Friday, 19 May 2017

Return of the Arduino Dehumidifier controller.

My very good friend Oto has a problem.

He's moved into a new house.

He's wanted some space for his lathes & mills etc, which this has.

 After a few weeks, his machines are showing signs of going rusty.... Why is this?

 It's humidity.. after installing a dehumidifier, things have improved dramatically, except his electricity bill...

 It's time for a slightly revised version of the first project I did on this website back in May 2014 (where does the time go??!?)

It's got a similar display, except it's in Czech, but it has an adjustable set point for humidity, and a mode switch to set between auto , whereby it switches on 5 degrees C before the dew point, or manual, where it switches on when the desired humidity set point is reached.

The mode switch is S2 on the diagram below, and S3 is a centre-biassed momentary toggle, which is used to alter the set point up or down.

The set point is stored in E2PROM, and is restored in the event of power failure.

The temperature and humidity is read from a DHT22 sensor, and the dew point calculated.

The dehumidifier is switched on with a suitable rated relay, via T1.

Here's the code:

... hope Google's translate has done a reasonable job!

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