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

[Farrell]

> In either case the RH bounces back and forth between the trigger points
> of the
> humidification and dehumidification systems.  I don't see that bouncing
> back an
> forth faster makes the environment more consistent.
>

No, I would agree that it likely does not make much difference - either way
should be OK, as long as the system is maintaining proper RH. But, what the
rapid cycling does indirectly do for you is that it means you have reserve
power, so that when the RH in the room goes way up, your system can still
handle it and achieve targeted RH.

> When the humidity is high (65% or more), I rarely find my customers'
> systems in
> the "off" mode.

Then, what happens when RH goes up to 75% or more? I should think that it
means that the system would just stay on, and not lower RH to the targeted
value, if it is apparently maxxed out trying to lower piano RH when room RH
is at 65%.

Terry Farrell

----- Original Message -----
From: <larudee@pacbell.net>
To: <pianotech@ptg.org>
Sent: Wednesday, June 20, 2001 10:43 PM
Subject: Re: FWD: Is complete 5-Part Dampp-chaser unit always necessary?


> Farrell wrote:
>
> > 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.
>
> Terry,
>
> The 40% to 75% refers to humidity measured at the pianos of my clients.
>
> > Have you monitored your systems to see what RHs are achieved? Have
> > you measured the duration of the ON cycles?
>
> When the humidity is high (65% or more), I rarely find my customers'
> systems in
> the "off" mode.  When it is lower it is sometimes off, sometimes on.
> Obviously
> more off the lower the humidity.
>
> > > 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.
>
> There was a thread on this subject some time ago (2 months?).  One
> customer of
> mine had a large upright moved from Fresno to Berkeley.  It had a full
> D-C
> system with a 50W rod.  It was one of the few times I encountered the
> problems
> discussed on the thread having to do with heat.  Not a lot of proof, but
> indicative.
>
> > >  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 do not mean to recommend my figures to everyone.  I am only saying
> what seems
> to work here, where we don't encounter extremes in either direction.
> When I
> worked in Saudi Arabia (in seaside locations where the humidity ranged
> from 30%
> to 100% almost every day), I installed much more robust systems.
> However, Ryan
> was asking about a particular situation.
>
> > 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.
>
> In either case the RH bounces back and forth between the trigger points
> of the
> humidification and dehumidification systems.  I don't see that bouncing
> back an
> forth faster makes the environment more consistent.
>
> Paul Larudee