Thermosiphon equals free hot water

In this blog post, we created a video which explains how we use thermosiphon to heat our domestic hot water through our wood cook stove. We have received requests to create a video post which walks through the process.  We hope you enjoy the video and our attempt at creating a Youtube presence.  Our channel on Youtube is Living a Sustainable Dream. We would appreciate your support by subscribing to our channel and liking our videos.  This will encourage us to keep making more videos in the future.

Thank you for your support, and may you have a very Happy New Year.

Mark & Krista

5 thoughts on “Thermosiphon equals free hot water

  1. I love your posts, and seeing you on the videos.. “Happy New Year”, to you and your family. Sending Love and Hug’s to you all.
    Aunt “Patty” Dawn and Bruce


  2. Hi Mark – well done post and U-tube. Although my wife and I life in the milder Pacific temperate rain forest climate than your Idaho, we do have a similar system thermo-siphon system hooked up to our Pacific Energy woodstove, in conjunction with seasonal hook-up to 30 gallon “batch solar hot water heater”. I you plumbed the system for future solar water so I’ll quite certain you’d be interested about our system.

    Our Solar batch Heater is a 31 year old “Solway” manufactured unit, now long out of business… it cost us $1200 in 1985. Generally these types of units are not promoted in cold climates, but they have certain advantages in terms of lower cost and simplicity. I can also attest that they are appropriate for cold climates, but read on for the caveat.

    I would describe our unit as thus – it’s a 30 gallon tank coated with a black low-emmissivity (sp) coating set behind double glazing and into an insulated parabolic shaped container that helps direct solar insolation towards the tank. See my post that includes with a few photos of this “Solway” unit.

    Although we drain down the solar tank during the months of late November to early March to avoid freeze-up damage, this simple system has no pumps or electricity required, and we only need to turn a few valves to re-activate it in early March (i.e. fill up the solar tank and pressurize that part of the system.)

    From my perspective, here are possible downsides of the system

    1) The solar tanks are located outside our home so their is some heat loss to the environment on cool nights. But we overcome this by having the solar tank act as a pre-heater during spring and fall. We still get our hot water directly from the main tank that you show behind the stove, but the ‘cold supply’ to that tank comes from the solar batch water heater located outside. Therefore, the cold supply isn’t actually cold, it’s either lukewarm or partly hot. Then, we continue to fire-up our wood stove for an hour or two each morning or a bit more on cloudy days, which also gives an extra boost to the solar

    2) In draining down the system for 3 or 4 winter months we loose the solar potential, but during these months we have plenty of hot water form the woodstove anyway. I learned the hard way about the importance of drain down. Back in the early 90’s I failed to drain down the tank early off one year and it burst the tank. The crack had to be welded.

    3) During the summer months we tend to use the most of our hot water on sunny days. Also, we try not to use a whole bunch of hot water first thing in the morning, allowing the batch heater to ‘re-charge” by noon.” With people who are not used to a few of these inconveniences I would not recommend the solar batch heater.

    For years I have meant to add a 2nd home-built 30 gallon solar tank to the system, to help with these problems. I’m close to retirement, so I imagine this project will be in a few more years..

    To conclude, here is an excellent link I recommend you look at that has a much more detailed overview of the solar batch heater that wrote-up as a member of the British Columbia Solar Energy Society a few years ago:
    I now don’t recommend the incandescent bulb idea mentioned in the article, but rather a complete drain down of the tanks, as I previously mentioned.

    Please, don’t hesitate to contact me for the complete free PDF construction plans, with suggestions on siting considerations and other pertinent details. You can use my email address that is in the above article. Over the years I have sent it out to a handful of people and I’d love to be able to send it to you as well. You might find it as an effective low cost solar hot water system to you evolving off-grid home and lifestyle.

    Thank you as always Mark, for sharing and spreading your good work. You have much to teach and offer, and as a teacher you explain things well. All the best to you and your family in 2017, and I look forward to future developments and posts. In solidarity and peace – Bruce Witzel, Vancouver island, BC

    Liked by 1 person

    • Thanks Bruce, the solar water heater is still a hope for the future. This is great information, and I will save it for our future project. Bruce, I think you could do a Youtube on your system too.


  3. Good video Mark! Interesting to see how the system works. Would be interesting to have temperature gauges at a couple places on the system to see the results as the water travels.

    Liked by 1 person

    • I could probably install temp gauges on the cold and hot side before and after it leaves the water coil. It would be a summer project in which I would have to drain and take the system a part, but a great project. Currently, we use a laser temp gauge and take readings on different sections of the pipe. It isn’t perfect, but accurate enough for now.


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