After beating my head against a wall for most of the fall trying to get a used St. Croix useable, I've "tapped out" and bought a new Castle Serenity. I installed the thimble & sealed the pipe seams today, all seems well. The room is only 225 sq/ft. Do I need an OAK? I would guess I'll need the window or door open, to keep the heat down to a reasonable level or maybe I'll start and stop as needed. If an OAK makes things more efficient, even if a window or door is open, or makes it so I don't need to leave anything open, I'll put one in. Also wondering what the best setup/settings are to keep the temps down(don't hear that everyday).