Autofilling Humi for Walk In

Matt,
Sounds like you have a fun project. The measurements given are 300 cubic feet. As someone suggested the Trion 707 would be overkill. It is a centripetal device, which means it makes fairly large droplets- with probably not enough room to evaporate before hitting something & soaking it.

Other choices would be a simple evaporative type of humidifier with 3-5 gallon per day output. We use off the shelf humidifiers as well as custom systems & match them up to the digital Set & Forget control for tighter control (2%) of RH. Advantage is low cost & easily maintained. Can be fitted with autofill.

The ultrasonic fogger is very intriguing. I am very familiar with the Habitat Ultrasonic, which can run $$$$ for a walk in, but have heard they are quite efficient. This is the first time I have seen Ultrasonic heads with reasonable output at a civilized price. I am going to order one of the larger ones just to play with. I don't have much information on which of these sizes would work best, but given the low cost, one with 3 heads & 1500ml output would be a good start. If you have a good sensitive control, higher output won't hurt you. Too small & it will never keep up or turn off.

To do auto fill get a 4-5 stage R/O system, not just a filtration system. There are dissolved minerals that will trash out whatever humidifier you get in very short order with improperly treated city water. Most need to be near a drain to offload excess water.

You can use the dial type analog control for humidity-they are inexpensive, but digital will allow for a tighter control of range. Most tape type dial sensors have plus-minus ranges of 4-8% and have a lot of fiddle factor to dial in. I am biased, but I would never trust an analog sensor control. I used them before digital was available & they can be a challenge to maintain tight ranges of RH. Some work well, others drift quite badly.

Have fun with it.

cheers,
Bob Staebell