High humidity in winter?

[MBrat70179@AOL.COM]

I've recently received a call about an old upright in a church.  Their 
complaint is that the humidity is too high.  I asked if they are having 
tuning instablity.  He said not really, but the keys are sluggish.  This has 
been a continual problem for the past 50 years, as the church is situated 
near several water sources.  Including the basement.  They do have a 
dehumidifier in the basement.  He says that during the summer there will be 
mildew on the hymnals.  That's how bad the problem is.

On further questioning he says the church is not heated during the week.    I 
assume that when the heat is turned on the piano "sweats" causing the keys to 
swell.  Is this is how the moisture is introduced in the winter?

Another "tech" advised that the dampp-chaser systems are junk.  In this 
situation I don't know if the system will work or not.

My question is:  How much will the humidity be reduced throughout the 
instrument if a dampp-chaser is installed.  I know it will improve things, 
but will it work throughout.  And will the system be able to compensate for 
the "sweating" that occurs.


Mike Bratcher 
Associate Member