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Prior to my 2018 move to Phoenix, I had spent all of my professional life in one river town or the other, and the question everyone seemed to want answered is how to better control the humidity surrounding a piano.  Is it better to install a humidity control system underneath the piano?  Is a whole-home system worth the expense?  What about room humidifiers?  Everywhere I went, I found myself answering this question.

Interestingly enough, however, my experiences in Phoenix (and the time I’ve spent with a number of local technicians, furniture store owners and performance venues) have changed my answer dramatically.  With that in mind, I thought it was time to revisit the idea of humidity control around a piano and address the specific scenario of caring for your piano in the Sonoran Desert.

piano frames made of woodMost decent pianos are built from a combination of metals and organic materials.  Wood makes up around 85% of the organic materials and, thus, pianos tend to be very susceptible to changes in temperature and humidity.  …but this is where things can get confusing.  On average, wood gains or loses about one percent of its moisture content for every five percent change in relative humidity (Relative humidity is the ratio of actual moisture currently in the air vs. the amount of moisture air will hold at a given temperature).  When relative humidity rises significantly, the piano’s wood components will expand – causing (among other things) the piano to push itself out of tune and action parts to swell or stick.  When relative humidity falls, the piano’s wood components contract.  This relaxes string tension and causes the piano to fall out of tune.  As the thinnest and most sensitive wooden part of a piano’s construction, the soundboard is especially vulnerable to damage from these changes.  It’s also a very costly part to fix or replace.  This is why many in the piano industry are quick to recommend humidity control systems for the piano.

I can see why they might be worried.  However, while most major piano companies recognize the benefits of humidity control systems in cases of extreme fluctuations in relative humidity, none advocate the inclusion of a humidity control system on every piano they make (That is why they don’t build them into their pianos at the factory.).

relative humidity graphic

Warmer air can hold more water. If the amount of water in the air rises with the air’s temperature, the ratio remains the same – thus, the relative humidity is unchanged.

Wood doesn’t always take on moisture or release moisture when the humidity rises and falls.  As the temperature increases, air is capable of holding more moisture.  Thus, if the temperature AND humidity go up at the same time, wood won’t swell.  Also… if the temperature and humidity FALL at the same time, wood won’t shrink.  The only time pianos start to struggle is when the temperature goes up and the humidity doesn’t… or when the temperature stays the same, but the humidity rises or falls.  It’s the RATIO between them (the relative humidity) that can cause damage to a piano or fine piece of furniture.

Inside your (climate-controlled) home, however, things are very different.  If you live in the Sonoran Desert, your home is probably air-conditioned.  Thus, the amount of moisture that the air can hold is limited both by the temperature of the air and by the air conditioner itself.  This means the spaces inside your home experience very little temperature variation.  Add to this the fact that Phoenix experiences an average relative humidity of 37% (just a couple of percentage points beneath the 40% ideal) and you can see why most pianos do very well here.  In general, Phoenix-area homes tend to have a very stable relative humidity.

So.  Should you put a humidifier system on your piano in the Sonoran Desert?  In a word… no.

I have spoken with technical representatives from every major piano brand and they all make the following suggestions:

  • Keep the temperature in your home as constant as possible (varying by 5-10 degrees maximum). This is especially important during the summer.  You can raise the thermostat from 75 to 80 to lower your electric bills, but – for your piano’s sake – keep your AC unit ON during the hot months.  Likewise, use the furnace to keep your home comfortable during the winter.  The more consistent the temperature, the better for your piano.
  • To prevent excessive dryness, use appropriate window coverings (shades, blinds, etc.) and include some (regularly-watered) leafy plants in the piano room.
  • To prevent excessive moisture, avoid sudden dramatic temperature changes and keep windows closed during cloudy or rainy days.  Never place your piano near an active fireplace, heat vent or “hot” window.

“What’s the big deal?” you ask?  Why not just install them on every piano and be done with it?  Steinway’s Technical Director, Kent Webb, said it best:  “Installing a humidity control system on a piano that doesn’t need one is like giving a patient medicine when he’s perfectly healthy.  You can create a problem where one doesn’t exist.”  By “over-controlling” the humidity around your piano, you can cause the very soundboard damage, pin-block cracks, rust and tuning trouble you’re trying to prevent.  You can also waste a ton of time and money trying to maintain humidifiers when the humidity they produce is immediately whisked away every time your home AC system starts circulating the air.

humidity control system upright piano

Most systems like this one – if necessary and properly maintained – will provide some protection for the soundboard, but will do little to improve the piano’s tuning stability or action function.

Why, then, do so many local piano industry professionals recommend you install a humidity control system onto your piano?  Some recommend them simply as an income source.  They make good money selling and installing the systems (which can cost up to $750) and then coming back to replace pads or correct problems that come from improper system maintenance (a common problem with these units).  Some simply don’t understand relative humidity and think – when the humidity rises or falls – the piano must be suffering.  …and some simply recommend them because they were trained to (usually by someone who doesn’t live in a state that ranks 49 out of 50 in relative humidity).  You just never know.

Don’t get me wrong.  In some areas (like my old river towns), humidity control systems can be life-savers.  In the Sonoran Desert?  They are a waste of time and money.  Don’t let someone scare you into spending hundreds of dollars on a useless piece of equipment.  Make an informed decision about humidity control for your piano or contact someone at Riverton Piano Company and we’ll help you decide what to do.   It’s not about the money – it’s about your piano’s long-term well-being.