Note: Please see my Version 3.1 post for the current design: Link
Whew, what a journey and learning process in figuring out the recharging system for the silica beads. So much trial and error of drying mechanisms – note to self, do NOT install a thermal switch when testing resistor combinations – it seems the time consuming process of swapping resistors and wiring configurations of the resistors is a waste of time when the thermal switch does it’s job… Lesson learned. Ultimately after many hours of testing and experimenting I was most happy with 3 sets of three 330 ohm resistors in series (nine resistors total). This results in the 175 degrees (f) on the hottest spot of the outside of the PVC tube.
Assembly of the Silica Bead and Heater vessel:
Drilling the 4-40 holes for mounting the resistors
Tapping the 4-40 holes for mounting the resistors
The final assembled resistor heater attached to 1-1/4" flat bar
A baffle was fabricated to direct the moist air away from the humidity sensors
With the baffle installed (PVC glue with epoxy), there is a gap on the bottom and in the distance allowing dry air to flow while keeping water droplets away from the sensors
Gluing the power cable to the recharge tube
In the exhaust end of the desiccant drying tube has a 1-1/2" end cap with holes drilled and a stainless mesh to prevent silica beads from entering the baffle tee
Silica beads fill the recharge tube while the resistor heater is kept centered in the tube
Stainless mesh is the first layer to prevent silica beads from entering air gap
Stainless steel scouring pad to prevent silica beads from entering air gap
Wires connected using wire nuts to allow future servicing
The stainless steel mesh on the inlet side of the tee fitting condenses the moisture and flows it away from the sensors
The two sensors on the dry air outlet side (Wifi Temp/Humidity and Recharge Outlet (Humidity)
Stainless steel mesh keeps the sensors from moving around, while allow air to pass
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