User’s Guide
Model 445815 Humidity Alert II
Humidity Indicator with Dew Point and Programmable Hi/Lo %RH Alarms
Introduction
Congratulations on your purchase of Extech’s Humidity Alert II
Remote Probe Hygro-Thermometer. Humidity alarms warn when
the %RH exceeds a pre-set HI or LO limit. The remote probe
conveniently mounts on the meter or extends for measurements
in ducts or remote locations. It also features Humidity and
Temperature adjustments. The unit can be wall-mounted or
placed on a flat surface using the fold-out stand. This
professional meter, with proper care, will provide years of safe
reliable service.
Meter Description
1. Temperature-Humidity Sensor
2. %RH Display
3. Dew Point Display
4. Temperature Display
5. %RH LED alarm
6. Max/Min push button
7. Reset push button
8. Sensor cable storage
9. Tilt Stand
10. Humidity calibration adjust
11. Temperature units switch (ºF/ºC)
12. Temperature calibration adjust
13. Wall hanger
14. Battery compartment
15. Audible Alarm ON/Off switch
1
RELATIVEHUMIDITY
MAX
A
L
E
R
T
Temperature
MAX
DEW Point
DEW Point
MAX
A
L
E
R
T
4
Humidity MoldAlert
15
Al.On
Al.Off
RHALARM
RESET
445815
13
11
O
C
O
F
5
8
MAX/MIN
9
14
10
12
Battery Replacement
The low battery flag will appear on the display when the battery
voltage is low. Replace the battery when this occurs.
Open the battery compartment by sliding the battery cover on the
rear of the instrument downward as indicated by the arrow.
Replace the 1.5V ‘AAA’ batteries and replace the cover.
Operation
Preparation for use
Open the battery compartment by pushing the cover on the
rear of the instrument downward as indicated by the arrow.
Remove the battery insulating strip and the protective film
cover on the LCD display.
Temperature Units
Select ºF or ºC units using the rear selection switch.
Audible alarm
Select or using the rear selection switch to turn the
audible alarm on or off.
Maximum / Minimum display
1. Press the MAX/MIN button. The highest value measured
since the Reset button was last pressed appears on the
2
3
6
7
display.
2. Press the MAX/MIN button again to display the lowest value
measured since the Reset button was last pressed.
3. Press the MAX/MIN button again to return to normal display
operation.
Resetting (clearing) the MAX/MIN memory
1. Press the MAX/MIN button to enter the MAX/MIN mode.
2. Press and hold the RESET button for 1 second to clear the
memory and start recording new max/min values.
Setting the %RH Alarm Limits.
1. Simultaneously Press and HOLD the MAX/MIN and RESET
button until “HI” and the stored HI %RH limit appears
flashing.
2. Press the RESET button to set the Hi %RH limit. Hold the
button in for rapid adjustment.
3. Press the Max/Min button. “LO” and the stored LO %RH
limit will appear flashing
4. Press the RESET button to set the LO %RH limit.
5. Press the Max/Min button to turn on or off the alarm. The
alarm icon
will appear in the display when the alarm is
active.
6. Press and hold the RESET button to save the settings and
exit the mode.
Alert
If %RH exceeds the HI limit or goes below the LO limit the
alert will be activated. The alert consist of two flashing
‘ALERT” icons in the upper display, a flashing red light (for 60
seconds) and an audible buzzer (for 60 seconds)
RELATIVEHUMIDITY
MAX
Calibration
A
L
E
R
T
Temperature
MAX
Humidity Mold Alert
RHALARM
DEW Point
DEW Point
MAX
A
L
E
R
T
MAX/MIN
RESET
445815
C
C
RH Calibration
1. Insert meter’s sensor into a salt reference bottle or humidity
chamber. The reference should be >70% RH.
2. Check the reading after 1 hour.
3. Adjust the RH calibration pot in ½ turn increments, waiting
for the display to update after each adjustment, until the
reading is within the accuracy specification.
Temperature Calibration
1. Place the sensor in a stabilized environment of
approximately 21°C.
2. Check the reading after 1 hour.
3. Adjust the temperature calibration pot in ½ turn increments,
waiting for the display to update after each adjustment, until
the reading is within the accuracy specification.
Specifications
Range Accuracy
Temperature -10 to 60oC
14 to 140
Humidity 10% to 99% + 4% RH within 25% to 85% RH
Dew Point -36 to 60oC
-32.8 to 140
Battery (2) 1.5V 'AAA' cell
Weight 6 oz (169g)
Dimensions Display: 4.3x3.9x0.8” (109x99x20mm)
Probe: 0.57” (14.4mm) Dia.: 1.67”(42.4mm) L
Cable length 18” (457mm)
Visit us at www.TestEquipmentDepot.com
Back to the Extech 445815 Product Page
+
o
F
1.0oC within -10oC to 50oC
1.8oF within 14oF to 122oF
+
o
C or 32 to 122oF
o
C. @ 20oC
o
F @ 68oF
o
F
and 0 to 50
+/-2
+/-3.6
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Test Equipment Depot - 800.517.8431 - 99 Washington Street Melrose, MA 02176
FAX 781.665.0780 - TestEquipmentDepot.com
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