A piano needs to be tuned regularly, especially since the changing seasons will affect the tuning. In the Netherlands, the relative humidity can go as high as 80% in summertime and fall back to 30% in winter (which is too dry for your piano). The wooden parts of the instrument respond to humidity, expanding or shrinking. These changes lead to fluctuations in the instrument itself. Moreover, when your heat is turned all the way up as the winter cold sets in, your piano is likely to go out of tune faster. Finally, if you play your piano frequently, that can also influence the tuning.
To keep your instrument at the right pitch and to maintain optimal sound, it’s generally recommended to have your piano tuned twice a year.
Changing humidity is the most likely culprit if your piano is out of tune. A hygrometer can be used to measure the relative humidity. Where your piano is concerned, the more stable the environment, the better. A piano in a room that maintains a constant climate will probably stay in tune for longer than a piano in a drafty room positioned near the door. If your house is on a street corner, you should ideally put the piano against an inner wall to maintain a more stable temperature.
What I sometimes encounter is a vase or bucket of water placed inside the piano with a cloth or old newspaper in it. This may seem like a nice solution to help your piano make it through the dry winter months, but I cannot recommend it. Too much moisture is never good for a piano – and a vase that could topple easily is very risky. Too much moisture can also cause rust to form on the strings.
If your home is too dry, a better solution is a humidifier to keep the entire room at the right level. Alternatively, you could opt for a Hydroceel unit, which is a tube that is placed in the piano which evaporates moisture evenly.
Another possibility is a Piano Life Saver system: an electronic system that includes a humidifier and a dehumidifier, thus achieving a stable humidity balance inside your piano.
Note: Just because these options are available does not mean that you are required to use one of the above systems. Each environment is different and not every instrument responds the same to humidity and temperature changes. I can give you appropriate advice for every situation.
Would you like to know more? Please feel free to contact me.