Actually, no.  Catalytic heaters give off two combustion waste products,
carbon dioxide and water vapor.  I use catalytic heaters in my RV which is
my full time home.  I leave them running night and day in the winter and
love them.  They are efficient with gas, give radiant heat and use NO
electricity.  At least my Olympian heaters use none.  I always leave a roof
vent open  (a 14" x 14" vent) at least one and a half inches on the open
edge, more if I've got both heaters really cookin'.  I'm talking about
heating a 35 foot long trailer, of course.

Scott

From:    "M.R. Nimmo" <mrnimmo@YAHOO.COM>
Subject: Re: Cold-weather camping/propane heater

>  They always were weak in heat and produced
a ton of moisture.  The Black Cat produces more heat
and less water

Isn't condensation a product of how well the heater
warms the interior (and creates temp differences on
the cold windows etc.) and the amount of moisture
inside the bus (heavy breathing)?  Popping the top or
opening a window just a bit helps by circulating some
of that cold dry air and removing humidity, right?