Climate Control; DC thoughts and concerns

Sarah Fox sarah@gendernet.org
Fri, 11 Apr 2003 10:49:34 -0400


Hi all,

I've been reading the soundboard torture and killer octave posts with
considerable interest.  One of the results of these posts has been a lot of
comments to the effect of, "It surely goes to show how important it is to...
(insert some climate control maxim here)."

This has all started me to thinking about the climate control situation
around my own piano.  You see, I have a very difficult house.  Unless I were
to put my piano up against the fireplace or in the kitchen against the sink,
I have no usable interior walls.  Perhaps a bedroom?  I think the piano is
bigger than any of the bedrooms, aside from the upstairs master.  Bathrooms
are not a likely option.

Kidding aside, my exterior walls are my only option.  They are each around
75% glass (double-paned) and are where the heat registers are located.  I
realize exterior walls are not as significant a problem for a grand piano as
an upright, but should I still be concerned?  Of course I took the
precaution of blocking the heat registers in the room and allowing the room
simply to get the cross-flow from the adjacent rooms -- still quite
comfortable.  I spaced the piano about 2 feet from the window, and I have a
ceiling fan in the room to keep the air stirred/mixed.  During the dead of
winter (Ohio), I have insulated drapes for protection.  Is anything about
this arrangement problematic???

I am also about to install climate control devices.  I will be putting a DC
dehumidifier system in the piano for the moderate months.  (The piano will
soon be making a move to a warm, humid climate, so I will definitely need
this.)  I am left wondering about the humidification end of DC's system,
though.  I'm not sure I entirely trust the thing.  I'm also left wondering
whether a tiny column of water vapor from the humidifier will really spread
over an entire sounding board and not just condense in the middle and/or
waft away.  The system also presupposes that the moisture doesn't just
evaporate back out of the board on the top-side, resulting in a MC still
somewhat less of where it should be.  Finally, it appears to me that the
heater bars and humidifier would be alternately fighting each other in the
complete system.  Is it really smart to heat the board during dry
conditions, even if the (tiny) humidifier is also adding moisture?  Would
this not speed moisture loss on the top side?  It doesn't compute.

It seems to me a much better approach would be to humidify the area.  My
house dropped to a low of 28% RH this winter -- not so low as to throw me
into a panic, but low enough that my piano complained somewhat.  Anyway, the
DC system cycles over about a 12% RH range, as I recall.  It would only take
an additional 8% RH to put my house at the low end of this range.  Fifteen
percent would put my house in the middle of the range.  Would this small
amount of added humidity really pose a problem for my house?

I figure I could humidify the house to a minimum of 40% RH, using a
whole-house humidifier/humidistat system.  Then the DC heater bars could
kick in during higher humidity conditions to drop the microclimate RH to its
36-50% RH range during the moderate months.  There would of course be no
heater bar activity during the winter.

If I opt for whole room (vs. whole house) humidification, how far away from
the piano should the humidifier be?  (I would be using an ultrasonic unit
with distilled water.)  Remember that I have a ceiling fan to keep the air
slowly stirred.

Misc. concerns about the DC:

The same would be true of the dehumidification process as the humidification
process:  Heat would escape the soundingboard from the topside, and so the
effective temperature of the board would be roughly the numerical average of
the air temperature above and below the board.  Thus, the board would not
really be kept at its target MC.  The error would increase in direct
proportion to the overall magnitude of correction.  Let's say the ambient RH
is 100%, and the DC system raises the underside temperature to achieve an
ambient RH of 42%.  The net effect, I believe, (making liberal assumptions
here) would be an effective overall RH of 71% in the microclimate
surrounding the board.  If there were also a heater bar under the closed
lid, conditions would of course be better.  It seems to me that the DC is
only really effective at fine-tuning the RH.  Perhaps the prudent piano
owner would also keep a room/household dehumidifier/humidistat running to
keep the RH down to a max of, say, 60%?

In the grand installation, there's no heater bar behind the action, under
the pin block.  Why?  Would it not make sense to have a second humidistat
and heater bar -- perhaps attached to the backside of the action?
(Incidentally, the need for keeping the MC of my pin block and action parts
up during the winter makes me believe all the more in whole-room/house
humidification.)

I don't know if I'm being too compulsive here, but the little soundboard
torture experiment....  Wow!

Any advice and/or perspectives would be greatly appreciated.

Peace,
Sarah Fox,
Chilly Columbus, OH



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