There are a couple of other products you might consider also.  If you
want to monitor the heat/humidity under the piano there is a product
called the Dickson Data Logger.  I have mounted this unit in some
pianos to record the changes in temperature and humidity for a given
period of time.  You can then hook up the data logger to your computer
and download the information.  This will produce a graph showing the
variation of the humidity and temperature for whatever period of time
you set it for.  You can set it to record as often as every five minutes
or up to once a day.  This will show you if humidity is a problem.

There is another product in addition to the Moisture King.  It is
a little more sophisticated than Moisture King.  It is called Dampp
Chaser.  They have distributors in many countries around the world.

Clarence Zeches