A single-hose unit uses air from within the room to cool its condenser, and then vents it outside. This air is replaced by hot air from outside or other rooms (due to the negative pressure inside the room), thus reducing the unit's effectiveness. Wikip
Reduced it compared to what? If instead of air from elsewhere in my house, it used air from outside, that air is hot too. Hotter than the air in my house, at least during the day time, no? If it's below 72 outside, I'll open the window. (Yes, I know that lets the humidity in, but I've been known to do it anyhow.)
Also the article distinguishes "Hose systems, which can be monoblock or air-to-air, are vented to the outside via air ducts. The monoblock type collects the water in a bucket or tray and stops when full. The air-to-air type re-evaporates the water and discharges it through the ducted hose and can run continuously."
Here's a place where they should be referring to reduced effectiveness, right? Re-evapping the water has to be inefficient, yes? Can't I just use one that colllects the water and also has a drain, and drain it to the shower drain in the next room? Or if that won't work, my whole room overhangs the first floor by about a foot. That's where the cable tv comes in, under the overhang into the closet. I can drill another hole an inch from the cable tv and run a hose out of that, right? Just let it dangle or drill a hole in the downspout and run it into that, then seal around the hole.
Last year I didn't mind no AC, only 8 really hot days, but this year I've been dreaming that it's hot, even when it's not. Maybe I should take precautions.