A couple thoughts beyond what I posted earlier. Heat is conveyed (the physicist types tell us) in three ways: radiant, conduction (might be the wrong term) and convection. With forced air heat, we are mostly dealing with convection, and the variant is whether and how much the air is moving. This affects how much the object (piano) is heated or cooled by the air that is a different temperature. And mostly we don't worry too much about it, and worry more about how dry the air is, and the movement of water to and from the wood of the piano. But if there is a heat source like a radiant heated floor, or an old fashioned radiator, or baseboard heat (and any number of other possibilities), there is the possibility that the "body and material of the piano" become heated more than the ambient air. I think this happens with my example of the console on a brick, radiant heated floor. I think it also happens with a couple of grands I service that are next to baseboard heat (the type that has hot water flowing through long, low profile radiators). I have one with a full system and undercover, another with a double tank. Both have horrible tuning instability. It is better than it was without the systems, but as bad as what I see in "normal" houses without a system. (And, yes, I have discussed placement of the pianos with the customers, and, frankly, there is just no good option). I think that this proximity to heat source causes the whole structure of the piano to become a fair amount hotter than the air, and so the moisture just leaves it much faster than the system can replenish: there is an active "moisture subtraction" system in effect, with more power than the active moisture addition system. I'm thinking I need to come up with some kind of baffle/insulator system for these pianos. Problem is, it has to look acceptable (I'm real good at the kind of thing that doesn't have to look so good <G>). I'm thinking in terms of "space blanket" type design, with metal foil and insulating layers sandwiched together. But so far it is just idle thinking while tuning those pianos. Regards, Fred Sturm University of New Mexico fssturm at unm.edu On Mar 26, 2008, at 11:07 AM, Fred Sturm wrote: > I think radiant heating is a real challenge. I have a console on a > brick, radiant heated floor, that has crazy swings in spite of well- > serviced dampchaser system and back cover. (Over time, I up-graded > to DRY humidistat, then back cover. Each step helped some, but not > as much as expected. Still unacceptable). > I think the addition of heat by conduction, due to the piano being > in contact with the hot floor, is a big part of this. I have been > puzzling about how to deal with it. My best guess so far is some > kind of insulation - don't know how much good caster cups might do, > whether to do some kind of blanket under the bottom board. > Definitely an issue that needs to be examined and solutions > proposed and experimented with. I wonder whether the contact of the > grand's legs with the floor isn't part of the problem, in addition > to what is radiated up from the floor. Rubber casters might help - > probably not, but perhaps worth a try as part of a solution. I'm > thinking about the conduction part of the equation, which might or > might not be significant in this case. > Regards, > Fred Sturm > University of New Mexico > fssturm at unm.edu > > > > On Mar 26, 2008, at 7:46 AM, Joel A. Jones wrote: > >> Jon, >> >> I have a similar situation in that the heat is radiant in the >> floor. >> The church added a long piece which wraps under the piano, >> thus keeping the temp and humidity even inside the piano. >> >> With your floor length cover I would explore adding a few straps >> with velcro to pull the extra length of cover underneath the >> piano. My guess is that this would even out the temp and >> humidity and eliminate the sauna effect you are experiencing >> now. >> >> Let us know how you handle this situation. I am very >> interested on what happens. >> >> Joe >> Joel Jones, RPT >> Madison, WIl >> On Mar 26, 2008, at 7:51 AM, Jon Page wrote: >> >>> I recently took over the tuning for a church with a 7' Imp. >>> Bosendorfer. >>> >>> On my first visit the music director asked me to remove the tank. >>> I lifted a section of the full-length cover and got under the piano; >>> it was quite warm and humid, too much. >>> >>> This is an old church with wooden floors with the parish hall below. >>> The heat radiated up through the floor and was trapped within the >>> cover causing the piano to become even warmer. With the humidifier >>> running it was like a sauna or greenhouse (to a degree). >>> >>> Of course, as I was tuning, the piano drifted since it is now being >>> acclimated to the room. That was fun. >>> >>> I recommended that they ditch the full length cover and supplement >>> the rods with a string cover. This way the string cover can remain >>> on >>> during services and removed for performances if needed. I don't >>> think >>> they need the H20 since there's no excessive heat or cold in the >>> winter >>> and no one willing to monitor it. >>> >>> I suggested they place a hygrometer inside to monitor the piano when >>> first opened and after service and to ascertain the effect of the >>> full cover >>> and whether they really needed the H20 in the winter. >>> They have yet to do that. >>> >>> The music committee asked the dealer about the full cover and DC >>> and the dealer naturally stuck by their sale. I was asked by the >>> music >>> director to give my suggestion at a committee meeting next week. >>> >>> So my question is, with the heat radiating upwards from the hall >>> below >>> is a full cover ideal. I believe a string cover and heat rods are >>> sufficient. >>> I can see where a full-length cover in an auditorium can be useful >>> but in this case I think it is detrimental. >>> >>> They don't really need the bulky, protective cover because there >>> is no traffic around the piano. A lighter cover would do if >>> desired. >>> -- >>> >>> Regards, >>> >>> Jon Page >>> >> >
This PTG archive page provided courtesy of Moy Piano Service, LLC