Al is right, if water goes out as a vapor, the its heat of vaporization goes
out with it.  This is inevitable unless one equips the hive with a condenser
to recapture that heat.   Apparently, from what George and Blane indicate,
you can have your vent up high, even in a rough climate, and the bees do
fine.  Seems like the critical thing is venting the bad stuff, and that's
good for everyone to know.  What I wish to learn is how to optimize letting
out the bad stuff without letting out more heat as heated air than
necessary.  Heat is wear on my bees, and honey.

Bill Morong