Dampp-Chaser Climate Control System Operation

[Bdshull@AOL.COM]

Roger:

Through your post I learned, among other things, of the availability of a wet 
and dry humidistat;  that is good news - thank you!  Are these available in 
North America?  Certainly I will want to use a wet system for the many pianos 
which my clients bring from the Far East, correct?  However, why not make a 
humidistat that is "wetter"?  It is my understanding that in parts of this 
world a higher RH is considered standard (I believe Neupert uses a reference 
of 60% RH, for example.)  And 50%RH is still quite a bit less then the 
Australian region referred to in the post in this thread, as well as the 
pianos we see from Asian climates.

I've wondered about this for some time, and am quite interested in your reply.

Bill Shull
University of Redlands, La Sierra University

In a message dated 2/3/00 8:26:38 AM Pacific Standard Time, 
DamppChaser@compuserve.com writes:

<< Hello list,
 
 I have been travelling outside the US on business and it is not always so
 easy to get email, so it is just now that I am able to read of all the
 interest in Dampp-Chaser.  I am Roger Wheelock, Vice President of
 Dampp-Chaser Corp. and will do my best to respond to the technical issues
 under discussion.
 
 We develop our Systems using actual averages of sound board moisture
 content in pianos in our research test rooms.  We maintain test rooms at a
 constant 70% and constant 20% relative humidity (RH).  Without a Climate
 Control System the moisture content of the soundboard varies when exposed
 to these extreme environments from a high of about 11% (at 70% RH)  to a
 low of about 5% (at 20% RH).  With a System installed soundboard moisture
 content range is reduced from 6% to 1% or less.  Some of our best systems
 will show 7.5% average soundboard moisture content when the test room
 environment is at 70% RH and only drop to 7.3% average soundboard moisture
 content when the test room environment is changed to 20% RH.  It is this
 control of soundboard moisture content that provides pitch stability to the
 piano, and allows a technician to perform a finer, higher quality tuning
 after the System has been installed.
 
 The System actually creates its own environment within the body of the
 piano.  An electromechanical switch with a humidity sensor band ensures
 that the dehumidifier and the humidifier continally cycle while the system
 is operating.  This provides the control to maintain a constant environment
 even if the room environment is very humid or very dry.  The switches in
 the humidistat are all precailibrated in another test room at the factory. 
 Here, in a twenty hour period the humidity is gradually raised to around
 60% RH and then lowered to 30% RH.  Computers record the high and low set
 points for the switch.  Switches are calibrated as necessary to ensure that
 specifications are met for either a normal, wet or dry humidistat.  The
 average of the two set points falls in the following ranges for each type
 of humidistat.
 
 Normal = 42-44% RH
 Wet = 48-50% RH
 Dry = 36-38% RH
 
 Each humidistat has differential between the low and high set point of less
 than 8% RH.
 
 The wet humidistat is designed for pianos which have been in a humid
 environment for a long time.  The dry humidistat is designed for pianos
 which have been in a dry environment for a long time.
 
 Regarding dehumidifiers, we recommend a 50 watt and two 25 watt
 dehumidifiers for a grand piano which is longer than 6 feet 10 inches, a 50
 watt and a 25 watt dehumidifier for smaller grand pianos, and a 50 watt
 dehumidifier for vertical pianos.
 
 If any of you have further questions please contact me directly.  I can be
 reached for the next seven days at DamppChaser@compuserve.com.  After that
 I can be reached at roger@dampp-chaser.com.
 
 Thanks,
 
 Roger  
  >>