>No really, a heater works by sending an eletrical current through a resisitor,
>and this (somehow) creates heat (and often light, usually dull red to orange).
>I don't know of any way to reduce ambient heat via electrical resistance.
			 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
I agree.  An electronics device which CAN cool things is available, and 
it obviously is more complicated than a resistor.  In my experience
they're called Peltier (pel-tee-AY) devices and they involve a special
semiconductor junction.  They usually take the form of a flat plate,
and often they are used in vacuum bell jars as a small platform on
which specimens may be placed.  This is convenient when you need to
cool a specimen while it's inside the vacuum bell jar.
Doug, perhaps your father was referring you to Peltier devices.  I
don't recommend that you use them since they would be very
expensive and inefficient for your application.  Perhaps you could
try a _gentle_ blower fan to help circulate the air.  Yes, I know
that you like to keep the humidity very high and that circulating
air may lower it.  If the circulation is gentle, though, and if
you have a lot of moisture in the sphagnum that can evaporate,
then the humidity will probably be high enough and the temperature
may be kept at a reasonable level.
					Perry