Hot water. Most of us just take it for granted, but when it isn't there we realize what a luxury it is. And if you're seriously planning a tiny house, you'll need to decide on a tiny house hot water heater. In this post, I hope to help introduce you to all of the options you have when it comes to producing hot water for your tiny house. Which tiny house hot water heater option you choose will depend on your budget, whether you are on the grid or off the grid, and what your hot water needs are.
Just a quick reminder: In last week's post, we talked all about the challenges and options for getting running water in your tiny house. That post may serve as a good pre-requisite for this one since there's no way for you to have running hot water in your tiny house if you don't have running water at all!
Tiny House Hot Water Heater Options
Obviously, if you want to have hot water in your tiny house, you'll need some kind of hot water heater. Luckily there are a number of hot water heater options available for tiny houses because they are the same units found in RV's and in marine applications. Just beware: Some recreational hot water heaters are not designed to stand up to the rigors of everyday use!
The first major choice you'll make when it comes to hot water heating appliances is what fuel it will run on. And your choice in fuel really comes down to what you have access to.
Propane vs. Electric
Propane hot water heaters tend to be more powerful, more expensive to purchase, and require little electricity to run. For example, the unit that I use in my tiny house runs on propane and is made by PrecisionTemp. It uses almost no electricity, and since I was already running propane lines for my stove and heater, it was an easy decision to go with a propane hot water heater.
The PrecisionTemp NSP-550
I chose the NSP-550 because it vents through the floor of my tiny house, rather than through the wall like most other propane hot water heaters.Learn More
On the flip side, electric hot water heaters tend to be inexpensive to buy, but require more electricity to run. This will probably be a challenge for you if you plan to be off-grid and produce your electricity with solar panels.
If you are going to have constant access to electricity, electric hot water heaters are a much more affordable option. For example, Malissa and Chris Tack of the Tiny Tack House installed a 4-gallon Bosch electric hot water heater that currently costs less than $200 on Amazon.
However, since they rely on solar panels to generate their electricity, they have to be very careful about when and how they use hot water. As they explain in a helpful article about their solar setup, “By wiring our 4-gallon hot water into a switch, we leave it turned off when not in use. We also take military-style showers (water on long enough to get wet…back off…soap up…rinse off…done). This in conjunction with our low-flow shower head saves oodles of unnecessary power to heat water.”
As with many appliances, the up-front cost isn't the only thing you need to look at. While propane hot water heaters are expensive to purchase up front, they are less expensive to run over time because Propane is better at heating up water than electricity.
Tankless Hot Water Heaters (On-Demand hot water) vs. Traditional Hot Water Heaters
On-demand hot water heaters are a much different animal than their tank equipped counterparts. In an on-demand hot water heater, the water is heated as it flows through the appliance. Hence, on demand. However, this type of unit requires a lot of power in order to complete that task.
Electric hot water heaters often don't have enough power to create hot water on-demand. As one Amazon reviewer explains about the Rheem RTE 9 Electric Tankless Water Heater, “you can only expect a 30 deg F rise in water temp at 3 GPM”. This means that if your water comes in from the cold at 45 or 50 degrees, your water isn't going to be very hot.
In my opinion, the on-demand vs. tank question is really one about your lifestyle. With a hot water heater equipped with a tank, you have a finite amount of hot water for any given time. For example, a 4-gallon hot water heater with a low-flow .5 gallon per minute shower head will yield about 8 minutes of shower time. Then you have to wait for the unit to make more hot water. You never have to make that choice with an on-demand unit.
The Downside to Tankless
However, there is a dark side to tankless hot water heaters: they are susceptible to freezing. Since they usually use copper piping and heating elements inside, if your tankless hot water heater has the opportunity to freeze, it can easily rupture and be destroyed. Some of the higher end units come with built in freeze protection which will be essential if you live in a cold climate. Other inexpensive tankless propane units are only designed for outdoor use and have no way of keeping themselves from freezing.
Make sure you do your research before you buy any tankless hot water heater by reading the manufacturer's installation and use manuals to make sure it will work in your space.
Water heaters that have their own holding tanks are more dependable, but more energy intensive in the long run. While an on demand unit requires a lot of power to heat up your hot water as you use it, a unit with a tank will slowly heat up your water but then keep it hot, waiting for you to use it. When compared back to back, hot water heaters with tanks use more energy than their tankless counterparts.
So what's the downside to hot water heaters with tanks? Well, other than the increased energy use and finite supply of hot water, don't forget that water takes up space! Hot water heaters with tanks definitely take up much more space than on demand units, since they need a place to store all that hot water.
As you add more appliances to your tiny house, you lose storage space.
Alternative Tiny House Hot Water Heater Options
Solar Hot Water
This article would not be remiss to mention solar hot water! If you live in a part of the country that has enough sunlight, the sun is an excellent way to heat up water. Believe it or not, you can even have solar hot water in the winter. At their core, solar hot water systems use the power of the sun to heat a non-freezable liquid, and then some kind of heat exchanger to heat the water in a water tank.
According to Energy.gov, there are several kinds of solar collectors and heating systems. Make sure to consult with an expert or at least do your research before taking the plunge. Solar hot water systems are usually expensive to set up ($1-3,000), but then require almost no energy to run in the long term. So you recoup your initial investment over time, similar to solar panels.
No Running Hot Water
Finally, there's no rule that says your tiny house must have hot water. There are countless examples of tiny house dwellers that do not have running water in their tiny houses! That includes Dee Williams, Dan and Jess, and more.
Hot water for basic washing and cooking is heated over a hot plate or using an electric kettle. This option will significantly reduce your tiny house costs by eliminating the need for plumbing, a hot water heater, and potentially not having to run propane lines.
What's your plan?
I'd love to hear your comments below about how you're planning to have (or not have) hot water in your tiny house!
For a more in-depth look at tiny house plumbing, hot water, and more, make sure to check out Tiny House Decisions! This is my comprehensive resource that contains all my best thinking on this topic in one place.