Yeah, many of those sizing estimates for the units are best-case, sealed rooms with "typical" heat in "typical" climates. They also don't take into consideration room air leakage and heat types. Forced air heat, just for an example, is constantly pulling away cool/humidified air from the room, heating it (lowering the RH), then distributing it back into ALL CORNERS of the house. If you run a properly-sized humidifier in a situation like this, you are almost literally pissin' in the wind. Another example, if you have a large, open stairway or loft, that is where the heat flows, taking moisture with it. Bottom line is each house and situation is different and sometimes we can't just rely on the advertised numbers. If I had a forced-air system, I would certainly use an inline humidification system as the basis of my humidification plan.
We have forced air, and an in-line humidifier. Open concept main floor, large family room downstairs, stairs going up to the second floor, three bedrooms, hall way, bathroom. About 1400/sq. ft. The hygrometers usually never go above 40%, only if the temp rises above 0C, like 5 or 7 and if it's raining out. That is not typical of January or February on the shores of Lake Ontario on the Canadian side. Come to think of it, it's not typical on the US side either. In either case, my guitars, snug in their cases, properly humidified, are doing good. They just don't get played as often. I love it when the furnace is turned off, and they come out of their respective cases and go back on the stands for the next few months.
What's that off on the left? Picked this little guy up this afternoon for my home office where the acoustics stay (in their cases). See, we DO pay attention.
Quick google search is Cincinnati average annual 73% Humid summers dry winters..and a whole lot of bouncing around, which was my real point. I did not get real numbers sorry but if we need to break it down we should know the average Humidity inside our house where the guitars are. I don't know what they are in mine
Yeah, outdoor relative humidities can be extreme, but only loosely correlate to indoor RH because of fairly stable temperatures and trapped air indoors. You can get a fairly cheap hygrometer that can record min/max over time. That will give you a really good idea. Just CALIBRATE it first!
