Open letter to Dampp Chaser

[Kent Swafford]

Glenn wrote:

>I was about to buy one of these for myself until I learned of this
>"problem."
>
>Why not dehumidification ON when humidity reaches 45% and humidification ON
>when it reaches 35%  (adjust numbers to your preference)  all other times -
>NOTHING is on.
>
>Can the system be modified to accomplish this?  Is there a downside to this?
>
>Glenn.

Theoretically, an installation might be possible that leaves nothing on 
for several percentage points of relative humidity in the middle.  No, I 
have not actually tried this.  Such an installation would require two 
humidistats, adding to the cost of a system.  Dampp-Chaser has in the 
past had available "wet" and "dry" humidistats;  the dry one switches at 
a lower relative humidity than a normal humidistat and the wet one 
switches at a relative humidity higher than a normal unit.  If these 
humidistats are still available, one could install a system in which a 
wet humidistat controls the dehumidifiers and switches off several points 
higher than normal;  the humidifier could then be controlled by a dry 
humidistat and switch off several points lower than normal.  Nothing 
would be on in the middle.  To avoid any possibility of both systems 
being on at the same time, one could power one of the humidistats from 
the other humidistat, that is, if you plugged the dry humidistat that 
controls the humidifier into the humidifier outlet of the wet humidistat, 
the humidifier would only have power available while the dehumidifiers 
were off.

Dampp-Chasers have immediate short-term affects on piano tunings when 
they cycle, and it would seem that a normal system would cycle most often 
and impose these short term affects most often at the exact time that the 
least humidity correction is needed.  However,
I would caution that Dampp-Chaser has done extensive testing of their 
products, and I don't believe that one could assume that the above 
described installation would be necessarily superior to a normal correct 
installation.

Kent Swafford