The volume of air in my living/dining area is large, and I have pretty good weather sealing around the large patio doors. This means that the piano is safe from the high RH outside the flat. Even opening and closing the front door to enter or leave the flat does not change the RH much at all.
I do have a RH control problem all the same — the RH swings a lot — from around 38% when the aircon is turned on for an hour at 26°C (outside temperature about 30-31°C ), to about 65% when the aircon has been left off for a few hours. As the RH goes through its gyrations the tuning on the piano also drifts. Not so much now that I’ve learned to set the pins and strings better when I tune the piano, but still enough that it bothers me. Now I think I have found a way to keep the RH around 60% and limit the swings to about ±5% around that mark — the Sharp KC-850E humidifying air purifier.
I was actually looking for an air purifier with HEPA filter to reduce the cat dander at home. I have a mild allergy to cat dander, and have a chronic low level allergic rhinits. A friend who visits often has an even stronger reaction. After about 5 minutes in the flat he starts to tear, sneeze, and get a runny nose and blocked sinuses.
The humidifying air purifiers from Sharp attempt to keep the RH at around 60%. Of course, they are intended for use in low RH climates and in air-conditioned spaces. They can also be used without the humidifying function by leaving the water tank empty.
With the KC-850E running (its very quiet!) I get cleaner air, and RH swings between about 55% and 65%. I also got the smaller KC-840E for my home office because it adjoins the living/dining area, and the KC-850E alone can’t handle that big of a space. They aren’t that cheap but these things last for years. And they are on sale now (in Singapore) until 31st July 2009.