. I crunched the numbers on what it would cost to add additional solar panels to my system to offset the need for propane and it was going to cost me an additional $15,000 just to have an electric hot water heater.

I like to keep in mind that my house is totally off the grid, running on solar power, so I’m already treading very lightly on the earth. If I use 80 pounds of propane per year, I’m still much better than most out there.

Many people ask about skipping the tiny home water heater and heating their home and water with a wood stove instead, but my advice is to avoid this unless you already live with a wood stove as your primary source of heat. Wood stoves are often romanticized by people when designing their tiny house. The reality is that you’ll be waking up to a pretty cold house each morning. Hot water won’t be ready for at least an hour, and a wood stove doesn’t heat much water to begin with.

Go with a gas option for heating water off the grid — you’ll thank me later.

Hot Water Heater Venting

If you have a hot water heater that is installed inside your tiny house, you’ll need to vent it if it uses any form of combustion. Venting isn’t something to take lightly because there are so many ways to do it wrong, and mistakes can lead to deadly results.

A vent is usually metal ducting that captures fumes and exhaust from your hot water heater and directs them outside. It may also have an air inlet to bring in fresh air for combustion.

Venting usually has a lot of technical parameters from the manufacturer around how far the vent tube can stretch, the type of ducting you use, offsets or clearances from combustible materials, and other technical bits to make sure you do it right.

I prefer to have outdoor-mounted tiny house water heaters because they avoid all the headaches and potential dangers posed by venting. If you do decide to use a unit that requires venting, follow the manufacturer’s directions carefully.

Freeze Prevention Water Heater Features

Another area where you can go wrong with tiny house water heaters is having your pipes freeze. Most units today have some sort of frost prevention mechanisms — usually a heating coil for outdoor-mounted units. Indoor-mounted units don’t really have to worry about this.

If you live in a very cold climate, indoor-mounted options might make a lot of sense, even if it’s an indoor mount in an unheated enclosure that’s been insulated well. The best advice I’d say is to follow local wisdom on how to prevent freezing.

You want to try to minimize the PEX lines outside your heated space and, where possible, insulate and apply heating strip tape to them for frost prevention.

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Do I Need A Water Tank In My Tiny House?

Because they require less water than a full-size house, a tiny house water tank isn’t necessary. However, if you live in a tiny home on wheels and travel often, it might be worth considering one. Water tanks provide reliable access to clean water and give you more flexibility and independence. However, those of you connected to city water or living off the grid should probably skip the tank and opt for a tankless tiny house water heater instead.

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What Size Water Heater Do I Need?

For a tiny home with one or two people, 2 to 5 GPM tankless tiny house water heaters are enough to supply the home with continuous hot water. If you’re looking for tanked water heaters, the general rule is between 10-15 gallons per person.

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Tiny House Water Heaters FAQs

Water heaters for tiny houses require some unique considerations, and it’s easy to feel overwhelmed when you’re first starting out. So from sizing and capabilities to installation and energy use, here are the answers to some of your most frequently asked questions — no plumbing experience needed.

How Much Space Does A Tiny Home Water Heater Need?

The amount of space your water heater will need depends on the particular model. Some are small enough to tuck under the kitchen sink, while others need to be wall mounted. Overall though, tankless tiny house water heaters require less space than tank models and are much better suited to tiny life.

What Are The Most Common Problems With Water Heaters?

Even the most reliable tiny home water heater can fail occasionally. As with their full-size counterparts, some of the most common issues you may run into with your tiny house water heater include:

• Inconsistent water temperatures
• Limited flow rates
• Hard water and sedimentary buildup
• Leaking

Can You Install A Water Heater Yourself Or Do You Need To Hire A Professional?

If you have some experience under your belt and are working with an easy-to-install tiny home water heater, DIY installation is doable. That said, it’s almost always better to hire a licensed professional — especially if you’re dealing with gas lines or live in an area with strict regulations.

Can You Use A Regular Water Heater In A Tiny Home

You can use a regular water heater in a tiny home, but it’s not going to be ideal. Traditional water heaters take up a ton of space and energy, and tiny homes just don’t have the room. On the other hand, RV, tiny house, and tankless water heater models are designed to be compact and use space more efficiently.

Should You Get An Electric, Propane, Or Solar Tiny Home Water Heater?

Standard propane water heaters perform more efficiently than electric heaters and are more environmentally friendly. They also get hot pretty much immediately and cost less to run. That isn’t to say that that electric and solar water heaters don’t have their place.

Solar water heaters are great in terms of efficiency and sustainability, but because they’re weather-dependent, they often require a backup. Similarly, electric water heaters are easy to install, safer than propane tanks, and have lower upfront costs, even though you’ll end up paying more over time.

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Your Turn!

• In your experience, which water heater has performed the best?
• Would you rather have a tankless tiny house water heater or a tanked one?

By Ryan Mitchell on May 21, 2025   /   Tiny House   /   6 Comments

Tags: Construction, Electrical, Tiny Home