FWD: Is complete 5-Part Dampp-chaser unit always necessary?

[Farrell]

Hello. I have I few comments and questions interspersed in the post below. I
would really like to dig further into this humidity control thing. I find
that opinions are so divergent, I really wonder what is the best advice to
follow.

Terry Farrell

----- Original Message -----
From: <larudee@pacbell.net>
To: <pianotech@ptg.org>
Sent: Tuesday, June 19, 2001 11:26 PM
Subject: Re: FWD: Is complete 5-Part Dampp-chaser unit always necessary?


> Ryan,
>
> I definitely like the two-part system (humidistat and rod(s)for climates
> where low humidity does not
> occur.  It is not only less costly and maintenance free, but you also
> don't need
> as much drying power because you don't have a tank of water to deal
> with.

I agree completely. As someone else pointed out however, you need to be
aware that even if it is not real dry outside, if it is cool and indoor heat
is used, you really need to monitor the indoor relative humidity (RH) levels
to be sure that it is not getting real dry inside. I have monitored my home
extensively and other homes sporatgically, and have found that
central-air-conditioned homes in Central Florida generally have a maximum RH
of about 70% to 80% and minimum RH in the winter of about 35% to 40%. I am
using the little cheepy hygrometers sold by Pianotek, Damp-Chaser and others
for measurements. I have four of them and three of them are always real
close to each other - I think they are fairly accurate. In the winter we
sometimes have a rainy week and without the use of A/C, humidities in homes
can exceed the normal 80%. I have also observed a few RHs around 20% - but
these where only in homes of elderly folks who tend to really crank up the
heat in the winter.

>  I
> like to use the least powerful system that I can get away with, which is
> to say
> that when the ambient humidity is at its highest, the dehumidifier will
> be on
> most of the time.  I prefer this because it results in less and slower
> cycling,
> i.e. when the heat goes on, it tends to stay on for a longer time.  I
> find that
> this gives greater stability to the system because it is not changing
> from one
> state to another as frequently.

Maybe. Have you monitored your systems to see what RHs are achieved? Have
you measured the duration of the ON cycles?

> Lower wattage also reduces the risk of
> heat
> expanding parts of the plate or the strings in some uprights.

Again, maybe. If the rod is located close to the plate, and it is on most of
the time, might it not heat the plate (is this a problem?). Perhaps it would
be better for more rods and less duration.

>  Here in
> the San
> Francisco Bay area, where the humidity is usually between 40% and 75%, I
> find
> that 25W is usually enough for spinets and consoles, 35W for larger
> uprights,
> 50W for small grands, 75W-88W for larger grands and 113W-126W for
> concert
> grands.

Again, have you monitored RHS achieved or duration of ON cycles? Or are you
relying only on how the tuning seems the once or twice a year you see the
piano? (Obviously, a stable piano is what we are after, but only infrequent
visits to the piano to subjectively render an opinion on its tuning, may be
misleading - for me anyway, reams of data make me more comfortable.) I
usually recommend 50W for a console and 100W for a large upright. I have 220
Watts under my 5' 10" Boston grand. I find that during the winter, I rarely
find the system on. During the humid summer, it will run between 50% of the
time and when it gets really humid, perhaps 80% of the time. (The pitch and
tuning on my Boston is absolutely, rock solid - it just does not budge) I
found that with fewer rods, the sytem would stay on all the time and not
reduce the RH to targeted levels. I also use a dry calibration humidistat. I
use the dry because my own personal observations have been that the dry
calibration will cycle on and off at right around 48% to 50% RH. (I put the
hygrometers on top of the case beams - almost touching the soundboard - in a
variety of locations - and it never dries it out to less than about 45% RH.)
The normal calibration humidistats cycle on and off around 60%. Again, these
are observations that I have made in my own shop with the cheap hygrometers.
But what else can I do - until I buy a good hygrometer?

I talked to Bill Spurlock at the KC convention and he has a similar
philosophy to put in lots of power - that is what you have the humidistat
for. Lots of power means more rapid cycling, which in turn means more
consistent RH environment for the piano.

> I find that pianos with this system are more in tune after a year than
> pianos
> without it are after six months.  The caveat that I always tell my
> customers,
> however, is that they are not allowed to move the piano to a different
> climate.
> If they do, the system may not work as well unless modified to a full
> system.

Yup!

> I can understand Dampp-Chaser not being enthusiastic about this
> practice,
> because the piano could get sold and moved to another location and the
> system
> would no longer function properly, in which case the new owner might
> blame the
> manufacturer.  For most of my customers, however, I think the partial
> system is
> in their best interest, as long as they are fully informed.
>
> Paul Larudee
>
> Jeannie Grassi wrote:
>
> > Dear List,
> > This came to me for your consideration from Ryan Sowers, RPT:
> >
> > >>As technicians we try to educate our clients so that they can take the
> > best
> > care of their pianos. I have attended several classes on humidity
control at
> > conventions and talked with experienced technicians whose opinions I
> > respect. Combined with my a bit of personal experience with these
systems I
> > have become convinced that they are of substantial enough benefit that
we
> > are doing our clients a disservice if we are not actively promoting
these
> > products. However there is an aspect of humidity control that I do not
> > understand.  Is the humidifier component beneficial in environments
where
> > the relative humidity never drops below 42%? Since the humidifier is the
> > most expensive portion of the system and also the only part that
requires
> > routine maintenance it is tempting to recommend installing the
dehumidifier
> > and the humidistat only.  I called dampp-chaser and asked them if they
had
> > studied the effectiveness this and they said no and that the only system
> > they recommend is the complete system. Here in the Pacific Northwest the
> > indoor humidity practically never goes below 42 % except in cases where
the
> > client has wood heat. I believe in the value of humidity control, but am
I
> > wasting my client's money recommending the 5 part system when a simple 2
> > part system might be as effective?
> >
> > Sincerely,
> > Ryan Sowers RPT
> > Puget Sound Chapter<<
> >
> > Jeannie Grassi, RPT
> > Associate Editor, Piano Technicians Journal
> > mailto:jgrassi@silverlink.net