Solar Thermosiphoning Hot Tub Heater

Step 4: Wait for it to Warm Up

I'm still rebuilding. This green garden hose will be replaced by rigid 1-1/4-inch PVC tube plumbed into the plastic stock tank.

Now it's easy for me to see why the old design didn't create a thermosiphon pump. I'll update with results of the experiment.

Thanks for reading. Feel free to post suggestions.

Comments

[ferralll]

I am not sure if your design will work for just a thermo siphon. The coiled shape does not give a perfect thermocline for the water to flow through.

You would need to have a constant upward grading to obtain a natural flow, and that is not really possible with a looping system like that. But the idea is good!
I actually designed almost the exact same system. If you want to do it for a bit cheaper, try using irrigation tubing rather than a hose. The cost is a huge difference, although it is a bit less flexible and requires a bit more time and care to make.

That being said. You can buy some cheap little pumps that would work, and it is not hard to modify a submersion pump to act as an in-line pump.

[rrsounds]

Do you have at least one one-way valve somewhere in the system? I think that would help keep the water cycle flowing in one direction. Otherwise, the pressure from the heated coils will apply equally to both sections of the hose headed back to the hot tub. Give it only one-way to go and I think it will flow nicely, depending upon temp and height differential.

[jtmcdole]

What about having a closed system, with some type of exchanger in the tub?

[burntbob]

keep experimenting with it!!! might need to try different coiling patterns to see what works best but at least you are trying!! let us know how it works out... I wanted to try the same thing but havent had time to make a prototype so I really want to see what works out for you!!!