Dear Ken; You wrote on Fri, 15 Dec 1995 06:11:03 -0700 (MST), asking a few questions about the effectiveness of "Damppchasers" (i.e. Dampp-Chaser humidity control systems" on tuning stability. Since responses questioned your use of the term "Damppchasers", whether you meant you had installed just a dehumidifying rod or a complete system, I called and we talked on the phone. Since others might be interested in that discussion, I will relate the essence of it here. I am also sure that future responses to my comments will also help me learn more, too. I have been installing Dampp-Chaser humidity control systems in pianos for over 15 years. While others have installed many more systems than I, I think the 300+ systems I have installed and monitored - some for as long as 14 years - has given me some small amount of experience. A system, to me, includes at least five parts; either their 5PS (five-part system for vertical pianos) or 5GPS (five-part system for grand pianos). This includes the humidifier, dehumidifier, humidistat, low water warning light and water fill kit. When we talked, I was pleased to hear you say that you would never install a dehumidifying rod all by itself without a humidistat to control it, and that you also always install complete systems. A knowledgeable piano technician would (probably) never (and, at least, very rarely) install a dehumidifying rod by itself, without it being plugged into a humidistat, any more than a knowledgeable heating system installer would install a heating system in a house without having a thermostat on it. Just as the thermostat turns the heater on and off when it is needed, the humidistat turns the dehumidifying rod, and the humidifier, if there is one, on and off when it is needed. (There are, of course, acceptions to every rule. There are areas of the world, such as the Amazon Rain Forest, where the humidity is never below 80% or so, and the rod would run all the time anyway - in theory. The same is true for Olympic Rain Forest in northwest Washington state. In vertical pianos, the dehumidifying rod can be expected to dispell approximately 1% R.H. for each watt; a 25 watt rod dispells 25% R.H. If the high humidity is, say, 92%, a 50 watt rod would lower that to 42%, if let run continuously. But, since most pianos are where people live, and people tend to turn on the heater every now and then, and heaters tend to dry out the air . . . I would always install a humidistat. And besides, tend to take their pianos with them when they move - and the new climate is usually different than the old one. When someone moves from Hawaii to dry Central Oregon, for example. The dehumidifying rods that were installed were appropriate, there, are going to overdry the piano now, since they were on all the time and our humidity here, both summer and winter, tends to be too low. So I would always install the rod with a humidistat to control it.) In particular, Ken, you mentioned living in Alberta, where the temperature reaches -30 in the winter. This, of course, means the heating system is on a lot and the air gets pretty dry - even if it were not already dry outside. Someone noted that they had seen systems where the dehumidifier rod was installed too close to the humidistat, and therefore turned the dehumidifying action off too quickly - which would mean the humidifier would run longer, and tend to bring the humidity at the higher end of its 42% R.H. plus or minus 5%. (And by the way, the plus and minus rating is Dampp-Chaser's statement. Our own tests, in pianos, in homes and churches, with recording hygrometers, tells us that over a week or two or constant recording, plus or minus 1.5-2% is the norm, and sometimes plus or minus 3%. In other words, we have tested and monitored a number of systems, and they are more accurate, by about twice, than what D-C claims. Just thought you might like to know that.) While Dampp-Chaser recommends that in a "standard" installation the humidistat be mounted 6" from the humidifier, we sometimes alter its position on purpose, especially if we live in a very dry region, as I do - so the ones mentioned by other technicians as being "wrong" may have been done by someone who knew what they were doing, and modified its placement to get the best possible action for that particular piano. More often than not, unfortunately, the ones we see like this were simply installed by someone who did not know what they were doing, and either did not read, or did not understand, the printed and photograph directions. Recently, Dampp-Chaser came out with two different models of humidistat, to account for pianos living in drier-than-normal or more-humid-than-normal climates. Check their informational for more information there. (You can call them at 800-438-1524, and ask for their complete informational kit. They will send it at no charge to piano technicians.) But, regarding the three year old Yamaha G2 you service in a church. I asked on the phone whether you tighten the plate bolts on every piano before tuning it, and you said you did not. That sparked a discussion of reasons to tighten the plate, pinblock and rim bolts, tools we use, and results. Reasons for tightening the plate, pinblock and rim bolts: I have been tightening plate bolts before tuning, on virtually every piano I tune (I miss one a month, maybe, if I get distracted by the owner while setting up), for over 15 years. I have found that with a very few exceptions, most all pianos have loose plate bolts most every time I tune them. On Steinways, whether verticals or grands, old or new, I can seldom get even one out of ten plate screws to turn. But they are the exception, rather than the rule. On most new pianos I tune, most screws will turn 1/16-1/8 turn the first time I tune the piano. A little less after that, and as time goes on, with tightening once or twice a year during regular tunings for several years, we get to a place where everything is really, really tight, and they won't even "snug" any when I attempt to tighten. A "snug", to me, means it might move something on the order of 1/64 of a turn - i.e. almost not at all. When tuning vertical pianos, I always tighten all visible top end (i.e. accessable with the front open for normal tuning) plate and pinblock bolts. I do not normally tighten those under strings, whether in the pinblock area or speaking length, but if the others were all real loose when I began, I might do these also. (I include tightening the pinblock and plate bolts as part of my regular tuning service, but usually charge extra if I have to loosen strings and move them out of the way to get to hidden secrews, because it takes so much extra time.) When tuning grands, I tighten all accessible plate, pinblock and rim bolts (except Baldwin grands with Accu-Just hitch pins, for the obvious reason). Why do I do it? I started doing it because two manufacturers, Kimball and Yamaha, recommended it. I continued doing it because, well, see Results, below. Tools we use: We had a discussion of tools Ken was using, and those I was using. I use a "plate screwdriver", either slotted or Phillips, which are available from Pacific (where I got mine), Schaff or American. These are about 6" long, and the top has been ground to fit in a standard tuning tip. The reason I use this, instead of a ratchet, as some do, is because I don't want the extra weight of a ratchet in the tool kit I carry into every house! If you are going to do this on every piano, every time you tune it, then you need to have it in your #1 tool kit - and I am not going to carry around a ratchet set in my tuning kit. Use care, because the purpose is to snug up the bolt/screw, not to tear it out of the piano. For bolts, such as the four or five at the top of many old uprights, and the rim bolts on many grands, including Steinways, I use a 6" Crescent wrench. Schimmel grands have Allen head bolts, so I carry that tool in my van, and only take it in to the client's house when needed. Results: One of the first serious examples to prove the value of this service was tuning a G1 on a dealer's floor many years ago. In fact, about 1981 or so. I had tuned the piano (which I had tuned twice a year for the couple years prior, and was traded in by my client on a C3) a week earlier, and did not feel it was holding pitch very well. I checked the pitch (with a PT-4, I think), then got the idea to tighten the plate and rim bolts, checking pitch again - and found I had raised the pitch of the piano about 4 cents by tightening the plate screws! Lights went on in my head. A few years later, while tuning for a nationally-known duo, whom I knew from working together on prior tours, I was preparing to service their two nine-footers. I asked if there was anything in particular the pianos needed, as I always do, and they said they were thinking of getting new pianos; in the ten days of playing these two, neither of them had held a decent tuning even to the intermission, and they were very disappointed. They told me where they had played, who had tuned for them, and I knew I had been preceeded by very, experienced, competent tuners. The fact that each location had a different climate should not have affected these $60,000 plus instruments to the extent of justifying their complaints. I sent them off to dinner and we agreed to talk in three hours when they returned, ready to play. I kid you not - virtually every pinblock, plate and rim screw took at least a 1/16 turn, many more than an 1/8! I was shocked. Further, one of these was a brand new piano, recently out of the crate prior to this tour, and the other three years old. Both had screws equally loose as the others - telling me that in three years, virtually no one had ever tightened the screws! And the new one, apparently, arrived, got all its set-up and prep, without anyone tightening the screws! And further, none of the ten previous tuners, on the ten preceeding days, tightened the screws. After the concert, they told me they were very impressed, the pianos were both great, they held their tunings . . . and wondered why I was so great. I informed them that, in the future, whenever they get any new pianos, whether "new" or not, they should insist the pinblock, plate and rim bolts be tightened every night, before every concert. (Yes, I checked the pianos, too. Only a few unisons were slightly out in the whole piano. And no, I do not believe I am any better tuner than most of the ten who preceeded me - I just remembered to tighten the plate bolts, and they did not.) Your mention of the humidity (about 29%), and the piano's dropping pitch so much, 8-10 cents each month in the winter, is not unrealistic for a piano that has no humidity control installed. However, since yours did, I suspect, as I said on the phone, the plate bolts need tightening - and - possibly the pinblock is not bedded to the front of the plate flange. If the pinblock is not bedded to the front of the plate flange, having tight pinblock, plate and rim bolts will help a great deal, as will a properly installed humidity control system. (Dampp-Chaser makes the only one suitable for pianos, by the way. Room humidifiers, as you know, not only do not control the humidity very well. And one of Newton's laws says that all things, including this humidity, will take the path of least resistance - meaning it will go into the sofa, carpet and masonite wallboard before it will go into a hard rock maple or beech pinblock! And, to top that off, since those produce cold air humidity, which looks for something cold to condense on, like the cold part of a glass of ice water, it is much more like to simply go to the piano's strings and plate and cause rust!) So, I think you skepticism about the usefulness of the system will be dispelled when you are sure the piano is properly screwed together, and the pinblock is properly bedded. (And from my experience, Yamaha usually does a pretty good job of bedding their pinblocks. However, Murphisan lives in Japan, too . . . ) And finally, someone said the grand piano cover needs to extend all the way to the floor. Maybe it does, I cannot say for sure. But I do know that the value of the warm air humidity produced by the Dampp-Chaser system is because warm air goes up, and this takes the humidity up the soundboard, spreading it out under the piano and allowing it to enter the skeleton, including posts, rim, belly rail and, through osmosis, into the action and pinblock. (Yes, I have done torque tests, and while installing a system in a vertical with tuning pins too loose to tune has, in over 50 cases, restored the piano to tuneable condition in one to three months, every time - it is not as dramatic in grands. It usually helps some with loose tuning pins, but not a lot. More in the 5-15 pounds, whereas in a vertical pinblock torque can be increased by as much as 40 pounds!) But back to the grand cover length: If I understood Physical Science 101 (and I may not have, you understand), but IF I did - then once that warm, moist air, got cold, and got heavy, and fell down below the bottom level of the rim, it is no longer going to do any good for the piano. Yes, if it remains in the enclosed area below the piano it could do something; but I suspect what it would most likely do is aid the formation of rust and corrosion on the trapwork, lyre rods, inner lyre works and casters and gauntlets! True, there is certainly a value in keeping any heater vents that might be near from blowing dry, hot air up there. But in most churches I know, they run the heating system very little during the week, and I don't know that I would recommend buttoning all that humidity up seven days a week on that account. Certainly there is room for various options here, depending on the individual situation, and I am sure there are times when a floor length cover is desirable. There are also times when a water-proof cover are desirable, but I would not want waterproof to the floor, for the reasons I mentioned. As I said at the beginning, one of the reasons I am responding in writing is because I am sure someone else knows something I don't, and will respond with something that will help me grow my understanding as well. Randy Potter, R.P.T.
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