tech@steinway.com wrote: > > In our opinion, if the room can be succesfully kept within the range of 40 to 55 % relative humidity, a Dampchaser is not necessary. > > Steinway and Sons suggests the use of the Dampchaser when the location can not be controlled within these ranges. > > Mike Mohr > Steinway factory, NYC At 09:57 AM 11/9/97 -0500, you wrote: > >Hi: > > > >I hope the subscribers of this list don't mind a question from somebody who is not a tuner or technician. > > > >I own two Steinway grands: a model D less than a year old, and a model B about two years old. My question relates to the necessity of using a Dampp Chaser system. > > > >On the model D, the dealer installed a Dampp Chaser system and it has always concerned me that the long rods are very hot -- you can't even touch them for more than a few seconds. > > > >I brought this to the attention of the dealer's technician and he moved them down a couple inches (thereby adding more holes to the piano woodwork!). > > > >But still they remain very hot. > > > >On the other hand, the Dampp Chaser wants a drink every week! So it seems that the system is fighting itself. > > > >The final straw is that I just bought a couple hand-held hygrometers (I got two different ones to, hopefully, make sure they were in the ballpark with their humidity readings). In the room with the model D, the humidity is consistently between 40% and 50%, which sounds good. > > > >In a nutshell, is a Dampp chaser necessary in my scenario, and does it appear to be malfunctioning since it is always very hot to the touch, yet wants to be filled with water each week? > > > >Thanks very much for your comments. > > > >Frank Leister > >Mechanicsburg, PA > > Dear Frank, Let me explain the operation of the Dampp-Chaser humidity control system so that you can decide for yourself whether or not you need it. The humidistat installed with the system regulates the operation of the humidifier and the dehumidifier(s). The system is designed so that one of these components is on all the time. Either the humidifier will be on or the dehumidifier(s) will be on. There will never be a time when both are on at the same time. Likewise, there will never be a time when neither one is on. For example, the system will dehumidify until the humidistat senses that the humidity level has dropped to 40% RH. At that point the dehumidifier turns off and the humidifier turns on. It stays on until 47% RH is reached, and then it is turned off and the dehumidifier comes on again. The system cycles between 40% RH and 47% RH and is quite effective at maintaining a stable moisture content in the soundboard and in the other piano parts. Now the humidistat calibration points I've used in this example (40% and 47%) are not sacrosanct. One humidistat may have calibration points of 42% RH and 50% RH. Those of another humidistat may be 38% RH and 44% RH. 50% RH and 38% RH are the high and low limits of the thousands of humidistats we make each year. The maximum differential allowed is 9% RH. The point I am getting to here is the exact humidity limits are not terribly important so long as they are between 38% RH and 50% RH and they are consistent day after day, month after month. In order for the dehumidifier(s) to be effective, heat has to be generated. The dehumidifier you describe is probably a 50 watt unit. It is hot to the touch. It is 130 degrees Fahrenheit with a reasonable flow of air moving around it. It is slightly hotter with a poor air flow. I don't think I have ever heard of an installation with poor air flow so I suspect you are feeling something that is about 130 degrees. The fact that the dehumidifier(s) are hot and the humidifier is requiring water simply says that the system is cycling. This is good. It will continue to do this until the ambient humidity level either goes way up or way down, and the humidifier or dehumidifier(s) run out of capability to change the humidistat. At this point the humidifier or dehumidifier(s) remain on full time. The system won't cycle until the ambient level changes enough to put the humidity level within the capability of the humidifier or dehumidifier(s). Our quest with new products and modifications to old products is to increase the humidification and dehumidification capability so that the moisture content remains absolutely constant, irrespective of how high or how low the humidity goes. One of our very new systems for a vertical piano will maintain essentially the same soundboard moisture content regardless how high or low the ambient humidity gets. We are close to doing the same for a grand piano. A great deal of time goes into research at Dampp-Chaser. Please don't misinterpret the above. All of our humidity control systems reduce moisture content changes significantly. The most recent developments provide an even greater reduction in moisture content changes. I am emailing you three performance graphs that show soundboard moisture content results at low and high humidity levels with several different systems. They are self explanatory. (The Dampp-Chaser performance graphs are too large to post. They are available to anyone who is interested. Email a request to us at piano@dampp-chaser.com and we will forward them to you as .gif files.) The last point I would like to address is the 40% RH to 50% RH maintained in the room in which the Steinway D is located. This is a great humidity level. If this is an inside room and you are truly maintaining this year round, then I would be the first to say you don't need a piano humidity control system. Please note the caveat about this being an inside room. This is important because if you are maintaining this in a room with an outside wall, you are subjecting that wall to condensation within the wall structure and subsequent deterioration. Each one of the humidifier manufacturers in the United States provides a warning to this effect somewhere on their product. The following are selected sections from April Aire and Sears publications which are typical of these warnings. April Aire - "While some humidity conditions may be ideal for comfort, they are, in many cases, less ideal for other reasons. An indoor relative humidity of 60% may fulfill all the requirements for comfort, but it can result in damage to walls, to furnishings, etc. The fogging of windows is usually an indication of too high relative humidity, and it must be remembered that this same condensation is taking place inside walls and other places vulnerable to damage by excessive moisture. It is therefore necessary to set safe limits of indoor relative humidity levels to receive the maximum benefits from correct humidity, without making the structure itself susceptible to damage. It is recommended that Temperature Humidity Table II be followed to insure these benefits." Table II Outside Temperature (degrees F) Recommended RH +40 45% +30 40% +20 35% +10 30% 0 25% -10 20% -20 15% Sears - "In order to determine the safe relative humidity for homes exposed to various low outside temperatures, the National Environmental Systems Contractors Association conducted tests and published recommended humidity levels for various outdoor temperatures. These are shown in the chart (same chart as Chart II, above). These levels help prevent damage to your home such as water running down the walls or even building up inside the walls." Research Products Corporation, the parent company of April Aire, devotes two pages to this in their very excellent 12-page booklet, The Story of Humidity. Now how do I square this position with that of Mike Mohr? Mike provides the caveat "if the room can be successfully kept within the range of 40 to 55% relative humidity, a Dampp-Chaser is not necessary". The operative word is successfully. I would not try keeping a house in Mechanicsburg, PA at these levels during the kind of winter you folks get up north. Bob Mair Dampp-Chaser Electronics Corp. Hendersonville NC damppchasr@brinet.com > > >Dear Frank, > > > > > >Scientific study carried out at the CAL Lab at the Smithsonian Institution has measured the effects of temperature and relative humidity on furniture. There findings have established that a range of RH between 40% and 60% should be maintained, and that it is most important to keep the RH constant, even if it is slightly above or below the recommended levels. > > > > > >Personally, I follow the advise that it is better to control the room RH, and that you should be more concerned about too little moisture, than too much. > > > > > >I have not seen any independent scientific testing that proves the Damp Chasers actually control the moisture content of the wood in pianos. I invite anyone with evidence to present it. > > > > > >Ken Eschete, RPT > > >Professional Associate - American Institute of > > >Conservators (AIC) > > >keschete@bellsouth.com Dear Ken, I'm not as young as I once was and my memory is not as good, so please excuse my failure with names and other details. In 1987 and 1988, Dampp-Chaser spent a sizable number of hours developing a humidity control system for museum cases. This was a reasonably sophisticated unit with the condensation produced through a thermo electric module. We developed a pretty decent unit and then did market research. This procedure may seem backwards, but not so much as one might expect. At any rate I came away from discussions with conservators at a number of institutions, including the Richmond (VA) Museum of Art and the Washington Museum of Natural History, with the conclusion that their space requirements were too limiting and there was too little money available. At this point we gave up on this product as having very limited commercial potential. I relate this to give you some background. During the period of this activity I attended two conventions, one in New Orleans, the other Cincinnati. I believe they were both American Institute of Conservators conventions. A paper was presented at the one in Cincinnati by a highly respected conservator. It dealt with humidity control within museums, and I truly wish I could remember more of the details, but one of the things that really stood out about that convention was his description of very poor humidity control in a private museum in Boston. A significant part of the museum was glass walled. His slides showed considerable condensation on these glass walls with the point being that a different philosophy toward humidity control would have to come forth if the building that housed this museum was going to last. Now I can't begin to remember the specific humidity levels described, but I can develop them easily and say that in Boston with temperature levels dropping to the teens and in some cases less, any RH level above 30% is going to cause problems. Your answer to Frank Leister states that you follow the advice that it is better to control the room and that the Smithsonian study says that the best level is 40% to 60%. By inference, you would control the room environment to 40% to 60%. I suggest that this is not a good practice where the outside temperature stays below 30 degrees Fahrenheit for any significant period of time. Please review the information I supplied to Frank (above) relative to that supplied by furnace humidifier manufacturers. This might be helpful. I've also emailed you performance graphs which show the effectiveness of various Dampp-Chaser piano humidity control systems. These show soundboard moisture content at 72% RH and 20% RH for two situations. One is without humidity control; the other shows protection with various Dampp-Chaser systems. These graphs are for our internal use. We use this information for direction, so that we can know when we have made an improvement. We don't generally promote the product through use of these graphs, but I certainly don't mind using them to pass information along. In response to your comment about independent scientific testing, this is scheduled shortly after the first of the year with Professor M. W. Kelly, School of Forest Resources, North Carolina State University. Bob Mair, Engineer Dampp-Chaser Electronics Corp. Hendersonville NC damppchasr@brinet.com
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