Hi John,
You may have seen my posts a while back about running some room humidifiers here at CalArts. We have some "techno-pianos" that cannot take full Dampp Chaser system (with water tanks), due to the presence of electronics. On those instruments, we have DC humidistats and drying rods ONLY. Added moisture in those applications is achieved by the room humidifiers.
If low humidity is the only issue (in other words, high humidity is not also an issue at times), then a room humidifier alone with the appropriate capacity could certainly do the job. Please bear in mind, though, that the unit needs to be filled on a daily, or nearly daily basis (and, of course, kept plugged in!).
We use room humidifiers made by Venta. Their "comfort-plus" line includes a built-in humidistat. We have been using them for a couple of years now and have received good service from them.
One particularly fastidious private client has both a room humidifier AND a room DE-humidifier. Both units are governed by a very accurate digital "brain." (In addition, he also has DC systems on both pianos in the room. Did I mention that he is fastidious?)
Hope that helps,
Alan
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Alan Eder, RPT
Herb Alpert School of Music
California Institute of the Arts
Valencia, CA
661.904.6483
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