Top 3 Off-Grid Water Heater Systems
There are several options available for off-grid water heaters. The most convenient and least complicated of which is the gas-powered on-demand system.
I have spent countless hours researching hot water options for my off-grid cabin. Hopefully, I can save you some time by sharing what I have learned so you can enjoy the convenience of hot water at your cabin too.
The two things you need for off-grid your hot water system are energy to generate heat, and a source of water. In this article, we will only discuss off-grid water heaters and we will cover the water source part in another article.
Tankless on-demand hot water heaters are highly efficient appliances suitable for off-grid cottages. But, there are several off-grid specific pitfalls to watch out for.
Top 3 options for off-grid water heating
While there are lots of great DIY off-grid hot water systems out there, we want to be sure our cabin is safe for our family members and it is around for future generations to enjoy so we are focusing only on the options that will pass a home insurance inspection.
1. Propane Tankless Water Heater
Tankless on-demand water heaters give you an endless supply of hot water. It heats the water you are using immediately so you are not wasting any energy heating unused hot water. You can choose from electric and propane-fueled tankless water heaters. We found that the propane tankless water heater made the most sense for our needs.
My cabin is a water access-only place and I need to bring my propane tanks in by boat. But it is still the most convenient and reliable hot water system for my needs. 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 cooktop, and even refrigerators.
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. Here in Canada, in the summer months, it takes an average of 650 BTUs to heat one gallon of water through a tankless propane water heater.
How to calculate how much propane you need to heat water
In general, an average person uses 12 gallons of hot water per day. So then 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 is 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.
This 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 hot water needs.
Indoor VS outdoor propane tankless water heater
When you start to research propane tankless water heaters you will learn that there are indoor models and outdoor models.
The main difference between the two is that outdoor models do not have to be vented. If you purchase an indoor model, you will need to vent the water heater properly, which means you will need to vent the water heater to the outside through the wall.
Another thing you will have to plan for if you choose an indoor water heater is the issue of condensation. Indoor water heaters not only need to be vented, but condensation has to drain out as well.
If you choose an outdoor water heater, it will need 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.
If you are building a new place and live in a cold climate, it makes sense to choose an indoor tankless water heater that you can build into the structure.
If you are adding a tankless water heater to an existing building and live in a milder climate, then an outdoor water heater might be the preferred choice.
2. Point-Of-Use Mini Tank Electric Water Heater
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.
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. I have met people who use this system powered by solar or wind-charged batteries and backed up with a generator system.
3. Solar Collector Hot Water Heater
A solar collector circulates hot water through tubing that sits in the sun, and then sends the heated water into the water heater. Prebuilt solar collectors are easy to install and 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). The downside is that you need to live in an area that gets enough sun (which I do not) to heat the water year-round.
Things to Consider When Buying an Off-Grid Water Heater
If you have done any research at all into buying a water heater for an off-grid place you are probably aware of the fact that tankless water heaters are the most efficient on the market, and can produce an endless amount of hot water. Efficiency is a major selling point, as it saves on cost and trips to town for a propane refill.
Here are three things you need to think about when installing a tankless water heater off the grid, which most people won’t consider.
1. Ability to Limit Energy Usage
Some on-demand hot water heaters are energy hogs. Especially exterior units that use electricity to prevent their water from freezing. Try to set up your on-demand water heater so that it can run off something other than the main house power source to save you from the problem of your water heater using up all of your power.
2. Usability with Low Pressure (Low Head) Water Systems
Not all on-demand hot water heaters work well with low-pressure water. This can be a problem with high-efficiency DC well pumps, low head gravity fed water systems, or spring-fed off-grid water systems. Make sure you find a water heater that can work with low pressure as well as high-pressure water systems so that you will have hot water in a back up situation
3. Runs from propane
Propane is ideal for heating water off-grid because it is transportable and widely available.
Off-grid water heater FAQ
Can you use a traditional hot water tank off-grid?
It’s not impossible, but it doesn’t make sense because of the high amount of energy needed to run a traditional hot water tank system. You would need a large propane source or a crazy number of solar panels just to heat water.
Can you use an electric tankless hot water heater off-grid?
Electric tankless water heaters are tempting because they seem less expensive than propane ones. This, of course, will depend on how many gallons per minute (GPM) you are comparing. Installation of an electric tankless water heater is much cheaper because it doesn’t require a complex ventilation system. Saves Space Tankless water heaters save a lot of space because they are mounted on the wall up off the ground. Unlimited Hot Water As the name suggests, with an electric tankless water heater, your hot water supply is on demand. 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. But they do have super powerful heating elements that flash heat the water when you turn on the hot water tap. This 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 set up. It wouldn’t really make any sense to try and run one of these using an off-grid energy source.
An Off-Grid Hot Water Heater Makes Life More Comfortable
There are several ways to attain hot water while living off-grid that are functional and practical. Modern propane tankless hot water heaters give you the option to have on-demand hot water without having to harvest timber or boil water. You will have to spend some money for the convenience, but I think it’s worth it!
If you would like to learn more about setting up your off-grid cabin or cottage, check out our other off-grid articles.