I would like to be able to measure how much water do I use from well in the garden, based on electricity that the pump is using. I have Aeotec Heavy Duty switch that is reporting on every 2W change. However the length of pump cycle depends if I am also using water as it is running.
For instance, it takes 16l of water for pressure to drop and pump starts operating. If I am not using water during that time, pump takes ~40 seconds to fill the tank back, it turns off. Meaning - if my cycle is ~40 seconds, I know I have used 16 liters of water.
However if I use the water at the same time, it could very well be more (depending how much water I use). For instance, it could be ~2 minutes, then I used 35l of water (just as example). Eventually, I could just say if the cycle is more than XY minutes, just count 40l.
I know this is not super precise, but I already measured 16l when I am not using water at the same time, and I could use hose with maximum output to measure how much water do I consume and how long does the cycle take. If the cycle length is wide, I could just say anything between matches amount of water used between.
Is someone using it the same way? Any ideas how to achieve it?
If you pump 16L in 40 seconds then your water usage is just 0.4L for every second the pump is on. Some of the measurement may be delayed due to the required pressure drop but it will all add up over time.
No, pump always fills up the tank. So when pump kicks in, it means 16l from the tank “is gone”. And depending on how long the pump operates, it either fills those 16l back in ~40 seconds, or if it operates for instance 2 minutes, it fills back 30l (or so)
You cant “create water”, you have used the water from the tank. The pump refills the tank. Thus the on time of the pump records how much you have used. It may be delayed a bit because of the pressure drop required but it will eventually be recorded.
If it stays on longer because you are emptying the tank while refilling then that is recorded too, as a longer on time.
water_use = pump_on_time * 0.4L/s