Hi Sarah, Two words. Bottom Cover. The effect of the bottom cover is to remove air "mixing" which you are providing with your ceiling fan. There are many posts in the archives about humidity control. In an "ideal world" we would be able to control humidity perfectly in the room. Unfortunately this is rarely possible. At 10:49 AM 4/11/2003 -0400, you wrote: >Hi all, > >I've been reading the soundboard torture and killer octave posts with >considerable interest. One of the results of these posts has been a lot of >comments to the effect of, "It surely goes to show how important it is to... >(insert some climate control maxim here)." > >This has all started me to thinking about the climate control situation >around my own piano. You see, I have a very difficult house. Unless I were >to put my piano up against the fireplace or in the kitchen against the sink, >I have no usable interior walls. Perhaps a bedroom? I think the piano is >bigger than any of the bedrooms, aside from the upstairs master. Bathrooms >are not a likely option. > >Kidding aside, my exterior walls are my only option. They are each around >75% glass (double-paned) and are where the heat registers are located. I >realize exterior walls are not as significant a problem for a grand piano as >an upright, but should I still be concerned? Of course I took the >precaution of blocking the heat registers in the room and allowing the room >simply to get the cross-flow from the adjacent rooms -- still quite >comfortable. I spaced the piano about 2 feet from the window, and I have a >ceiling fan in the room to keep the air stirred/mixed. During the dead of >winter (Ohio), I have insulated drapes for protection. Is anything about >this arrangement problematic??? > >I am also about to install climate control devices. I will be putting a DC >dehumidifier system in the piano for the moderate months. (The piano will >soon be making a move to a warm, humid climate, so I will definitely need >this.) I am left wondering about the humidification end of DC's system, >though. I'm not sure I entirely trust the thing. I'm also left wondering >whether a tiny column of water vapor from the humidifier will really spread >over an entire sounding board and not just condense in the middle and/or >waft away. The system also presupposes that the moisture doesn't just >evaporate back out of the board on the top-side, resulting in a MC still >somewhat less of where it should be. Finally, it appears to me that the >heater bars and humidifier would be alternately fighting each other in the >complete system. Is it really smart to heat the board during dry >conditions, even if the (tiny) humidifier is also adding moisture? Would >this not speed moisture loss on the top side? It doesn't compute. > >It seems to me a much better approach would be to humidify the area. My >house dropped to a low of 28% RH this winter -- not so low as to throw me >into a panic, but low enough that my piano complained somewhat. Anyway, the >DC system cycles over about a 12% RH range, as I recall. It would only take >an additional 8% RH to put my house at the low end of this range. Fifteen >percent would put my house in the middle of the range. Would this small >amount of added humidity really pose a problem for my house? > >I figure I could humidify the house to a minimum of 40% RH, using a >whole-house humidifier/humidistat system. Then the DC heater bars could >kick in during higher humidity conditions to drop the microclimate RH to its >36-50% RH range during the moderate months. There would of course be no >heater bar activity during the winter. > >If I opt for whole room (vs. whole house) humidification, how far away from >the piano should the humidifier be? (I would be using an ultrasonic unit >with distilled water.) Remember that I have a ceiling fan to keep the air >slowly stirred. > >Misc. concerns about the DC: > >The same would be true of the dehumidification process as the humidification >process: Heat would escape the soundingboard from the topside, and so the >effective temperature of the board would be roughly the numerical average of >the air temperature above and below the board. Thus, the board would not >really be kept at its target MC. The error would increase in direct >proportion to the overall magnitude of correction. Let's say the ambient RH >is 100%, and the DC system raises the underside temperature to achieve an >ambient RH of 42%. The net effect, I believe, (making liberal assumptions >here) would be an effective overall RH of 71% in the microclimate >surrounding the board. If there were also a heater bar under the closed >lid, conditions would of course be better. It seems to me that the DC is >only really effective at fine-tuning the RH. Perhaps the prudent piano >owner would also keep a room/household dehumidifier/humidistat running to >keep the RH down to a max of, say, 60%? > >In the grand installation, there's no heater bar behind the action, under >the pin block. Why? Would it not make sense to have a second humidistat >and heater bar -- perhaps attached to the backside of the action? >(Incidentally, the need for keeping the MC of my pin block and action parts >up during the winter makes me believe all the more in whole-room/house >humidification.) > >I don't know if I'm being too compulsive here, but the little soundboard >torture experiment.... Wow! > >Any advice and/or perspectives would be greatly appreciated. > >Peace, >Sarah Fox, >Chilly Columbus, OH > > >_______________________________________________ >pianotech list info: https://www.moypiano.com/resources/#archives > > Regards, Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T. mailto:pianotuna@accesscomm.ca http://us.geocities.com/drpt1948/ 3004 Grant Rd. REGINA, SK S4S 5G7 306-352-3620 or 1-888-29t-uner
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