Air circulation question

Question from growers who grow in enclosed spaces: I'm in the process of repurposing a 48" long by 36" high by 24" deep bakers rack that I used for growing my plants, completely enclosing it for growing orchids in more climate-controlled conditions my living room. It has actually been a pretty easy project, and I'm planning on using 112 CFM muffin fans for circulation. How many fans do you think I might need for that size space? I was thinking four, two for the upper shelf and two for the lower, pointed down into the tank. Would that be sufficient? Overkill? Thanks! -Stephen

 

In progress. Shelf is 48" long x 36" high x 18" deep. Lights are a six-bulb T5 unit. I ordered three muffin fans, one for each top rear corner and one for under the middle shelf. Rear panels are corrugated plastic sheeting, and the top is clear plexiglass. Thicker plexiglass doors are being cut, and I will run a cool-mist humidifier into the unit through a vinyl hose at the rear. It's not airtight by any means, but hopefully will contain most of the moisture/humidity and provide a more controlled environment than I've had in the past. Should be up and running in a week! -Stephen

 

All done. It's filled with around 50 different Dendrobium species, and some assorted other plants. The ultimate plan is to make it an all-Dendrobium tank. I have a cool-mist humidifier attached to the back with an aquarium hose, rigged up on a timer, coming on once an hour for 30 minutes. Temp is an even 76 during the day, and humidity varies between 65% and 85%. Not sure if there will be enough light for the plants at the bottom back (mostly Angraecoids and Bulbos), and I may need to add a smaller third fan on the bottom of the middle shelf. Half the fun is in the tweaking!

 

Not sure yet. This is the first day with all the plants in. I could experiment with opening the doors if it doesn't drop 10 degrees or so, but then I'd lose the humidity. It's in my dining room, so it's pretty much at the mercy of the ambient room temperature.

 

Marni, I noted about an eight-degree temperature drop last night. In the winter it will be more like 15, as I don't keep the house much above 68 during the cold months.

 

Possibly obvious question: I've got the humidifier on a timer to come on once an hour for 30 minutes. At night, the humidity inside the tank goes way up, hovering around 90% and staying there. Might it make more sense then to adjust the humidifier's timer to come on less frequently at night, say every 60 or even 90 minutes? That would also save on having to refill the humidifier as often.