For starters I dehydrate mushrooms in bulk and I mean by the 5 gallon bucket load. My two so-called commercial 10 tray units were not able to keep up when they are coming in fast. That heavy flush is only for a few weeks but it is the bulk of the harvest. To that end I have been sketching the plans for a DIY large unit, being horrified at the current cost of materials. As luck would have it I came across this insulated cabinet I can upcycle into the most perfect thermostat controller dehydrator:
Funny how their ‘broken, free’ is exactly what I needed. Heck just to get more value for my footprint in the winter time it can double duty it as a bareroot storage cabinet. The inner space is around 20" x19" by 46" tall
Heating will depend on the amount of air flow I can run through it and I won’t know until I start measuring things. Some of the mushrooms I process contain an ungodly amount of water, said water was overwhelming my so called industrial dehydrators. Rather than move the humidity out it was condensing inside of the unit, steaming instead of drying.
Dry air is what dehydrates, more volume of air is better, temperature allows air to carry more water, but the more air flow the more heat it is needed to keep it at the desired temperature. I’m going to start with the guts from a 2,000 watt room heater and see what sort of air flow will maximize drying, while still being able to sustain the target temperature.
If you have skill and it still works you can reverse the freon flow and make it a heater. You can reverse with the pump or just switch the tubes around. More work, but would work the best.
Those racks might be an issue if you intend to reuse the originals. Just like a smoker you have to be careful that the rack is food grade so it isn’t leaching nasty chemicals into your finished product.
It is going to have about 20 racks so the 3 that came with it will be replaced.
This is where the quite significant cost comes to play… Nowadays a single sheet of expanded metal is ridiculously expensive, the racks are around 20 x 20, I can get 8 per sheet, so I’ll need 2 1/2 sheets. If luck shines on me, between now and the next season I’ll find them on Craigslist or Marketplace for around $100 each, or it would be $200+ per sheet. Food grade paint can also hit $100. Even with a $20 used room heater (which has heating unit, thermostat, overheating safety shutoff, and fan), to do it right I’m looking at $350~$600+.
Is it worth it? Well I could do it for a whole lot less if I can find a less expensive rack material. Bottom line is I want and I need to do it right because I do make a pretty penny processing and wholesaling mushrooms by the kilo, and this unit should be able to produce a full kilo of dehydrated mushrooms in one sitting. 20 racks is just north of 50 square feet of real estate. Then there is the fact that the ungodly amount of humidity was overwhelming the capacity of my industrial dehydrators, to the point where I had to drill venting holes and slits on them. Building it I can fine tune heat and air flow to the exact point I need.
