[CAUT] Topping up the tank

[Mark Cramer]

Light fixturesHi Dave,



you raise a good point, I'm no authority, but will share what I think I know
about overlapping thresholds, then hope someone in the know will set us both
straight.



1.) This may be a stretch, but I've been told a proven method to regulate
the temperature of blood resource in a blood bank, is to cycle slightly
warmer and cooler air through the storage unit, overlapping in the critical
temperature range.



Why they can't simply dial in a thermostat at the temperature they want, and
a get stable temperature... I don't know, I'm not an engineer.



2.) Closer to home; over winter, I finally completed the heating/cooling
system (ductwork, furnace, etc.) at our cottage. Tom K., our mechanical
plant supervisor suggested the most efficient operation (we heat it all
winter) is having the furnace-fan run at low-speed continually, with the
furnace actively cycling in warm air in as required, rather have everything
shut off until it gets cold, then try heat it all up again. Make's sense,
and it works!



Granted Dave, neither of us are enthalpy control experts (I sure ain’t), but
I hope we realize piano climate systems don't "force" humidity in or out,
that should be fairly obvious. You might find a conversation I had with Bill
Spurlock about water-damaged pianos helpful:



Bill explained that warming and circulating air adjacent to moist wood
creates a gradient, or in simple terms makes the air a more inviting
destination for the moisture, than the wood is. This gradient invites the
moisture to change directions, and move towards the more welcoming
environment.



Likewise, to restore equilibrium moisture content to wood, simply provide
moist air in the vicinity... no “forcing” required. If the wood is dry it
will accept moisture, if it isn't, it won't.  By the way the most satisfying
explanation I’ve ever encountered on this subject was the class Roger
Wheelock gave at the Dallas Convention. Roger of course is a scientist, and
Bill I believe, has an engineering background. Isn’t it nice the PTG has
such good resources, so we don’t have to “guess” about this stuff?



As for tempering the climate around pianos, I think all we’re really trying
to do Dave, is maintain the equilibrium moisture content in the wood
(soundboard), to keep the piano at pitch and prevent damage.  And it seems
we can do this quite successfully, using the products you mention, to
maintain a compatible range of relative humidity in the air.



An “Inconvenient Truth” as you and I both know, is if relative humidity isn’
t stable, the moisture content of the wood will not be stable (“Nature’s
Law,” not ours), and if the wood isn’t stable, neither is the tuning, no
matter the manufacturer, the day of the week, where you live, who tuned it,
or which foot they stood on.



(I used to think piano owners/sales persons were the biggest perpetrators of
"piano-tuning myths,” but you might be surprised at the fanciful notions
some of “us” have cultivated
 myself included!? Yipes! ;>)



Anyhow, people who understand wood, know “the rules,” and hopefully we do
too, since pianos are made of wood. For what we don’t know, it’s fortunate
to have a wealth of knowledge and experience in the technology and
manufacturing fields we can rely on.



best regards,

Mark Cramer,

Brandon University



PS Regarding things that “do” work:



Last year ago I sent a post about fitting a soundboard cover to a KG-3c, in
a church that had 30-cent seasonal pitch swings, despite having a
Dampp-Chaser with one 50w and two 25w dehumidifiers.



I tuned the same piano this morning, and was pleased to find the tenor just
6 cents sharp, and the rest of the piano right on the button!













That’s the one thing (or one of the things) that I don’t get about these
systems.  I’m fortunate that our climate here is sufficiently benign that we
don’t have any systems installed.  As the system is currently designed, it
forces humidity into the piano – even when the ambient humidity is high –
and then forces it out.  To me it would make more sense to have the
humidifier come on at say 35% and the dehumidifier to come on at 50% (45%??)
but in between those it would leave the poor piano alone!  Or in the summer
if your humidity is high, just disconnect the humidifier and the opposite in
the winter.  What good is it to continually humidify then dehumidify the
piano probably several times a day?



dave


David M. Porritt

dporritt at smu.edu



  -----Original Message-----
  From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org]On Behalf Of
Porritt, David
  Sent: Thursday, June 08, 2006 10:19 AM
  To: College and University Technicians
  Subject: Re: [CAUT] Topping up the tank


  Jeff Tanner wrote:



   
 and even in these high humidity summers the tanks need filling more
often than every two weeks -- more like a week to 10 days.



  That’s the one thing (or one of the things) that I don’t get about these
systems.  I’m fortunate that our climate here is sufficiently benign that we
don’t have any systems installed.  As the system is currently designed, it
forces humidity into the piano – even when the ambient humidity is high –
and then forces it out.  To me it would make more sense to have the
humidifier come on at say 35% and the dehumidifier to come on at 50% (45%??)
but in between those it would leave the poor piano alone!  Or in the summer
if your humidity is high, just disconnect the humidifier and the opposite in
the winter.  What good is it to continually humidify then dehumidify the
piano probably several times a day?



  dave


  David M. Porritt

  dporritt at smu.edu
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