Today, I printed and assembled a fully integrated 3D model for the dry box’s heating unit. The 150W PTC heating module was mounted into position, and I fixed a small fan behind it, configured to push air through a sealed air duct directly into the PTC module. The heated air then exits straight toward the inner wall of the sealed container, where it’s expected to rise, circulate around, and eventually return from the other side – forming a natural hot air convection loop inside the box.
To verify whether this airflow path is effective, I placed the TH Elite’s temperature sensor at the furthest downstream location—the bottom corner on the opposite side of the container, furthest from the fan and PTC. This should help me determine whether the heated air reaches all corners and completes the loop.
Unfortunately, the test results were disappointing. First, I noticed that the temperature increase reported by the TH Elite was extremely slow. At the sensor’s position (bottom-right corner of the container, as shown above), the temperature never rose beyond the low 50s°C, even after extended operation. Meanwhile, on the other side of the container—near the PTC module (bottom-left corner in the diagram) – the heat was far too intense. The temperature was so high that it even started to soften and deform the 3D printed components near the heating zone.
To confirm this, I used the SNZB-02LD sensor with a metal probe to measure the actual temperature near the PTC. The reading climbed continuously and eventually exceeded 120°C, causing the sensor’s screen to display “HH”, indicating that the temperature had gone beyond its measurable range. Yet at that same moment, TH Elite still reported only 42°C, showing how uneven the thermal distribution truly was.
I believe the 150W PTC module I used this time was simply too powerful. Without sufficient heat dissipation, the temperature around the module rose dangerously high—
enough to damage the surrounding printed parts, and potentially the filament being stored. It’s clear that I should step back to a 100W PTC, which had previously shown more stable and manageable performance.
Another issue is the fan I’m currently using – its power is likely too low to move enough air through the entire box. It seems unable to establish a complete circulation path, which is necessary for maintaining thermal balance across the space. In the next version, I’ll consider either using a higher-power, higher-flow fan, or strategically placing multiple small fans inside the structure. The goal is to form a more reliable airflow loop that evenly distributes heat throughout the enclosure. I also plan to place multiple temperature sensors at different positions inside the container in order to accurately track the temperature differences across the space during operation.
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