Humidity Control
Humidity Explained
If you tune in summer the bass sounds sharp in winter.
If you tune in winter the bass sounds flat in summer.
The reality is the bass section does not move much the treble section shifts sharp or flat which contrasts against the bass.
Why
Wood shrinks and swells with humidity changes.
The pitch of the piano plain wire increases with humidity and decreases when it is dry.
The further away from 45% humidity the more drastic the effect on the tuning at the opposite time of the year.
The closer to 45% humidity when you tune the better.
It is not uncommon to have pianos do a 1/4 to 1/2 step swing sharp or flat when the humidity changes either direction.
The soundboard manufactures build the piano with a curve in the soundboard intended to be its best at 40-50% humidity. Unfortunately in MN and WI that level of humidity is rare and as a result most pianos spend their usable life in an untuned state.
Soundboards have three states.
Most people see a piano. Believe it or not, there are three instruments in one because the soundboard changes shape with all the seasons.
What happens in winter?
The dry condition, moisture leaves the soundboard and the instrument becomes flat, the bass section and octaves do not sound right as the midrange pitch has fallen below the bass. It is not uncommon for the first snow of the season to arrive and for about a week the piano sounds ok, but once the moisture content of the soundboard shifts, the tuning shifts and (almost) overnight the moisture content changes from 40% humidity to 15% humidity. The colder it is outside the quicker the shift the the dry condition.
What happens in summer?
The humid condition, the soundboard absorbs moisture and the midrange pitch rises above the bass once again the bass octaves vs the midrange sound funny. The bass seems flat but the pitch the piano is now drifted sharp.....
How about spring or fall?
The soundboard is anywhere in-between the winter condition and the summer position. When you tune, the closer to 45% humidity the better. The further away from 45% humidity the more drastic the effect at the opposite time of the year.
Ironically this is one of the best times to tune an instrument but most pianos are sounding ok to the owners so they decide to wait.
The dryer it gets inside the more problems you are likely to have. When we hit a -20 below zero the HVAC system works hard to keep the space warm, it dries out the piano, the soundboard changes shape and individual tuning pins can become loose.
IF you are shocking yourself the environment is too dry for the piano.
If you tune in winter the bass sounds flat in summer.
The reality is the bass section does not move much the treble section shifts sharp or flat which contrasts against the bass.
Why
Wood shrinks and swells with humidity changes.
The pitch of the piano plain wire increases with humidity and decreases when it is dry.
The further away from 45% humidity the more drastic the effect on the tuning at the opposite time of the year.
The closer to 45% humidity when you tune the better.
It is not uncommon to have pianos do a 1/4 to 1/2 step swing sharp or flat when the humidity changes either direction.
The soundboard manufactures build the piano with a curve in the soundboard intended to be its best at 40-50% humidity. Unfortunately in MN and WI that level of humidity is rare and as a result most pianos spend their usable life in an untuned state.
Soundboards have three states.
Most people see a piano. Believe it or not, there are three instruments in one because the soundboard changes shape with all the seasons.
What happens in winter?
The dry condition, moisture leaves the soundboard and the instrument becomes flat, the bass section and octaves do not sound right as the midrange pitch has fallen below the bass. It is not uncommon for the first snow of the season to arrive and for about a week the piano sounds ok, but once the moisture content of the soundboard shifts, the tuning shifts and (almost) overnight the moisture content changes from 40% humidity to 15% humidity. The colder it is outside the quicker the shift the the dry condition.
What happens in summer?
The humid condition, the soundboard absorbs moisture and the midrange pitch rises above the bass once again the bass octaves vs the midrange sound funny. The bass seems flat but the pitch the piano is now drifted sharp.....
How about spring or fall?
The soundboard is anywhere in-between the winter condition and the summer position. When you tune, the closer to 45% humidity the better. The further away from 45% humidity the more drastic the effect at the opposite time of the year.
Ironically this is one of the best times to tune an instrument but most pianos are sounding ok to the owners so they decide to wait.
The dryer it gets inside the more problems you are likely to have. When we hit a -20 below zero the HVAC system works hard to keep the space warm, it dries out the piano, the soundboard changes shape and individual tuning pins can become loose.
IF you are shocking yourself the environment is too dry for the piano.
A story about a piano owner
The effects of humidity are predictable to seasoned piano technicians. Once upon a time there were two excellent piano technicians in a city. Sally plans to tune it as often as her mother....once a year. Sally has a decent ear and has been part a choir for some time. When the first tuning happens, it was one of the summer months, Sally pays Charles who leaves a card in the piano. Six months later, when the furnace is turned on the tuning shifts and the bass sounds off. Sally finds Bill a highly regarded technician and has them tune it then six months latter the bass sounds terrible and Charles gets the request to come tune the piano. This seasonal humidity cycle of back and forth and piano tech swapping is due to the predictable humidity shifts. Over the course of the next 4 years the two piano techs have a slow game of tic-tac-toe on the back of the card in the piano. Sally finally had enough and had me install a humidity control system on her piano. Now she enjoys a stable piano and tunes once a year.
What can a piano owner do to limit the effects of humidity swings Be proactive - have a humidity control system installed in your piano.
There are systems that fit grand pianos and upright pianos.
Which system is selected is depends on what type and size of piano you have.
If you do not have a humidity control system tune every six months at the moderate times of the year, or when you'll be using the piano. Clients without the system tune twice a year aim for a summer tuning at 65% humidity and a winter tuning at 30% humidity.
Be reactive - tune when your piano sounds its worst.
Have constant humidity swings cause you and family to enjoy your piano less and eventually give up on it.
Change tuners because you believe you received a bad product because of the predictable humidity swing and tuning shifted.Humidity Fluctuations can and will cause damage its just a matter of time
Older pianos have gone through more humidity changes and develop cracks in the soundboard, have issues with the pin block that hold the tuning or bridges splitting or have keys that don't play because of wood parts failing from drying out.
Piano location is an important factor in tuning stability; Pianos placed on heating, AC vents, next to a radiator, pipes, on the other side of a wall to a dishwasher or chimney, in front of a window, exposed to sun shine will have more difficulty staying in tune. Pianos located on second floors or in apartments will cycle through more extreme humidity fluctuations than pianos on a first floor or in a basement.
How a humidity control system works
A humidity control system both humidifies and dehumidifies your piano works by maintaining a 45% humidity level.
It is controlled by an automatic humidistat which is like a thermostat but it operates only on humidity.
In summer when the humidity level is above 45% the humidistat senses it and calls for dehumidification. A dehumidifier rod in the piano removes moisture from the air. Keep it plugged in and it automatically does its job.
In winter below 45% the humidistat calls for humidity. The user adds water to the system through the fill tube, which goes into a humidifier reservoir and is wicked over humidifier pads that need to be changed once a year when the piano is tuned.
I have a humidifier on my furnace and run AC in the summer is that enough?Whole house Humidifiers and air conditioners work to maintain a desired temperature, regardless of the humidity level. Most air conditioners in a house are unable to reduce the humidity level to lower than 60% which is going to impact the piano.
It is difficult at -35 to have a house system capable of keeping up without frosting all of the windows over.
Occasionally the whole house humidifier system may fail and the piano drifting out of tune is the symptom.
The real test is if your whole house air conditioner and furnace are keeping the indoor humidity stable the pitch of your piano will not go sharp or flat with the weather changes.A special note about schools and churchesPublic buildings are required to have more airflow than in a residential house. The greater the airflow, the quicker humidity's effect takes place. In situations like this, for a grand piano an undercover may be recommended to enclose the moisture produced by the humidity system between the bottom of the piano and the bottom of the soundboard. Some times a dual tank humidifier system or an extra dehumidifier rod is needed to maintain the correct humidity level at the most extreme times of the year.Client Success Stories
These tuning records are from a church with a Yamaha C7 grand piano
Without humidity control they were tuning 5-8 times a year.
We installed a double tank dampp chaser system with an undercover.
Now they are tuning once a year and enjoy a stable instrument year round.
We are a certified humidity system installation specialist. Your system is installed correctly and comes with a limited 5 year warranty from the Dampp Chaser Corporation.
Ask if a humidity system is right for your piano.
System types and costs
Installed the upright humidity control system is $550 plus sales tax
Installed the grand single tank humidity control System is $650 plus sales tax
Be a steward and maintain the system
There is a light panel which indicates when the piano needs water. This is like a low gas light so if you would not want to run out of gas on 35W in a traffic jam, you need to stop and fill the system. Failing to add water when it is called for in winter leaves the piano in a state where as soon as the moisture content of the soundboard changes your present tuning can be lost. Generally clients notice the system light blinking after the wake up in the morning or when they return home.
If you take care of the system, it will take care of your piano.
Leave it plugged in year round
It dehumidifies automatically in summer and humidifies in winter.
If you unplug the system your entire piano is unprotected.
Once installed your piano will still need annual tunings and your piano technician will need to change the humidifier pads on the humidifier system.
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All Photos and graphs on this page are used with permission of the Dampp Chaser corporation.