Installation and Maintenance
EHU-600 Series Humidifiers
9
The EHU-600 as shipped, is usually set to accept input signals from
the Armstrong control humidistat. To adapt the EHU-600 to a different
type of control humidistat (with characteristics as listed above) jumper
BJ2 must be changed on the printed circuit board (See Fig. 9-1). For
the Armstrong humidistat select the jumper position labeled 1.9-
3.9V. If the desired humidistat has the characteristics 4-20 milliamps
or 2-10 volts, change the jumper position to the position labeled 2-10V/
4-20MA. If the desired humidistat has the characteristics on/off or
0-135 ohms, change the jumper to the position labeled 0-135
Ω
ON/Off.
Make sure main power is off when changing any PC board jumper
setting. See the troubleshooting section of this manual for additional
information on humidistat wiring.
Selecting The Proper Location: The control humidistat should be
located where it will be exposed to the average air condition of the
space to be humidified. Avoid areas of restricted air circulation, or loca-
tions where the sensor will be subjected to air drafts, localized heat, or
moisture sources such as coffee machines, computer blower outlets,
doors to other rooms, or windows that can be opened.
Wall-mounted control humidistats (Armstrong Part C1471) are
usually installed 4 ft. to 5 ft. above floor level. Often, the best location
is beside a thermostat that controls temperature in the same space
that is to be humidified, if that location meets the above criteria.
Duct-mounted control humidistats (Armstrong Part C1472) are also
available for installation where sensing and control from return air
or exhaust air ducts is preferable.
Mounting The Armstrong Control Humidistat
Caution: Do not check humidistat circuit with ohmmeter or direct
current with sensing element installed. Circuit may be checked
without sensor installed.
Wall Mounted Control Humidistat. The wall mounted unit is designed
to mount on a standard electrical outlet box. Mounting screw holes are
provided in the top and the bottom of the back plate. See Fig. 9-2.
Duct Mounted Control Humidistat. The sensor is mounted on the
end of the tube extending into the duct – not beneath the humidistat
cover. The duct mounted control humidistat requires a 1 1/4" diameter
hole in the side of the duct. See Fig. 9-3. See Figure 10-3 or 8-5 for
wiring terminals and overall wiring diagrams.
Operation And Adjustment Of The Armstrong Humidistat.
To set the Armstrong modulating humidistat to maintain a desired
relative humidity, remove the outer plastic cover and verify that the
number/color coded sensor element installed is in the RH control range
desired (see Fig. 10-1). Figure 10-2 specifies the number/color code
and corresponding humidity set point control range for each sensing
Figure 9-1: Location of Selector Pins
on Printed Circuit Board
Figure 9-2: Wall Mounted Control
Humidistat
Figure 9-3: Duct Mounted Control
Humidistat
Capacity Stepping
Selector
Display Connector
Socket
Stat Grounding
Selector
Stat Type
Selector
T
est
Capy S
tep
Normal
Mounts
on std.
2'' x 4'' box
(screws
provided)
Sensor
4-3/8''
2-7/8''
1-5/8''
2-7/8''
4-3/8''
3-1/2''
4-1/16''
1-1/4'' Max.
Sensor
10''
3-5/8''
1.9-3.9 V
2-10V-4-20 MA
0-135 v On/Off
MCM Header
GND
Float
