The H8908B Humidistat and H8908C Dehumidistat
(humidity controllers) provide automatic low voltage
control of humidifiers and dehumidifiers or ventilators,
respectively, in central heating and air conditioning sys-
tems. They have a spst, snap-acting, dust-proof switch
and are designed for wall or surface duct mounting.
When Installing this Product...
1. Read these instructions carefully. Failure to follow
them could damage the product or cause a haz-
2. Check the ratings given in the instructions and on
the product to make sure the product is suitable
for your application.
3. Installer must be a trained, experienced service
4. After installation is complete, check out product
operation as provided in these instructions.
Personal Injury Hazard.
Power supply can cause electrical shock.
Disconnect power supply before beginning
Location and Mounting
The styling of the H8908 is designed to blend with the
latest T8600 family of Honeywell Chronotherm® IV
Deluxe Programmable Thermostats. A mounting tem-
plate is included for mounting the H8908 next to the
T8600. The H8908 can also be mounted at any other
convenient location in the living area or equipment
room. See Fig 1.
NOTE: The H8908 electrical connections are not
shared with the thermostat.
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HOLE FOR WIRING
THE DUCT MOUNTING
Fig. 1. H8908B Humidistat.
Mount the control in an area with average
room temperature and average relative
The following mounting instructions are for mounting
the H8908 on the wall next to the T8600. When install-
ing the H8908 at another location, modify the procedure
to fit the installation.
1. Hold the mounting template (included) next to the
T8600. Select the mounting side for the H8908.
The template is reversible for mounting on either
the left or right side of the T8600. See Fig. 2.
2. Mark the holes for the two mounting screws
(included). Then mark the hole for the low voltage
wiring on the template that corresponds with the
side selected in step 1.
3. Remove the template and drill the holes.
4. Run low voltage wiring to the location and pull
about 6 in. (152 mm) of wire through the hole.
5. Plug the hole with nonflammable insulation to
prevent drafts from affecting the control opera-