<html> <body> My wife and I regulate humidity (in winter) through the whole house with two humidifiers and a gauge on a bookshelf by the piano.  This requires some attentiveness, and is affected by outdoor weather.  The problem comes when we travel.  We were away over the holidays for two weeks and when we returned the humidity was in the high single digits.  The piano sounded horrible.  We got humidity up in a few days and in two weeks I retuned.  We have developed a rather low-tolerance for out-of-tune.  The issue is practicality.  Most customers will not go through the trouble of monitering RH and refilling, turning on/off their humidifiers on a daily basis.  Once a piano is up to humidity, the DC will usually last a week often more, it only has a small environment to keep-up.  The humidity migrates through the wood, even in a grand piano pin torque is affected (closed lids do help in extreme environments).  Buying a room humidifier that has a remote-control humidistat will cost more than a DC system, although it would benefit all the wooden furniture too.  I have discussed this with clients and some have chosen to get a cheap hardware-store hygrometer and start running a room humidifier.  They last about halfway to the next tuning and then want a DC system or believe they can tolerate the effects on the piano. Andrew Anderson Las Cruces, NM At 06:40 AM 1/13/2004 -0500, you wrote: <blockquote type=cite class=cite cite>I don't think anyone is questioning the effects of RH changes on the tuning of a piano.   I'm with Sarah and feel that proper full environment humidity control is the best way to go - better than a full DC installation.   I think where the arguement comes in is the fact that probably 99% of full environment humidity control systems are improperly designed, poorly functioning, turned off and windows opened up, turned off over the holidays and summer, etc., etc.   But this does not change the fact that if one installs a proper full environment humidity control system that holds the RH constant within a few percent, it will be more effective than a full DC.   And don't forget that even if you hard-wire the DC system into the wall, who is ever going to notice that the circuit breaker tripped 15 months ago and the piano hasn't had any humidity control since that time?   In my shop I have a Sears basement-type dehumidifier. It keeps the shop right at 45% RH (within a percent or two). I never varies. How in the world is a DC unit on a piano in my shop going to work better, or do anything at all besides vapor, dry, vapor, dry, vapor, dry, etc., etc.?   So I guess the bottom line is that if one is willing to set up a proper full environment humidity control system that holds the RH constant within a few percent, that is the best way to go. From a practical standpoint, knowing that 90-some% of full environment humidity control systems are not going to be real effective, the full DC-type system is the way to go (they DO work quite well). And as someone pointed out, from a practical standpoint a full DC-type system in a piano which is in an environment modified by a full environment humidity control systems is the best around.   Flame Suite Tighly Zipped,   Terry Farrell   ----- Original Message ----- From: "DIANE HOFSTETTER" <<a href="mailto:dianepianotuner@msn.com">dianepianotuner@msn.com</a>> To: <<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>> Sent: Tuesday, January 13, 2004 2:51 AM Subject: Re: Where did the RH Go > Sarah, > > For fourteen years now my partner and I have been measuring and graphing the > tuning on every piano immediately before we tune it.   We also record the > relative humidity and temperature most of the time, whether it has a > Damppchaser installation or not, and if it is functioning correctly. > > Then when we next tune the piano and record all the data again, we have a > way of understanding how to service the piano to make the tuning as stable > as possible. > > Over the years I have had fun with a variety of experiments.  One day I > arrived to tune a piano in a room that is routinely kept unheated with no > climate control in the piano.  The maintenance people had just turned on the > heat before I arrived and a stream of warm area was shooting out of the > register about ten feet away. > > I was dismayed; the heat should have been turned on hours before.  I knew > the tuning could not be reliable.  I went ahead and graphed the tuning.  As > soon as I finished that graph, I remeasured the tuning and graphed it again. >   Then I remeasured and regraphed, and then once again.  I ended up with a > graph showing four distinctly separate lines of the tuning as it changed > with the relative humidity and temperature for each line carefully recorded. > > There is no question in my mind that changes in relative humidity affect the > tuning dramatically and that a Damppchaser system does an excellent job of > helping control that.  I have numerous graphs to show it does. > > Diane > > > > > > Diane Hofstetter > > > > > > >From: "Sarah Fox" <<a href="mailto:sarah@gendernet.org">sarah@gendernet.org</a>> > >Reply-To: Pianotech <<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>> > >To: "Pianotech" <<a href="mailto:pianotech@ptg.org">pianotech@ptg.org</a>> > >Subject: Re: Where did the RH Go > >Date: Mon, 12 Jan 2004 21:48:30 -0500 > > > >Hi Don, > > > > > I did not say your system didn't work. What I said was a DC system would > > > work even better. > > > >Perhaps.  Perhaps not.  I don't mean to be argumentative on this point.  > >I'm > >really asking a question here:  Have you (or has anyone else) done > >measurements with a good, accurate hygrometer on a complete DC grand > >installation, during dry ambient conditions, showing that humidity is > >indeed > >evenly distributed all over the soundboard, both under and on top, and in > >the action cavity?  Also, have the same measurements been done inside the > >piano with a closed lid and inside the action cavity during predominantly > >dehumidifying periods?  In other words, are DC's claims fully > >substantiated, > >as determined empirically with a hygrometer?  I've heard lots of claims > >regarding stability of pitch.  That's all well and good, of course. > >However, how well does the DC system regulate humidity (in contrast to > >pitch)? > > > > > I do recommend room type humdifiers as well--but only to "assist" a DC > > > unit. If it is a choice of one or the other the DC provides much better > > > year round control than is generally possible with a room type. There > >are > > > exceptions, but they are very rare. > > > >This sounds like a reasonable approach. > > > > > Do you have measurements for the summer time? Where I am I have > >documented > > > as low as 4% and as high as 84%. > > > >Without humidification, humidity levels inside my house vary from 27% in > >the > >winter to 67% in the late fall.  I have forced heat and refrigerated A/C, > >BTW.  I suspect humidity levels are far different in other parts of the > >state.  I'm in Central Ohio.  In the lake areas, humidity is undoubtedly > >much higher during moderate weather.  Also, I have no idea what humidity > >levels occur in other people's homes here in Columbus.  (I don't service > >their pianos. <grin>) > > > > > I would love to have a controller for a DC type system that had much > > > narrower limits. I know, for example, that rare bird hatcheries have > >units > > > that are calibrated to 1/10 of one percent humidity that power an > > > "electronic" fan (read no blades--some sort of vibrating plate) combined > > > with an ultrasonic humidifer. I'd love to get my pinkies on one! > > > >Well, I can't boast 0.1% limits with my system (WOW!!), but I do quite a > >bit > >better than the specs DC boasts.  I did a 100% non-DC-brand installation on > >my concert grand, using a GE humidistat that cycles the system adjustably > >between 40 - 44% (or occasionally as widely as 39 - 45%) when the ambient > >RH > >is in the upper 40's.  The installation is fairly recent, so I haven't yet > >been able to observe its behavior at higher humidity levels.  I'll give you > >an update in the spring if you're interested. > > > >Peace, > >Sarah > > > > > > > > > >_______________________________________________ > >pianotech list info: <a href="https://www.moypiano.com/resources/#archives">https://www.moypiano.com/resources/#archives</a> > > _________________________________________________________________ > Scope out the new MSN Plus Internet Software - optimizes dial-up to the max! >    <a href="http://join.msn.com/?pgmarket=en-us&page=byoa/plus&ST=1">http://join.msn.com/?pgmarket=en-us&page=byoa/plus&ST=1</a> > > _______________________________________________ > pianotech list info: <a href="https://www.moypiano.com/resources/#archives">https://www.moypiano.com/resources/#archives</a> > </blockquote></body> </html>