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Top 5 Ways to Heat Water in a Tiny House

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Guest Post by Ryan Mitchell of The Tiny Life

Heating water in a tiny house can be a tricky thing; by its very nature, heating water is often a resource intense endeavor and many solutions are often bulky. These two things are often at odds with those wanting to live in a tiny house because we don’t have a lot of space and we’d like to be as low impact on the environment as possible. While the choice can be a difficult one to make, I think we all can agree, a nice hot shower is something we all enjoy.

So here are my top 5 ways to heat water in a tiny house.

1. RV-500 Tankless Water Heater by Precision Temp

This little tankless water heater is actually designed for motor homes, but it works quite well in a little home. For those of you who aren’t familiar with tankless water heaters, instead of a tank that keeps the water hot 24/7, it only heats as you need it. The upshot of this solution is that it is often uses a lot less energy and you can have endless hot water if you need it. The added benefit of this being an RV unit is that they make the venting really easy, they are quite small, and a standard propane tank can last you about a month and a half.  The downside is the price tag, at $1,000, it’s a hard pill to swallow, but owners sing praises of this unit.

RV-500 Tankless Water Heater

Image from http://www.precisiontemp.com

2. 10 Gallon RV Water Heaters

For those who aren’t quite ready to make the jump for the pricy RV-500, the next best thing might be a standard RV water heater.  They cost around $300 and will give you about 8 minutes of hot water, then a few more a lukewarm minutes. Like the first option, venting here is a real breeze because you drop this in so the access door from the outside allows the fumes to vent safely. This option is also pretty small at 16 x 16 x 19 inches.

Tank RV Water Heater

Image from http://www.americanrvcompany.com

3. Solar Hot Water Heater

For many this option is often a pretty decent choice, but may still require additional heating in the winter. I have only seen one tiny home with a professionally manufactured solar hot water heater on it and it looked a little bulky. So I think for this option, having the collector on the top of a nearby shed or free standing might be the way to go here. This option can run you a few thousand.

Solar Hot Water Heater

Image from www.easy-green-living.org/

4. DIY Solar Hot Water Heater

In the summer, outdoor showers are pretty amazing things after spending a long day outside. The beauty of a do it yourself solar hot water heater is its simplicity.  Many people just use a black garden hose that is flattened in a coil. These can be put together for about $50 and are a great option for the summer months or if you live in a very warm climate.

DIY Solar Hot Water Heater

Image from http://www.treehugger.com

5. Compost Powered Hot Water Heater

This is a pretty interesting trick that I have wanted to try for a while and might just be the ultimate solution: it’s cheap, doesn’t take much room inside your house, and very low impact. For those of you who have ever composted, you know if you make your pile the right way, the compost process makes a lot of heat. In fact, the ideal temperature is 160 degrees! We heat the water by using a small solar powered water pump to push water through a large coil of tubing that you have embedded in the middle of the compost pile. It’s as simple as cold water in, hot water out and into your house. Check out the video below on this technique.

Compost Hot Water Heater

Image from http://permaculturenews.org/2010/01/11/free-hot-water-from-compost-wheelie-bin/

Video on Composting Hot Water Heater

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Alex is a contributor and editor for TinyHouseTalk.com and the always free Tiny House Newsletter. He has a passion for exploring and sharing tiny homes (from yurts and RVs to tiny cabins and cottages) and inspiring simple living stories. We invite you to send in your story and tiny home photos too so we can re-share and inspire others towards a simple life too. Thank you!
{ 31 comments… add one }
  • Joel
    October 5, 2012, 9:15 am

    Perfect timing for this article, I’ve been thinking about this a lot recently and I wanted to add wood stove water heaters to your list. They can be as simple as a bucket of water left on the stove to more complex built in models. Combined with a small batch solar heater for warmer months this can provide hot water all year for free.
    Solar options are tricky in colder climates during the winter, usually this means anti-freeze in the panels that circulates through the system making them less practical.

    • October 5, 2012, 9:23 am

      Thanks Joel glad you thought of that!

    • Alynxia
      October 6, 2012, 11:41 am

      Yep, that’s the route we plan on going with in our plumbing-free tiny house. Solar bag showers & water heated on the woodstove. Although that composter bin heater is a neat idea. I wonder how one could set it up to work with a gravity fed water barrel system? One direct barrel for cold and one connected to the compost bin hose with an overflow to another barrel perhaps?

    • Patricia
      October 6, 2012, 2:27 pm

      Hmm, good idea but as I have noticed when trying to dry clothes, therei s a period of time in the spring and autumn when it will be not cool enough to have the stove going but not warm/sunny enough to heat the water by solar. Depending where you live of course. So I like the compost idea but may have to devise a way to mix it with cold water before it gets to the shower head.
      I would love to see if anyone has come up with a solution to the too hot for tender skin problem.

      • Heather
        September 19, 2015, 1:36 am

        Hi Patricia,
        My husband loves composting and one place where we parked our Tiny home, we had access to water but not hot water. So my husband was excited to heat our water with the compost pile. It worked great! It def became pretty hot so thankfully we had a mixer valve…outside one hose wrapped around a rain barrel and then covered in the compost. The cold line was just free running so it stayed cold of course. We were able to control the temp with the two lines and the mixer valve. But just remember to keep working the pile properly or no hot showers ?. The composting system will still work in the cold months as long as one tends to it correctly. Alex, currently we are in a spot in Loveland CO that will require us to provide our own hot water supply all together. We can’t hook up to the big house during the winter for fear that the outside line will freeze the pipes and cause flooding to the big house. Our house is only a 110V and therefore some of the “optimal shower” experience providing products are out. So our plan is to have at least 2-3 rain barrels filled, the hose/water line running with each barrel, each being covered by compost piles, then as an added barrier from the cold, we would set up a green house(durable in winter) around the piles. The lines from the piles to the house that were exposed to the elements would be protected in a winterized barrier. We also want to set up a copper coil system around the pipe from our mini wood stove to heat up (and then be stored) water which could be used for the same purposes. The copper coiling is new to us…so it will be an adventure!

      • Ladd
        February 17, 2017, 8:14 am

        Be easy to run in a cold water supply as well and mix just like standard shower in big houses

    • jack
      May 18, 2018, 10:33 pm

      Solar powered water pump
      submersible type
      Solar water pumps are often used in remote areas where the cost of running traditional AC powered water pumping is cost prohibitive or you just want to provide water to an off-grid home. Solar water pumping systems are also used to pump water for livestock and crop irrigation in remote locations.

      we supply Solar DC pump 80W~3000W, warranty 3 years, working life more than 10 years.

  • dew
    October 5, 2012, 2:33 pm

    Yes, yes

  • Lindy
    October 6, 2012, 12:20 pm

    I lived in Scotland for many years and one of the best things I ever saw there was an electric shower. I lived in a very tiny flat and did not have room for a water heater. The electric showers are connected to the mains, and the only water hose you have to hook up to it is the cold water. The shower is a small box that heats the water up as you are using it….and the water stays the same temp. So you can set it and just leave it unless you want to change the water temp. I do wish they had these in the states, because not only do they save lots of money on electric bills, but then you dont have to sacrifice space to a big water heater….And I love the compost pile idea!!

  • LaMar
    October 6, 2012, 12:25 pm

    You left out the most common On Demand water heaters that do not cost that much ($200-$400). They come in ventless or vented and have no standing pilot so they use very little fuel. Perfect for a cabin or HOW.

  • Pat
    October 6, 2012, 12:49 pm

    Homr Depot sells a 2 gallon hot water heater for $250. It plugs into regular 120 volts and is quick to install.it is as big as a 5 gallon pail and gives you a 3 minute shower with a quick recovery time.

  • jerryd
    October 6, 2012, 12:55 pm

    Lamar can you give some examples of those less expensive units?

    I really like the compost heaters and they can be increased in size to heat a home all winter.

    Another method is the 2gal well insulated plastic covered ones at home depot/Lowes for under $140 and couple them to high pressure but very low volume showerheads so you don’t run out of hot water. That is what I’m putting in my new 144sq’ cabin.

    They also have a switch and thermostat that if mounted on thev wall is easy to turn on only when needed saving much power.

    As I’ll have so much, way too much, DC power I’d like to find one that works on it if anyone knows of one for my trimaran build. Otherwise I’ll have to make my own.

    I’ll like heat my tri with 12vdc too. I have a couple 12v, 300wt car heaters I’m going to try.

    • LaMar
      October 6, 2012, 3:19 pm
      • jerryd
        October 6, 2012, 8:23 pm

        Thanks Lamar, that was rather interesting. I clicked on the Ecotemp link and saw the rest of their gas line and found a cool camping version for only $119 which looks interesting for my boat.

        ———–It was my first visit to Amazon. It’s so disorganized I couldn’t find amost anything else I wanted like PV panels, just some overpriced inferior units when I put in solar panels and other keywords and tried to find battery monitoring systems for my 72vdc nom EV pack but only found RC units. I’ll try again later.Luckily there are other sites that have them like sunelec.com for $1/wt PV and EVParts, etc for the others.

      • October 7, 2012, 11:22 am

        Thanks LaMar!

      • October 8, 2012, 9:18 am

        We use the Ecotemp $119.00 version. It works great – we just have to be considerate to each other when one of us is in the shower 🙂

        Great post, Ryan

        • October 8, 2012, 9:19 am

          Although I should add, we will be doing the ‘coil version’ on our roof next spring.

  • Glema
    October 6, 2012, 1:20 pm

    I appreciate your hard work and sharing gentlemen. It allows me to make informed decisions about which I will want and the time it would take for me to save for my dream. Thank each of you for sharing and Alex Thank you for your collaborative works. I am always reading and learning though I seldom comment never fear you are all prayed for. 🙂

    • jerryd
      October 6, 2012, 2:07 pm

      Hi Glema and All,

      Let’s not forget the great ladies that do a great job contributing here in articles and so many ways, not just gentlemen. It’s one reason I like this blog.

      Please don’t fear as we need different thinking on how to improve, use, tiny homes. And one learns best when one asks questions on topic of small home living.

    • October 7, 2012, 11:23 am

      Thanks Glema!

  • Glema
    October 6, 2012, 5:01 pm

    🙂 I pray for the ladies if I read. Or not hehehe

    • jerryd
      October 6, 2012, 8:27 pm


  • pam
    October 9, 2012, 7:56 am

    One caveat with the RV 10 gal heaters – if you live in a cold climate like I do, be sure that the pilot doesn’t have to be lite with a match, that’s it’s an electric ignition pilot…since these units sit directly in an outside wall..in windy weather the pilot can blow out (trust me I’ve been there in January icy weather trying to re-light my hot heater pilot), you don’t want to go there…

  • bobhenry
    June 3, 2013, 1:16 pm

    Water pumps . pump water. This water is routed via a tee fitting to the cold water circuit and delivered via piping to the cold water fixtures. The hot water is cold water that has been diverted via the tee fitting to the hot water circuit and is then heated via wood heat, electrical heating coil ,solar, or LP/natural gas. This heated water is delivered to a seperate hot water circuit so balancing the heat of your shower is as simple as balancing via the 2 valves to a single spray head. Scaldgard technology in the shower is nice as it senses the water temp and adjusts the temperature for you to a preset temperature by blending more cold water by the reaction of a bimetal coil that does the adjusting automatically. DO NOT simply throw a coil of black tubing or black hose on a roof and try and shower from it without the safeguards of being able to balance the hot and cold. It can reach temps well above 190 degrees. Don’t ask me how I know DUH !

  • tim
    June 3, 2013, 2:54 pm

    i spied a really great offgrid solution while traveling around south georgia. someone had erected 4 each 55 gallon black pvc drums on an elevated steel platform. the water was pumped in as needed to fill and the sun heated the water for bathing. a simple gravity feed at the bottom via a garden hose to the camper.

  • June 5, 2015, 1:41 pm

    We live in Alaska, where it reaches subzero temperatures. We chose a Laser 30 Toyostove. Works super well, ours runs on Diesel, but has the option of kerosene. in -30F there is no problems here 😀

  • Tony Savage
    June 29, 2015, 2:32 pm

    I love all these great DYI ideas to create hot water. There are some newer tankless water heaters just hitting the market that are smaller and more affordable these days. Perfect for a tiny house!

  • jane
    October 25, 2015, 9:16 pm

    I’ve seen too many Ecotemp tankless heaters fail, so I got a Rinnai. It’s much pricier, around $650, but I just didn’t want to risk the chance of fire. There’s a couple who live in a school bus that had one that blew, and they were lucky that it was mounted on the outside and only blackened the metal. I have cedar siding. It would have caught, I’m sure.
    I love the instant, unlimited hot water. I have a large tub, and I take one long bath per week, and showers in between. I have it hooked up to a hose outdoors, so I can shower outside in clement weather. It’s been perfect!

  • jane
    October 25, 2015, 9:53 pm

    http://minimotives.com/2014/07/20/flood/ – This is the link to the Ecotemp flood at Macy Miller’s house

    http://www.justrightbus.com/2014/06/EccotempReview.html – This is the one for the Just Right Bus issue that I just mentioned above. Scary!

    • JC
      December 2, 2015, 5:43 pm

      I gotta wonder why it’s Eccotemp’s fault when retrofitted units used outside of their intended use fail?

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