Duct mounted ultrasonic humidifiers

Has anyone had any experience with duct-mounted ultrasonic
humidifiers in historic house museums?

I have been asked by a client to collect information on others'
experiences with these because they are being recommended for
installation as part of an environmental improvement project for an
historic house museum.  Much of the building is historic, but
administrative wings and educational facilities have been added over
the last two decades.  The building is located in one of the
mid-Atlantic states of the US and the ambient climate ranges from
hot summers with elevated RH to winters with periods below freezing.

The current heating and humidification systems have been cobbled
together using an assortment of residential equipment.  Much of the
equipment is at the end of its service life.  Environmental
monitoring program has documented extreme swings in both temperature
and relative humidity throughout the building with elevated RH (in
excess of 65% )during the summer and low RH (below 20%) in the
winter due to the heating systems.  There is no vapor
barrier/moisture retarder in the walls and many of the windows are
single glazed.  Furthermore, there have been recurring problems with
mold in portions of the building due to problems with building
envelope and inaccessible leaks.

Unfortunately, the engineer retained for the upgrade has had no
experience with museum buildings and has little experience with
historic buildings.   In addition to focussing most of his efforts
on temperature control for human comfort, he has recommended the
installation of duct-mounted ultrasonic equipment for humidification
in critical areas during the winter.

I am providing reference information to my client on ultrasonic
humidification systems and the problems associated with them, but
the museum's director really likes the system as it has been
described and this may be the system which will be installed.

We want to know what others' actual experiences have been with these
systems. ie. have they performed as you desired?  how have you
provided the required clean water? etc.

We are interested in hearing both positive and negative feedback.
If desired, you can respond to me off of the List but this might be
of interest to others out there.  If you contact me off the List and
request confidentiality, I will assure it.  We are just interested
in receiving as much real information as we can get so that we know
what the institution may be getting itself into.  If duct-mounted
ultrasonic humidification systems are a really, really bad idea, we
need to be able to say so.  Or, at least document the fact that "red
flags" were raised, but that the administration proceeded despite
warnings.

Wendy Jessup
President and Conservator
Wendy Jessup and Associates, Inc.
210 Little Falls St., Suite 203
Falls Church, VA 22046
703-532-0788
Fax: 703-532-1661

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                  Conservation DistList Instance 10:63
                Distributed: Wednesday, January 15, 1997
                       Message Id: cdl-10-63-008
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