Hey Tommy,
Listen Brother, I have that H20 heater in the bathroom, very small bathroom, like 32x 24. Just gave it a real world test at Sturgis, 9 days, maybe 10 or 11 hot showers and 10 cups of hot instant coffee. I have a little Heng's 1 speed fan/light combo in there and I can tell you, from experience, that there was ZERO PROBLEM venting the exhaust and heat. ZERO. In fact the gasses coming out are more like warm, NOT HOT. You have to run those in in short bursts anyway if you plan on taking more than one shower. So, you want to experiment with controls to find the correct temp setting BEFORE you jump in nekkid and scald your region, and the first 1-2 sec. will be cold, but then, its on Baby. Get your stuff all wet, 20-30 sec., turn off wand, soap up and scrub er' down as long as you need or want, whatever, then a good rinse 20-30 sec. and end it. That's probably 2-3 gals. or so. You don't have a lot of fresh capacity so you need to be efficient. JUST MAKE CERTAIN THE VENT LID IS OPEN AND FAN IS ON (exhaust or out) FIRST ! Also, mount that sucker close to the vent, but not too close. Mine is 5" lower than the plastic parts. If you are over 4'6" tall you probably don't want it aimed at your face, either.
Tommy, you know I love ya, and would never knowingly give you any bad advice, But you have to do what you feel is right for you and your family. You know where I stand now. Here's some pics.
McDave



