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Hi all,
In all the discussions I've seen about humidity, I've only read vague references to "avoid wide RH swings" etc. But what is considered too high or too low?

My house varies between about 28% in the winter to 80% in the summer. If I use a de/humidifier near the piano (Yamaha C7), I can narrow that to about 35% to 70%.

I'm considering buying a Dampp Chaser, but I don't know if my humidity changes are considered "wide swings." I currently need my piano tuned about every 4 months, and obviously want the soundboard etc to survive...

Any thoughts?
Thanks!!

Thats a huge swing so a DC system or like would be advised by most techs. Like always it's best to control the room but not that easy. Many manufactures say anything from 40-60% but always try to keep swings to 5% .

I've never understood why or how a DC system would work. How can something so small control a very local climate near the piano within the greater climate of an entire room or house?

It controls the climate within the piano, not near it. It really does work very well, though keeping your house at least in the 40-60% RH range makes it easier for the DC to do its job.

+1

There is no invisible vapor barrier around the piano to control its climate. Any adjustments made there will quickly equalize with the greater space in which the piano resides.

A whole room system is better and a whole house system better still. Plus, they'll not only help the piano, but everything else too, like the people who live there! As added bonus, you don't have to mount anything on your piano.

Here in France, when my piano was new 8 years ago, I began experiencing humidity swings between 30% in the winter (underfloor central heating) to 75% in the summer. Naturally I too was concerned about this, especially as the detailed Sauter handbook supplied, recommended maintaining relative humidity between 45-60% for an ambient temp of approx 20deg C.
At the end of the first year I had a Dampp Chaser installed. The results were spectacular, ever since the relative humidity has been maintained between 57-60% (recorded within the piano by the built-in hygrometer).
I maintain the system myself always using distilled water + the recommended water treatment additive, and my handbook log shows the pads have been changed 5 times, in 2009/2011/2013/2015 & 2016.

The addition of a undercover increases the effectiveness of a DamppChaser system.

People who do not have DC systems installed are not in a position to judge its efficacy.

Ideally, a whole house AC system maintaining precisely 42% humidity 24 hours a day would be best. Second best is to condition the whole house as best as you can (allowing for diurnal temperature, and therefore, RH fluctuations) and add a DC system to more accurately maintain the piano. As an owner of a M&H BB who does his own tuning and regulation, I can tell you the piano is more stable with it than without it.

I've monitored the RH around and under my piano for two years. It is now equipped with the usual DC components and a custom controller. The data gathered speaks for itself and shows that the DC helps to keep the tuning more stable when RH varies a lot with the change of seasons. By also disciplining yourself to always close the lid after playing, you will help optimizing the DC efficiency.

In a way, it removes moisture from the belly system of the piano the same way a blow drier removes moisture from your hair. The heat greatly raises the air's capacity to hold moisture, effectively lowering its relative humidity. The convection current helps carry the moisture away.

I'm regularly mystified why anyone would not have a system. They are a real benefit in 99% of situations. In regards to "its best to control the whole room", that is simply terrible advice since it is not practical in the vast majority of situations. If you live in an area that gets sub freezing temperatures during the winter months you will do very expensive damage to your home trying to keep the humidity up to 40% .

I've used humidifiers with humidity setting to control the room temperature. It can be difficult and I need more than one. Where I live too much humidity is never a problem.

With my upright I just tried to make sure it didn't drop below 30%, but now with my grand I notice problems with the sound immediately when it drops below 40% and I think the best compromise for me and the piano would be to keep it at 45%. Too much humidity tends to give me allergy symptoms.

To keep it at that level takes a lot of water though, I've sometimes had to fill the humidifier twice a day now when it's getting colder...I'm worried for the winter.
So I think I need to consider installing the system to the piano...

I have no doubt that in-piano systems help stabilize the RH in the space in and around the piano. But I think if those of you who are taking measurements to assure yourself that it's working would also take measurements on the other side of the room that you'd see it is also more stable.

If you believe that the system is specifically directing its effects into the piano, then you must also believe that the rest of the greater space will remain unchanged, as if no system were in operation. Right? For example, 35% RH opposite the piano, but a better reading near the piano, say 50%.

The above would be a very easy experiment to conduct, with the "non-climatized" part of the room serving as the control. I suspect that even with minute by minute readings, there would be relatively little lag, and the readings very similar.

Want a simpler experiment? Go take a hot steamy shower and watch the mirror fog up. The water vapor isn't contained in the shower enclosure. Also, leave the bathroom door open and the mirror is much less likely to fog up, because the vapor is exchanging much more readily into a greater space. It goes right out the door.

So, here's how I see it: yes, the systems are going to have an effect on the environment, but essentially no different than a room unit would. It essentially is a room unit, that just happens to be concealed inside the piano. You might as well just have a vicks vaporizer sitting nearby. I believe a dealer has recommended these here before (Master88er?), and another poster has described how to hook them up with a hygrometer to easily automate them. I have a whole-house system, because it gets very cold and arid here in Virginia where I live. The dryness aggravates everyone's sinuses, and my youngest daughter is prone to nose bleeds. It keeps the house nicely balanced, protecting my peeps, and the piano too.

So, again, I have no doubt it "works," but people are short-sighted when they think it's effects are locking in to the piano. It's impact is much greater than what's being assessed by taking readings in or near the piano.

To the extent that you can seal the piano up with a vapor barrier, or close it up, it will slow down the natural diffusion of humidity, but it won't stop it, because pianos are not air tight.

Regardless of the humidity discussion, how does a DC not affect the sound? I can just imagine all kinds of buzzing and creaking and vibrating coming from something like that.

This is true, in a way...

A hair dryer does remove moisture from hair, but technically it's only accelerating a process that would happen naturally. And the reason it would happen naturally is because the moisture content of wet hair is higher than the RH of the air.

Try staying under the shower head and drying your hair. Actually, don't do that, but you should get the point: if the surrounding area has the same moisture content as the hair, then the hair won't dry naturally, and neither would the hair dryer dry it. The hair dryer might evaporate some water, which would then diffuse into the greater space, cool, and RH would equalize again. And the hair would remain wet.

The above is how it works with a piano. Just like hair is as wet as the shower spray, the piano is as moist as its environment. Any change made in the small, to the piano's immediate environment, will quickly equalize with the greater environment until the marginal changes can add up enough to change the whole environment.

Wrong.

I sort of get this perspective, because I've often thought that people who sell them don't have the most objective opinions either. I've chosen not to buy one, but neither do I sell them, so I'm not biased either way. Anyway, I don't think you need to have one to understand the basic physical science behind how they work.

>My house varies between about 28% in the winter to 80% in the summer. If I use a de/humidifier near the piano (Yamaha C7), I can narrow that to about 35% to 70%.

Well that's a huge step in the right direction already. Much better than without. But 35-70 is still quite large. It sounds like the de/humidifier is not completely up to the job.

Also I believe it's better to put the humidifier a bit away from the piano, to dampen humidity swings as the device switches on. I suppose this is a whole-room humidifier

Retsacnal,

Over the past three years I have had four cheapie hygrometers and a sling psychrometer (I don't use it anymore. It was just to test the accuracy of the mechanical hygrometers.) One is in the piano, two are in the piano studio and one is in an adjacent room. The 3 exterior hygrometers all read nearly (+/-2%) the same, and vary from about 40-60% throughout the year. The piano hygrometer varies from about 48-54% in the same period. (My DC system is set for about 50%.)

The point is that there appears to be a microclimate in the piano. It does not reach equilibrium with the external environment as it is always reacting much more quickly to changes in its own environment. (I don't know what the hysteresis range is.) The other point to remember is that wood takes up moisture at a rate approximately five times the rate at which it gives up moisture.

Piano90X,

The DC, properly installed, causes no obvious change in the sound of the piano. I have had it on 2 of my three grands and played many institutional pianos with the system installed. So far, I have never heard a buzz or rattle. The system is cycling from dehumidifying to humidifying constantly. This cycling is completely silent. Ther are no mechanical switches or relays.

I had thought about installing a DC system and asked Bösendorfer master technicians about them during master piano classes I have taken with them in Vienna and they adamantly said no do not install one. So I haven't. I use a humidifier in the winter months and it isn't a major problem.

I'm confused by one of the posts above where someone said 40% would do major damage to your home. Why would that be? We have over 40% regularly in the summer and homes aren't damaged by it so why would they be in the winter when using a humidifier? My home doesn't seem damaged at all, just a lot more comfortable. Now, if there were no ventilation, that would be another story.

Steve
Bösendorfer 170

I also have thought about installing a DC system in my two vintage pianos-- but my tech advised he doesn't consider DC appropriate for pianos made in 1900 due to possible effects of heat on glue from this era.

Do any other techs have this opinion of DC systems in vintage pianos?