Originally Posted by
lowdrive
The first thing you need to do is find the highest resolution sensors available. Use 4-20 ma custom calibrated to the lowest range, such as 30 degrees on a temp sensor. Kele will custom range them for you. You might need a second, cheaper, wider range sensor to run alongside to read values when they get out of your limited range of the high resolution sensor. Once you get solidly within the limited range sensor, use that value.
The high resolution will allow you to see tiny direction changes, and make tiny corrections before you even move out of your target range. When you use very high resolution sensors correctly, a + or - 5% Humidity target is like the Grand Canyon.
For instance, if your humidity starts to creep too low (such as two or three down ticks in a row without an up tiick), make a tiny increase in you humidifier output. You can even run that increase through a short duty cycle. A few seconds on, and turn it off again for a bit, in order to observe a change. If there is no change or the movement continues in the wrong direction, increase the output or the duty cycle time. When you can read the smallest change, you have time to make small corrections.
Will this system use chilled water for cooling?
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