[CAUT] Organs and RH

Geoffrey Pollard gpollard@greenway.usyd.edu.au
Wed, 24 Nov 2004 12:20:10 +1100


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Hi Jim,

We have a similar situation at the Sydney Conservatorium - organ and 
harpsichord in the same room. It is on the north side of the building 
and sun streams through the windows especially in summer ( southern 
hemisphere, for those to whom this sounds wrong!), and plays havoc 
with the RH and temperature. There is AC but no humidity control for 
the room.

We have as much if not more trouble with the organ tuning, due to the 
RH and temp changes, than with the harpsichord. Organ tuning is much 
less frequent and more expensive, so the organ is in poor shape a lot 
of the time. As you may know, when RH and temp change, the pitch of 
metal pipes and wooden pipes move in opposite directions  - **%$@!

Regarding airflow through the organ, I don't know how it affects the 
overall room condition but I have been told by an organ builder that 
the forced flow of low RH air through an organ will lead to rapid 
damage to wooden pipes.

Our fix is to lock the AC control at 21 degrees and put tinting film 
on the windows.

I too have my doubts as to the effectiveness of a DC system under the 
harpsichord. As cost is the issue, even a smaller, therefore cheaper, 
room unit will minimise the swings. Not perfect, but perhaps no 
longer damaging to timber and somewhat more stable tuning.

The college may not believe that one harpsichord warrants a room 
unit, so base your argument on potential damage to the $360,000 organ 
and you might get your two birds!

Good luck,
Geoff Pollard
Piano Technician
Sydney Conservatorium of Music




>List,
>
>Does having a large pipe organ in the room affect the RH? By that I 
>mean, does all the air passing through an organ's pipes dry out the 
>air and/or does the pump/bellows compress air and make more/less 
>moisture?
>
>Thanks,
>Jim Busby BYU
> 

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