variable humidistat

[MITCH KIEL]

      The other day, I was leafing through a catalog from a local firm called
Fungi Perfecti that supplies mushroom-growing supplies and info. They're located
here in Olympia WA (tel 360-426-9292). Their catalog describes a humidistat that
can be set to various RH settings from 10% to 99% with a tolerance of 3% to 5%.
It sells for about $160, and is made by Dolman, model HC 201. It draws 8 amps
and appears to be larger than Damp-Chaser's humidistats.
      I'm not suggesting that we all quit piano work and start growing magic
mushrooms, nor am I suggesting that this humidistat would be suitable for piano
climate control.
      What intrigues me is the *concept* of variable humidistats. This topic
was partially addressed recently by Bob Mair of Damp-Chaser who last week who
described a "smart" humidistat that senses low outside temp and adjusts inside
humidity according to industry recommendations.

      To those of you in climates with wide RH swings: Would a variable
humidistat such as the Dolman be useful in certain situations, such as concert
halls where the piano storage room RH does not match the hall's? Is there a
disadvantage to using the high wattage heating rods necessary to drive the RH
down to Damp-Chaser's fixed range of 35% to 45%? Would it ever be advantageous
to set RH levels to parallel ambient RH but at a smaller amplitude?
      I should mention that here in the Pacific Northwest we don't need
humidity control near as much as other climates -- we NEVER install humidifiers
--  so my experience is very limited. But I thought I'd mention this as food for
your hungry thoughts.
      Comments?

      Mitch Kiel