Rocket Stove Water Heater // PART II // Initial full setup // Thermosyphon Issues
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- Опубликовано: 10 сен 2024
- In my attempt to set up my Rocket Stove Water Heater I am having issues with getting the thermosyphon to start. I am obviously not an expert in this so am learning through trial and error. I am maybe being too ambitious with the length of pipe I am using.
Without much prior knowledge I am starting with what I would ideally like and working back to what turns out to be possible. Any constructive feedback on the technical side of thermosyphons would be greatly appreciated.
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FYI: the smaller the diameter of the pipe the greater the friction of the water moving through it. This knowledge can help in many applications
Cheers!
you'll need to fill the container above the level of the inlet to get thermosyphon going. Cold outlet at bottom of container to bottom of heater coil. It may struggle to push hot watet through all that pex, that's a lot of resistance. Good luck though. Interested to see how you get on. My thermosyphon was 22mm coper into a barrel next to burner.
Hi Neal. Thanks for the feedback. Yeah it took some experimenting but I finally got it working, tank much higher was key, as you say. Here's the video ruclips.net/video/X3n7POMqS_c/видео.html Cheers
This is not Thermosiphon. What ultimately powers Thermosiphon is gravity. As water warms, it becomes less dense and rises(away from gravity) in comparison to cooler water. It is an extremely low energy process. Horizontal runs only apply drag to the flow. Coils while easy to form have far more horizontal component than vertical so do not thermosiphon well if at all. The heat source and exchanger should be at the bottom, with it’s outlet at the top going only upwards to near the top of the reservoir. Any downward turn or droop will severely impede the flow. The bottom of the reservoir should connect down to the bottom of the heat exchanger. The reservoir needs to be filled so the top port is under water, as like any siphon air in the line will halt the process... because of the coil it will still boil as the flow will be too slow to move the water away fast enough to prevent it. With proper Thermosiphon flow it won’t boil until the reservoir is very warm.
Ideally you want the collector tubes to be vertical for best flow. The better the flow, the lower the water temp, so it will have a greater temp difference between water and fire so faster more efficient heat transfer(more hot water for less fuel). You can do something far more efficient using the same length of copper just separated into 3 or 4 pieces and coiled much more steeply. Right now you are probably coiled like a spring, visualize 4 tubes in parallel coiled more like steep corkscrews. You put the ends of the 4 tubes into a larger copper fitting squeezing and forming the ends as necessary for a good fit then either sweat them in place or use something like JB weld to bond them. If the flow is good and it has water in it, it should never get warmer than 212F. Then you can attach larger hoses to the larger collector fittings. If you keep hot water always flowing upward and cold water downward and avoid horizontal like the plague it will work well. I have built 2 diesel generators, and both coolant flow exclusively by Thermosiphon...
I really appreciate the detail in your explanation. Thanks for taking the time to explain.
Thanks for the tips, I'll be building one soon, hopefully it works great.
I bought 15m of copper pipe and was planning on doing a big coil like he did, now I'll probably cut it in 3 pieces and make a steeper coil. Thanks a lot for the time writing everything down rronmar!
@@ÁrvoresEmadeiras yep, the steeper the better. I was sketching together an idea using common copper fittings and straight pipe, to form a cage for the fire to set in, inside a box. If the sweated fittings are not inside the firebox, and the tubes always remain full of water this would work fine, if they were silver soldered together they could probably even survive in the firebox. With vertical tubes it will flow very well. Good luck on your project, put up a video when you get it running.
@@rronmarawesome, I'll put a video once I get it done, it will take a few months because I will do it in my new home that's not finished yet.
You can wrap the inside of the barrel with your tubing and still heat your water
As you say, it could still be used to heat water, but would be a lot more efficient
Am using the same concept except I'm using solar to run my fan for the forced air furnace
Sounds like a cool project.
Wrapping the pipe round the bio digester. That’s what I couldn’t yet imagine. How to emit the heat with a thin pipe.
That was my initial plan. Between the insulation and the barrel. I wont be doing that now with all the experimenting I have done I have decided it can't work without a pump to move the water through the pipes. Not sure exactly what I will end up doing yet though.
You need to pump the water. And as the water passes through the line it will get hotter. You are creating steam and the can not flow. The air from the steam is stopping it from flowing. You need a pump.
Thanks for the suggestions. The whole process was an interesting learning experience, was fun but at the end of the day it wasn't viable for what I wanted it for.
Why don't you turn that rocket stove into your furnace. Just run some piping through it at an upward angle put it in a metal barrel insulate the barrel draw the cold air from the bottom and run the hot air out the top separate the barrel into 2 half top and bottom. The heat will circulate the air no fan needed.
You know what I was genuinely thinking about something like this last night. Rather than heating water to heat the digester to use the hot air from the rocket stove.