Background: It's winter in Chicago and I have radiator heat, so it's really dry. The last 5 years I ran a direct water line to a greenhouse humidifier in my living room, ending in a small disaster, but that's another 'truly tangent'.

 

So this winter I purchased a standard $100 house humidifier from Menards and installed a float fill valve to save daily filling. There was already a hole in the back that just begged to drill for the valve. But was that the correct level?

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The float can adjust the water level 5" to 7.5" (which is the max-fill line). At the max fill line, about 4.5" of the 12" tall wick is exposed.