water flow controller

[gkasprow]

Due to high temperatures in Poland I started rebuilding my air-conditioning system. It's design is quite non-standard since I use water to chill the air.
The recuperation installation was equipped with water-air heat exchanger. I have own water source which I use for watering my garden. But there are other users that also use the water (i.e. my neighbour) so the water flow is not deterministic. For AC operation, there must be continuous water flow to keep nice 20 degrees air temperature.
So I decided to build water flow controller that keeps minimum flow over the heat exchanger. Water is dumped to the micro-drip watering line. I don't want to keep it operating all the time because that would be too much for my garden. I.e. during night the air temperature drops below 19 degrees so there is no need to chill it. During the day temperature exceeds sometimes 38 degrees.
The idea is simple - install water flow meter with pulse output, motor-controlled valve, two temperature sensors and make a controller that takes care of it.
Moreover, I want to optimise the water flow to keep the well pump operation minimal to save energy.
So I purchased set of equipment, built simple controller and I'm going to have fun.

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And here is full installation

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Firmware is here

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And the control panel..