Besides tuning your piano on a regular schedule, the best way to improve tuning stability is to reduce the changes in humidity that occur in most homes. Using an air conditioner in humid summer months and adding a humidifier to your central heating system will reduce the extremes of high and low humidity and improve tuning stability. However systems designed to be installed inside of pianos will control humidity-related disorders still further. Installing a humidifier/de-humidifier system inside the piano keeps a humidity level of approximately 42% relative humidity. In new instruments, this helps keep moisture in the wooden parts of the instrument. The soundboard flexes through moisture gain and loss, pushing against the bridges and strings, driving the instrument out of tune. By controlling the humidity level around the soundboard, the system promotes tuning stability during seasonal humidity changes. 

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