Hey Jwalker, sorry for the seriously tardy reply, son was out of country and lots of other things, haven't been on in quite awhile. Apologies.
This is essentially a copy from another post, updating info. Also, apologies for the doubleposting, hopefully in two relevant threads. No, not a farmhouse, just a home with a good basement. Here goes:
I'm using a coolbot. Not a fan of trying to add humidity with a standard AC, but of all the things I've considered for this situation (small room, and we rent, we don't own), this seemed the least intrusive, least costly, and most portable method of all the things I've considered. The hole seen was from my initial window AC - one left behind when we moved in. It was clearly undersized for this room, which is about 6'x6'x6'. I've bought a GE 14,250 BTU AC, guided by the coolbot company recommendations.
Also, unhappy with the velocity output from the AC, I put together a ductwork system - a jury-rigged housing over the AC outlet, 2" PVC rise to 2"x 4' PVC run along the ceiling, holes drilled into the pipe and a fabric air-sock, after a fashion. Air nicely slowed and evenly distributed.
Humidity is particularly frustrating. My digital evaporative humidifier, controllable to 90% RH, is no longer made. It worked very well in my refrigerator-caves, but it's undersized here. I did try to add a couple ultrasonic humidifiers, but they didn't do anything. I believe they, too, were undersized. Some good guidance by Pav led me to think on adding in two more for a total of 4, but the cost of acquiring daily distilled or RO water in the quantity I'd need is $4-5 daily, not something I want to do.
There is an atomizing unit, the "
Hermmidifier", recommended by Peter Dixon in his materials. It's a perfect solution - particularly intrigued by teeing into my duct/air sock line, another great suggestion provided by Pav (thanks, buddy). But the unit requires hard plumbing and electrical that is likely beyond what I can do in our rented house.
I bought
this and will likely just control a large evaporative, wick-based whole house humidifier. I've had some durability issues with this type of sensor so will likely commit to a serious,
ceramic sensor, once recommended by Francois. Fingers crossed.