dehumid-case

thingiverse

This project is a retrofit designed to overcome issues with a dehumidifier's coils freezing up. Although it's unlikely that anyone else will replicate this build, the case design has been crafted in a way that can be easily modified for various other projects. Most features within the case are made selectable via flags at the front of the SCAD program, allowing users to delete or add components as needed. The mounting ears, display mounts and bezel, relay mount, and case tabs can all be removed with ease. Due to the complexity of printing this box, it is highly recommended that users print one piece at a time. During my own printing process, I encountered an issue where the USB subsystem went down halfway through, causing frustration. To resolve this issue, I transferred both prints onto the SD card and printed from there instead. The operation of the box itself is straightforward. It features a normally closed relay contact in series with the dehumidifier compressor supply, which automatically powers down when the Arduino ceases to function, allowing for normal dehumidifier operation. A 10k thermistor probe attached to the cold coils monitors the coil temperature, and every 15 minutes it opens the relay in the compressor lead if the coil temperature falls below 5C. The fan continues to run, defrosting the coil until the temperature exceeds 10C, at which point the cycle repeats. No adjustments are necessary. I initially considered incorporating a DHT11 to replace the internal controls and utilize two relays – one for the fan and one for the compressor. However, I ultimately decided that simplicity was the better approach.