Whole room humidity control better than Dampp Chaser. ( Right?)

[Don]

Hi Terry,

The original DC back cover was 10 mil Mylar sheeting as part of their
"Ultra" system. Folks didn't "take to it" even though it worked very well
(I.E. better than "front side" installations) with no ill effects to
pianos. It worked on small Steinway uprights with no "nose hole" (i.e.
soundboard one solid panel no openings) with the controller on the inside
of the piano. From that I conclude that humidity does penetrate the sound
board a lot faster than most folks believe.

DC does hold a patent on the idea of back/bottom covers "for humidity
control". Home users may install their own without infringement, so I
suggest it to them.

Since you have a DC dehumidification system how about using your expensive
(and very accurate) humidity meter to do some measurements under the string
cover and inside the bottom cover? (Assuming you have the covers installed
that is).

So far as I am aware, no one has attempted to compare a DC controlled piano
with a Hivac only controlled piano, so there is no "proof" that Hivac
systems costing tens of thousand of dollars per room do a "better" job than
DC systems costing about one thousand dollars.

I believe if someone did do such a study that the DC system would improve
on the results that are possible with Hivac only.

My suggestions to upright clients are:

1. Fix the humidifier on your force air furnace (required by law where I
live). 
2. Add a back cover to your upright.
3. Add a dehumidification system that is controlled
4. Add a full DC system.

For Grand owners:

1. Fix the humdifier on your forced air furnace.
2. do not use a "set back" thermostat
3. Add a full DC system with bottom cover
4. Keep the lid fully closed when instrument is not being played *or* add a
string cover.

This builds from weaker to stronger and provides results of 4 cents pitch
change over 24 months for uprights (and 4 cents in 12 months for grands) in
a climate that varies from 4% to 84% R.H.

If anyone has measurements from a Hivac system that rival these figures
please post them. Until then don't assume that a "proper" Hivac system will
"do the job".

At 12:46 PM 2/18/2008 -0500, you wrote:
>I wonder if there is any danger of trapping too much water vapor in the
rear of 
>the piano with plastic covering the back? Hasn't DC experimented with that 
>previously? To the best of my knowledge, DC does not recommend use of
plastic as 
>a back cover.
Regards,
Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.
Non calor sed umor est qui nobis incommodat

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