I need to get a portable dehumidifier for my garage. So mold won't grow in there, I want the humidity to be below 50%. It's only about 300-350 sq. feet. But, it's unheated. It doesn't get terribly cold there in the winter, because the furnace is in there. I don't put on a jacket to go in my garage in the winter. But it would get below 65 F certainly. Maybe it's about 45-50 F in the winter, although a dehumidifier would warm it up.
And I'd still like to keep the humidity below 50%, even when it's cold. The effect of warming outside air at 0-10F to 45F would naturally dehumidify the air. The water capacity of air at 10F is about 1/4 what it is at 40F. As long as humidity isn't getting into the air from some other source, I might not even need to worry about it. Unfortunately I haven't measured the humidity there in the winter.
The garage is half basement (my house is on a hill). The basement wall doesn't seem to leak significantly. Maybe there's a little water in the corners if it rains a lot, but not much.
I'm putting new seals on the garage door, the old seal is leaky.
How big of a dehumidifier do I need in there? I wonder if it would actually be energy efficient to put a heater in there so the dehumidifier would work better? Probably not.