Humidity Swings and Your Piano

I’ve briefly touched on this topic before in a previous post, but perhaps it is time to revisit how humidity affects the tuning of your piano.  This has been a hot topic in piano tuning circles lately on one of the technical lists that piano tuners from all over the world monitor.  Technicians like myself can post a particular question or problem they’re having and other technicians will suggest fixes or remedies.  The subject of humidity control around the piano has drawn more interest and heated responses that any subject I’ve seen in quite a while.  Some responses have contained minute details of how and why wood reacts to humidity changes………. it’s enough to make your eyes roll back in your head and put you to sleep.  It will suffice to say that there is no doubt that humidity swings contribute greatly to your piano going out of tune.

Since it is a given that humidity swings affect the tuning of your piano, the obvious counter to this effect is to control the environment around the piano.  To call on a familiar phrase, easier said than done!  I am of the opinion that if you are comfortable in your home, your piano will be comfortable.  Most pianos will change slightly from season to season, but since pianos should be tuned at least twice a year anyway, such seasonal changes can be corrected in the normal course of tuning and maintenance.  However, some pianos are affected more by humidity swings than others.  I have seen specific pianos change pitch from 30 to 40 cents between seasons.  (We divide half-steps into a  hundred parts and call them cents, so a 30 to 40 cent deviation from one season to the next means that the pitch has changed 30% to 40% of a half step)  In such extreme cases, I usually recommend the installation of a humidity control system directly on the piano.

These humidity control systems are manufactured by a company called Dampp Chaser.  They are two part systems that contain a de-humidifier element to remove excess moisture from around the piano, and a humidifier element to add moisture when the environment around the piano becomes too dry.  The system is controlled by a Humidistat, which measures the relative humidity in the piano and activates either the de-humidifier or the humidifier to keep the  environment around the piano within a specific humidity range, usually around 45%.  The Dampp Chaser systems work extremely well in pianos that are in small rooms or homes.  In institutional or church settings where pianos tend to live in rather large rooms or auditoriums, the addition of a piano cover can help limit the amount of space the Dampp Chaser system has to control, thereby making the system more effective.  The addition of such a system to a piano does not eliminate the need for regular tuning, but it definitely helps in minimizing the humidity related pitch swings.

I don’t always recommend these systems because the purchase and installation can be a bit expensive, but for sensitive pianos that tend to have major pitch changes when the seasons change, they can help greatly in preserving and extending the useful life of an instrument.  If you’d like more information on this subject, or anything else piano related, please contact me.

Thanks for tuning in!

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