Last Updated on June 8, 2021 by Regina Cal

5 Legit Methods For Off Grid Hot Water Heater Systems

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When building an off grid lifestyle, there are comforts of modern day living that we just do not want to give up. On-demand hot water is a modern comfort that we have grown accustomed to; we feel it is a necessity for life as we know it. Not too long ago in history, hot water was a nicety that was only used for cooking and for the occasional bath. If you wanted a hot bath, you would have to boil water and pour it into a wash basin. I could only imagine how many kids were doused in a tub of cold water!

This is the way our great-grandparents washed up!

My appreciation for hot water began when I moved into a camper full-time. We were on a 6-gallon hot water heater which allowed for maybe 5 minutes of hot water. I had grown accustomed to 30 minute luxurious steamy showers where I could daydream and shave my legs at my leisure.

Now, I have to plan accordingly and shut off my hot water intermittently just to have enough to get through a shower.

This really got me thinking about how we can manage to have continuous hot water in an off grid scenario.

I have spent hours of research building this very article to provide you with the best ways you can build an off grid water heater system so you can enjoy modern day living without being connected to municipal water and heating source.

Let’s get into the good stuff!

Off Grid Water Heater Basics

The essence of being off grid is to be independent of municipal sources. Being free from monthly utility bills and providing your home with your own energy is the foundation of living the off grid lifestyle.

There are two commodities that you will need for your off grid water heater: energy for heat and water. When it comes to energy, there are three main sources you can harness to heat your water:

1. Energy from the sun

2. Natural Gasses

3. Burning wood

Using wood to heat your water is by far maximum off grid. Your system requires no moving parts (which means no breaking down) and you can harvest your fuel from your rural surroundings. This is also the most labor-intensive method as you will need to start your fire anytime you want hot water and you will need to collect your wood. You will have to stoke the fire consistently. It is the most primitive way to attain hot water. 

Another option is to use the power of the sun with a solar water heater. You can easily create a DIY solar water heater or purchase anywhere from a cheap portable solar water heater to a high tech expensive roof mounting solar water heater. 

Propane is a happy medium for an energy source if you are living off grid and are close enough to a town to purchase propane or have it delivered to you. This winter, we plan to have a 250 gallon propane tank installed on our property and pay for delivery. In our off grid camper, we use propane energy for our furnace, our cooking, and for water heating, at least for now. 

Technically, using propane is not quite off grid since you are relying on a municipal source of energy. That being said, since you are not hooked into the system and do not have to pay a monthly bill for energy, I still consider it off grid. Propane tankless water heaters are a popular choice for rural dwellers and off grid homesteaders.

5 Practical Methods For Off Grid Water Heating

Now that we covered the basic ways to heat water, let's go over some practical installations of water heating that can be used for the off-grid lifestyle. 

1. Propane Tankless Water Heater

Even though using propane is not necessarily the most off-grid friendly energy source, it makes sense in a lot of situations. Virtually every small town and almost all gas stations have propane services. There are private propane companies that will fill up your tanks at your property. You can use propane for other appliances too, like your furnace, your cook top and even refrigerators. 

If you are trying to build a fully autonomous off-grid lifestyle, then propane would not be your best choice. 

How much propane does a propane tankless water heater use?

This entirely depends on your usage. The water heater heats the water to 120 degrees; depending on your region depends on how many BTUs it will take to get to that temperature.

Let's use the Northern USA region as an example. It takes an average of 650 BTUs to heat one gallon of water through a tankless propane water heater.

The average person uses 12 gallons of hot water per day – I think this can be shaved way back with conscientious water usage.

Multiply your BTUs by gallons:

650 BTUs X 12 gallons = 7,800 BTUs per person per day


Now, we figure in how many BTUs are in one gallon of propane - it is 91,502 BTUs. Divide your BTUs per gallon of propane by daily personal usage:

91,502 / 7,800 = 11 days of usage per person

With these calculations, 1 gallon of propane provides 11 days of hot water to the average person. That is pretty darn good!

Now, this figure can vary greatly depending on what region you live in, seasonal water usage variations, how many people you have in your household, how many appliances are using the hot water, and how much hot water each person really uses. So take the time and calculate your hot water usage to figure out if a propane tankless water heater is right for your off-grid lifestyle. 

Indoor VS outdoor propane tankless water heater

As you start to shop around for these water heaters, you will notice that there are indoor models and outdoor models. The main difference between the two is that outdoor models do not have to be vented since they are outdoors. If you purchase an indoors model, you will need to vent the water heater properly, which means boring holes through walls.

Another factor when choosing between an indoor or outdoor water heater is condensation. Indoor water heaters not only need to be vented, but condensation has to drain out as well. However, if you choose the outdoor version, it will require more propane to heat the water in colder climates and through winter. If it is extremely cold out, it could freeze the unit and cause irreparable damage. Not good!

If you are building a new home and live in a cold climate, it makes sense to choose an indoor tankless water heater which you can build into the structure. If you are adding a tankless water heater to an existing build and live in a milder climate, than an outdoor heater is the preferred choice.

Indoor Propane Tankless Water Heater Product Recommendation

The Rinnai indoor tankless water heater provides a 6.5 GPM flow rate, which accommodates a small to medium size cabin. It operates with high effeciency and provides on-demand hot water instantly. This is a great choice for an indoor water heater that runs off propane. 

rinnai tankless hot water heater

Outdoor Propane Tankless Water Heater Product Recommendation

The Camplux Pro outdoor water heater is a compact heater that produces 1.58 GPM, which is good for camping and a small cabin. Although they do not provide as much on-demand hot water as the indoors version, the price range is much more affordable and you don't have to worry about venting. 

camplux outdoor propane water heater

2. Point-Of-Use Mini Tank Electric Water Heater

Although standard size electric tankless water heaters are out of the question, I found these mini tank electric water heaters that are installed at the point-of-use. They do not take nearly the power that the full size water heaters do. 

These water heaters range from holding 2.5 to 7 gallons of hot water and use 1400 watts. Not a bad cost of energy compared to other water heaters.

The downside is that you will need to install one under each fixture you plan to use hot water. This could add up to a heavy electrical load if you are not careful about when you are running the hot water.

I do think with some careful planning and for small off grid installations, these could work really well.

Bosch Electric Mini-Tank Water Heater

This is a 4 gallon point-of-use water heater that comes in under $200. This uses 1440 watts which is easily manageable. You use less water too as your hot water is delivered instantly to the source. This is perfect for RV boondocking and small cabin installations. 

bosch mini tank water heater


3. Solar Collector Hot Water Heater

Now you may have not seen one of these before, but they are getting more popular as the price of heating costs increases. 

A solar collector circulates hot water through tubing that sits in the sun, and then sends the heated water into the water heater. 

These prebuilt solar collectors are quite expensive, but are easy to install and to integrate into your hot water system. The nice thing about solar collectors is that there are no moving parts that could break down, so the unit is virtually maintenance free. You can also get a clean energy rebate for your purchase (check with your local jurisdiction for energy rebates).

solar collector hot water heater


4. DIY Solar Hot Water Heater

To get into the DIY spirit, you can build a solar hot water heater pretty easily and for practically free!

The method is quite simple: 

1. Find a used, broken traditional water heater. You can find one for free at landfills, building supply stores, and local appliance shops. They can't even give these things away!

2. Strip away all the bits and pieces until you are left with a bare tank.

3. Paint that tank completely black. 

4. Connect a hose into the tank and fill it with water. 

5. Let that baby bake in the sun, and you will have piping hot water!

DIY solar hot water heater


You can magnify the effects of the sun by building a box around the tank. Paint the inside of the box black. The top panel of the box needs to be glass to allow the sunlight to come through. You can find a cheap used sliding glass door or old window. 

This can be a great way to heat up an off-grid hot tub, pool, and be used for your indoor hot water needs as well. 

Listen to our podcast for more details on how to build and install this DIY hot water heater:

5. DIY Wood Burning Hot Water Heater

If you are wanting an autonomous water heating system that does not rely on technology, moving parts, and municipal fuel, then a wood burning water heater is the only way to go.

This is an excellent choice for off grid cabins that are very remote and has a lot of timber available for fuel. Be prepared to do some wood cutting if you go with this type of water heating system!

From what I have found, there are no pre-made wood burning water heaters for sale. Alas, they are very simple to make with a bit of engineering and elbow grease. That’s how we roll when we are off grid – we make shit!

You will need:

Hot water heating coil -or-

copper tubing

Copper tubing Product Link

Wood burning stove

Range boiler tank

Wow guys! I finally found a product you cannot find on Amazon! The stone lined range boiler tank! This is an older tank that holds hot water which was used in the old times. The only reliable source I found these tanks at is the manufacturer: Vaughn's. They're not cheap but work well for holding hot water heated from a wood burning stove. They are built to convect so the water stays hot. You might be able to find used and antique models on Facebook Marketplace or Craigslist. 

This is about as easy as it gets. Step one: mount the water heating coil or copper tubing to the firebox of the wood stove. Step two: attach the range boiler heater to the hot water coils. Step three: Plumb in cold water to the range boiler tank.

diagram for a wood burning hot water heater

Here is a real life example of the wood burning hot water heater using the range boiler: 

stovepipe wood burning hot water heater

You can also make a rocket stove water heater by simply placing a coil into the stove.

Off Grid Hot Water Heater Q&A

Here are some answers to some frequently asked questions about off grid hot water systems. 

Can you use a traditional hot water tank off grid?

The short answer is yes, but the long answer is that I do not recommend it, and I will tell you why. 

Traditional tank water heaters either use natural gas or electricity for heating. Natural gas water heaters are off the table since we don't want to rely on being connected to the gas company for energy. Electric tank water heaters are an off grid option, but we need to calculate how much energy these units need to heat the water and if your solar panel setup will cover those needs.

Traditional Tank Water Heater Solar Power Calculation

According to energyusecalculator.com, a traditional tank water heater uses 4,000 watts per day and runs for about 3 hours per day. 

A 250-watt solar panel will provide 250 watts per hour when the sun is providing full direct sunlight for about 4 hours per day, equaling about 1000 watts per day output. 

We divide our water heater watts per day usage by how many watts the solar panel provides:

4,000 / 1,000 = 4 250-watt solar panels

That is a lot of solar panels just to power the water heater! This does not account for energy loss from converting the power into A/C, nor does it account for cloudy days either. As you can see, a traditional hot water tank is just not all that feasible for the off grid lifestyle. 

Can you use an electric tankless hot water heater off grid?

The short answer is NO. These types of hot water heaters are absolute power hogs! It wouldn't really make any sense to try and run one of these off an off-grid energy source whatsoever. 

I was looking at the manual for the Tempra Series water heaters made by Stiebel Eltron and the minimum watts required for their smallest water heater is 9,000 watts. Their largest one uses 36,000 watts!

Now, electric tankless water heaters do take less energy to run than their traditional counterparts because they do not have to run all the time to keep water stored in the tank hot. Rather, they have super powerful heating elements that essentially flash heat the water when you turn on the hot water tap.

This, in turn, creates a heavy load on your electrical system, requiring a substantial increase in amps and breakers. Most normal households on the electric grid require an upgrade to run these water heaters, let alone an alternative power setup.

Let us entertain the thought of using one of these bad boys on an off-grid power setup. If I had a mid-size electric tankless water heater requiring 20 kilowatts, I would need 16 deep cycle marine batteries (at 12v 105amp) just to trigger the heating elements. I could only imagine how taxing that large of a draw would be on a battery backup system!

I recommend steering clear from these hot water heaters for an off-grid installation. 

Conclusion

There are several ways to attain hot water while living off-grid that are functional and practical. Modern techniques give you the option to have on-demand hot water without having to harvest timber or boil water. You will have to spend some $ for the convenience, but I think its worth it! We use propane for our small RV hot water heater, and it works just fine. 


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About the author

I created Maximum Off Grid to help others learn to become more self sufficient and practice sustainable living techniques. I love gardening, prospecting, being outdoors, writing and content creating.

Regina Cal

  • Hello Regina! Very nice blog. I also use an off-grid water heater at my home and it’s an ideal option for hot water. Thank you for letting us know about some other water heating solutions. I will surely try these too. Keep sharing, keep blogging!

  • Hi! I ben thinking about skiping the boilertank. And go with stove+coppercoil to a radiator instead. Will there be any problems this way?

    • Using a radiator is a creative idea, it pretty much works in the same way as a boilertank. I think it would be ok, however I am not a radiator expert.

      Give it a try and let me know how it goes!

  • Thanks for this blog. I’m looking at building a cabin in the Pacific NW that is totally off grid. You’ve given me a lot of information for me to be able to make better decisions with the planning.

    • Aww thanks! I am so glad I could help you out with all this information I have created. Good luck with your off grid journey!

  • Hello Regina! Very helpful blog! I am a student and for my project we need to come up with a sustainable off the grid house. Which of the water heaters do you recommend. Do you have any tips that might help us?

    • Hi there and thank you! I would recommend to go with the woodstove/coil method. This way you can heat your home, make hot water, and you can also cook on a wood burning stove. Three off grid systems in one!

  • Hello Regina:

    Thank you for the information, it’s straight forward and educational….well done 🙂
    I remember seeing the wood burning hot water tank set up as a kid at my grandparents farm in Quebec. I have recently bought a property on a lake in northern Ontario and I’m starting to look at my options for heating/lighting. I would love to somehow design/build a system that takes all these options and works together I.e solar panels with batteries for electricity, propane, solar hot water and wood burning heating for personal hot water AND in-floor heating of garage and house. I know that’s a lot of things I’ve thrown at you but would appreciate your feedback if you have the time.

    Regards

    Pierre

    • Hi there and thank you for the compliments! Going off grid is a journey, it takes a whole lot of time and system building and things don’t ever seem to work quite right, lol. I suggest starting with your biggest priorities, electricity and heating. Ontario is very chilly! So you will want some redundancies for your heating. Have propane, wood burning, and electricity for heat source. Do you get much sun up there? How about wind? Wind power is actually great. I would look into that too. I have a podcast episode that covers a DIY solar water heater: https://theoffgridoutpost.com/podcast/going-off-grid/podcast-do-it-yourself-solar-hot-water-heater-for-pennies/. Keep me updated on your journey!

  • Your article is fabulous in everyway, thank you. I’m thinking about building an off grid home, So the details you provided in your article are invaluable to me. Thanks again.

  • Great job. Information given concise manor. The facts in a way anyone can understand. Learned several things for this article. Thanks

  • Hi! My brother made a coil to go in his wood stove and his insurance company came around for verification purpose and they condemmed the hook up. Although it was realy well made and that he used it for years before.

    • That’s terrible! It really makes me mad that these tyrannical controlled corporations dictate what we can and cannot do with our own property!!! Makes me sick!

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