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Year-round Solar Water Temperature Sensor (imgur.com)

submitted 1 year ago by kaedon to c/diy

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A small solar power system to run a LoRa water temperature sensor year round. Here's some pretty graphs of the data:

https://www.kaedon.net/mitigomish/watertemp

This is a project that's been running for almost 2 years now. Everything is still working with very little down time! The solar power system is way overpowered for what it's doing, but I wanted to make sure it works through the dark winters.

The temperature sensor is at the bottom of a bucket in the ground, because the water level gets pretty low in the winter and I didn't want the ice to destroy the temperature sensor when it drifts.

Any thoughts or suggestions for improvements are welcome!

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[–] CadeJohnson 5 points 1 year ago (2 children)

I used to have a solar water heater for my swimming pool, and it had a wax-actuated valve (!) When the water in the panels was hot enough to melt the wax, a paddle could start turning, and water could flow in the panels. If the water cooled, the wax would congeal and the paddle would "freeze" - blocking water flow - the pool circulating pump had a pressure regulating valve and relief valve, so when the panels on the roof were not accepting water, the pump would bypass them and deliver water straight to the pool without heating. I thought it was quite clever (the wax and paddle assembly were inside a sealed device - I never actually saw how it functioned, only recall the vendor explanation). I have not seen a comparable invention in several internet searches over the years.

[–] cybermatrix 1 points 1 year ago (1 children)

Do you by any chance mean this type of valve? https://en.wikipedia.org/wiki/Wax_thermostatic_element I must agree, it is quite ingeniously thought of

[–] CadeJohnson 2 points 1 year ago

I am not sure if that is the same; the assembly on the solar panel was larger diameter than the rest of the piping system perhaps around the size of a two-inch PVC ball valve, where the rest of system was (if I recall right) about 1-inch or maybe 1.5? But I guess there could have been a component like this inside. I am familiar with these for automotive thermostats in cooling systems, but I never pictured that they might have meant this. Otoh, why not? It would do the job and maybe work for OP's project; especially if they are made for a range of different temperature conditions.