Dampp Chaser and Grand Action

[David Love]

If sluggishness were the only problem then it could be treated, but since
the problems come from changes in humidity, then treating sluggishness is
only as good a fix as the humidity is constant.  What I am trying to treat
is changes in friction that come with humidity swings.  Addressing the
action centers won't accomplish that.  The humidity needs to be regulated
in some manner.  Short of regulating the entire house, I am looking for an
alternative.  Convection problems could be treated by closing the lid of
the piano when not in use.  Speculating on the potential problems is easy,
but I'm wondering if there is any real data on methods of controlling the
humidity inside the action cavity and effects on the pinblock.  Certainly a
system of humidification of the soundboard area during a very low RH period
doesn't help the pinblock.  And my guess is that a low wattage heater bar
connected to a humidistat would not reduce the RH around the block to a
lower level than 42%.  So, why, then, would a controlled dehumidification
system hurt it?  Am I wrong in that a humidistat controlled action cavity
is likely to reach levels which are too low?  I would guess that the low
conductivity of wood would render a low wattage heater bar relatively safe
if located below the level of the flanges on the action bracket.  

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: <JIMRPT@aol.com>
> To: <pianotech@ptg.org>
> Date: 8/26/2003 10:24:17 AM
> Subject: Re: Dampp Chaser and Grand Action
>
>
> In a message dated 26/08/03 11:35:54 AM, <mfarrel2@tampabay.rr.com>
writes:
>
> << Why is a Dampp-Chaser rod "not compatible ...... period" in a grand
>
> action cavity? >> (T.F.)
>
>  For two reasons:
> 1. Heat rises and the first thing it will run into in the action cavity
is 
> the pinblock.
> Heat doing what it does, with or with a humidistat, will over time cause 
> premature failure of the pinblock.....this ain't rocket science. :-)
> 2. The DC installed in any area of the action cavity draws outside air
into 
> the cavity through convection as we would expect and verrrrry little of
this 
> 'warmed' air will actually get to the jacks/balanciers...this makes any
benefit 
> from a cavity installed DC problematical at best. Because of the openess
of 
> the cavity/block/platewebbing/capo area there is never any sustained
drying of 
> anything...well except for the block.......
>
>  No amount of "insulation" will stop the pinblock from drying out over
time. 
> The answer to this 'sluggishness' problem is to solve the real problem(s)
and 
> not treat the symptoms.........period.
> My Opinion.
>  Jim Bryant (FL)
>
>
>
>
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