First let me say what I did, for the space I have, could have been accomplished with a large tub and the humidifer, fans, pump, light and controls. A tub laying around with everything hooked up to it was not really something I wanted. While what I have built I would not call stealth, it is discrete and that was what I wanted.
Second I would like to thank Microbe77 for his documentation on his greenhouse builds. I leaned heavily on his design.
Essentially this is a plastic storage unit that has been converted to house all the control features as well as the fruiting chamber. I used R5 and R4 foam panels to insulate the upper fruiting chamber section. I considered just lining with plastic instead, but my thinking is the insulation should prevent a temperature differential on the wall thus preventing excessive condensation. The insulation board is also very convenient for cutting and is easy to work with so I didn't have to attach it to anything, but rather I just overcut each section and forced it into place so that it supported itself during construction. Instead of plastic I opted to use 60mil TPO to line the walls and floor. It is a commercial roofing product so it should be much more resilient to things getting dropped and allow for some pretty rough treatment when scrubbing. The ceiling I just troweled on caulk. I like the all white as well. It feels cleaner and should make spotting issues easier. Deck screws with washers were used to fasten the TPO through the foam to the plastic container itself and spray adhesive was used to get a bond between the TPO and the foam insulation boards. (Note, spray adhesive will eat foam, but the panels are lined with a thin sheet of plastic making it easy enough to use the adhesive. Elastomeric caulk that allows for 70% expansion at the joints was used for the lining joints and screws, again durability was the goal. These items are much more expensive than I would have chosen to use if I was buying them solely for this project, but I had scraps left over from a project. Supporting the whole thing I (very roughly) roughed in a shelf to support the whole thing with 2x3 fencing rails and OSB screwed directly to the walls of the unit where the plastic was thicker. The shelf is sloped caddy corner to allow drainage.
I used wire shelving from a home improvement store and just cut the single shelf to make three shelves. They are supported with clips and deck screws into the plastic unit's walls, and cut down a metal tub and screwed shelf brackets in the front. the metal rods are held in place by the shelves themselves and just rest on the floor of the fruiting chamber. This allows the shelves to be rotated at the back easily so that I can clean the fruiting chamber easily.
I used a piece of dripedge to make a nice lip for the perimeter of the unit. This allowed me to simply use a piece of the foam panel cut to fit over the opening. Velcro seals the whole thing and makes the whole front panel removable, again for easier handling of trays and cleaning.
Light is provided by a simple LED fixture. After all the TPO was in place I just traced out for the fixture, cut out the TPO and foam, drilled a hole in the OSB shelf to run the wire down and then mounted the back piece, wired up the fixture, put the cap back over, and then caulked the whole thing up so that water will not get inside or behind. The LED fixture never heats up that I can feel with my hand or a temperature probe beyond the ambient temperatures so I am not worried about issues having it sealed up.
Two holes were drilled in the bottom, one is for the plumbing of the humidifier unit and the other is for the wiring for the fans and a drain. The bottom shelf is slanted caddy corner so at the highest point the humidifier enters and at the lowest point the drain sits. The humidifer is made of a 5 gallon bucket, a 12v small squirrel cage style computer fan, a length of hose and a 5 head fogger unit from house of hydro. I tried a cheaper single disk fogger unit, but it's mist output could not keep up with the fan, ultilmately providing very little humidity. The 5 disk unit provides enough mist to probably humidify an entire room. It is almost instant, making the humidifier itself incredibly efficient. Improvenments to be made are to replace the accordion style hose I have now with a smooth wall hose which will be cleaner and less maintenance. I used a simple flexible pipe joint with hose clamps to connect the hose to the bucket which has a hole cut and small plumbing piece threaded to it. No caulk was necessary for that.
Air is handled through the drain where again a plumbing fixture was threaded through the hole in the floor (osb shelf). I have a high capacity aquarium pump providing continuous fresh air and I wired up 12v computer fans to make sure air is circulating at all times and the fresh air outlet is being well mixed. I just used CAT5 scraps cut down and spliced into the computer fan leads to get the length of wire I needed. Splices were simply taped. The drain has a "filter" consisting of wadded up polyfill to allow for some air to escape, water to drain through, and provide an adjustable seal for the air line and wiring. This should prevent spores from exiting the fruiting chamber.
Humidity is controlled using an Ink-Bird prewired unit (IHC-200). The sensor wire was run into the humidifer and through it's hose to minimize cuts in the fruting chamber. The sensor is then suspended with a wire tie from the bottom of a shelf. I have the humidity set to 96% RH and to kick on at 95%. The reason for this is that the humidifying unit is so efficient, despite the speed of the humidity controller at registering humidity changes, It still pushes to 100%. The unit has an alarm when humidity is too high that cannot be turned off. An alarm coming from my fruiting chamber is not very discrete so this minimizes that.
Controls are handled with a digital timer for the light. It is set to come on for 1 hour 8 times a day, basically every 3 hours. The circulation fans run nonstop and are just powered by a spare PSU from an old computer that has since been used for parts. The air pump runs non stop and should provide 1 air exchange every 45 minutes when the chamber is full and 1 exchange every 1.25 hours when it is empty. Again the Ink-Bird IHC-200 controls the humidifier. Temperature is presently not controlled, but I do have a unit that I can use. I intentionally left the bottom uninsulated so I could mount some type of ceramic heat bulb in the controls section if I find sometime in the future I want to heat the fruiting chamber,
I have a small tub that has been making some short fruits in a dub tub which I attribute to a lack of humidity. It has been placed in the fruiting chamber along with a tub that has yet to pin. I will use these as I check things out and soon will be placing some larger trays in the fruiting chamber.
That's it. Now it's time to test it out and run it through it's paces to see how it performs! The whole thing took about a week to build, but all in all maybe 15 hours of actual work.
