DAVIS Wireless Temperature/Humidity Station User manual

Product#7859&7860
S
TANDARD
& I
NDUSTRIAL
E
XTERNAL
T
EMPERATURE
/
H
UMIDITY
S
ENSOR
I
NSTALLATION
M
ANUAL
The External Temperature/Humidity Sensor (T/H Sensor), may be used with
the Weather Monitor II
®
, GroWeather
®
, Energy EnviroMonitor
®
, and the
Health EnviroMonitor
®
. The T/H Sensor enables you to display temperature
and humidity-related conditions. For a complete list of the conditions you may
display using the T/H Sensor, consult your station manual.
Components
The T/H Sensor includes the following components. Please make sure you
have all listed components before continuing.
✦
Temperature/Humidity Sensor with cable
The standard version comes with a 40’ (12 m) cable. The industrial ver-
sion comes with a 16’ (5 m) shielded cable.
✦
Five #4 x 1/2" pan headself-threading screws
✦
One #4 Flat Washer
✦ One Cable Clamp
Tools and Materials Needed
In addition to the components listed above, you will need the following tools
and materials. Please be sure you have everything you need before beginning
the installation.
✦
Small Phillips-head screwdriver
✦
Drill and 1/16” to 3/32” (#43, 2 mm) drill bit.
✦
Cable clips or weather-resistant cable ties with screw holes or other
means for mounting. Do not use staples.

Page2 Standard&IndustrialExternalTemperature/HumiditySensor
Testing the T/H Sensor
Be sure to test the sensor before installing it.
1. Attach the sensor cable to the appropriate connector on the junction box/
sensor interface module (SIM). Refer to the T/H Sensor installation infor-
mation shown below and on the following pages.
2. Press the appropriate key on your console as necessary to make sure you
are getting an outside air temperature reading on the console.
3. Press the appropriate key on your console as necessary to make sure you
are getting an outside humidity reading on the console.
Installing the T/H Sensor
Follow the instructions in this section to install your sensor. Make sure you
read “Choosing a Location for the T/H Sensor” on page 4 as it contains impor-
tant information concerning placement of the sensor.
Typical Weather Monitor II Installation
The illustration below shows a typical T/H Sensor installation for the Weather
Monitor II.
Typical Weather Monitor II installation

InstallingtheT/HSensor Page3
Note: You may also use the Radiation Shield and Sensor Mounting Arm (pictured below) if desired.
Typical Standard GroWeather/EnviroMonitor Installation
The illustration below shows a typical Standard T/H Sensor installation for the
GroWeather, Energy EnviroMonitor, or the Health EnviroMonitor.
Typical standard GroWeather/EnviroMonitor installation

Page4 Standard&IndustrialExternalTemperature/HumiditySensor
Typical Industrial GroWeather/EnviroMonitor Installation
The illustration below shows a typical Industrial T/H Sensor installation for
the GroWeather, Energy EnviroMonitor, or the Health EnviroMonitor.
Typical industrial GroWeather/EnviroMonitor installation
Choosing a Location for the T/H Sensor
Use the following suggestions to find a suitable location in which to mount the
sensor. Care taken in choosing a location improves the accuracy, reliability, and
durability of the sensor. The ideal location would be on the North side of the
building in the Northern Hemisphere, or the South side in the Southern Hemi-
sphere.
Note: When you choose a location for the sensor, always take into consideration nearby objects. Objects
which heat up in direct sunlight such as pavement, or that produce radiative cooling effects such as a
fountain, may affect the temperature of the air in the vicinity which can affect the temperature and
relative humidity readings from the sensor.

InstallingtheT/HSensor Page5
Look for a location which satisfies the following requirements:
✦ Ideally, install the sensor in a Davis radiation shield.
✦
Place the sensor in a location shielded from rain and other sources of
water such as rainfall runoff.
CAUTION: It is important that no water strike the sensor.
✦
Place the sensor in a location where it will not be in direct sunlight and
where it will have limited exposure to reflected sunlight.
If possible, place the sensor at least 5 feet (1.5 m) from any surface which
is exposed to direct sunlight because the heat from this surface may
affect air temperature readings in the vicinity.
✦
Limit the exposure of the sensor to the open night sky.
If you are unsure about a location's exposure to the night sky, check for
dew at that location on a light dewy morning. If the area is dry, the loca-
tion should work well.
✦ Place the sensor in a location at least 10 feet (3 m) away from any lights
or lamps.
✦
Place the sensor at least 5 feet (1.5 m) from man-made sources of heat,
such as vents.
✦
Keep the sensor away from AC power lines.
Keep the sensor and most of the cable at least 10 feet (3 m) from 110 VAC,
60 Hz utility power. Do not run the sensor cable parallel to house wiring.
Mount the sensor at least 30 feet (9 m) from high-voltage power lines
and transformers.
✦
When running the sensor cable, try not to run it across large metal
objects (e.g., aluminum siding).

Page6 Standard&IndustrialExternalTemperature/HumiditySensor
Mounting the T/H Sensor in a Davis Radiation Shield
In order to attach the External Temperature/Humidity Sensor (T/H Sensor) to
the Radiation Shield, you will need to expose the Radiation Shield’s closed
plate. Refer to your Radiation Shield installation manual for complete instruc-
tions on mounting the Radiation Shield.
1. Position the T/H Sensor
over the four mounting
posts on the closed plate,
lining up the holes in the
mounting posts with the
holes in the T/H Sensor’s
casing as shown.
Note: Make sure you orient the T/H Sensor with the long side of the sensor parallel to the long side of
the plate.
2. Using three #4 x 1/2” pan head self-threading screws, attach THREE
CORNERS of the T/H Sensor to the closed plate.
Do not attach the final corner yet.
3. Place the cable clamp around the sensor cable approximately 4” (10 cm)
from the T/H Sensor.
4. Attach the cable clamp to the remain-
ing corner of the T/H Sensor and to
the closed plate (using a #4 x 1/2”
pan head self-threading screw and a
#4 flat washer) so that a loop of cable
is formed.
Make sure to mount the clamp with
the flat side up and the bulge side
down. Tighten the screw completely
so that the cable cannot move within
the cable clamp.
Mounting the T/H Sensor without a Radiation Shield
1. If necessary, disconnect the sensor cable from the junction box/SIM.
2. Hold the sensor housing against the mounting surface and use a pencil to
mark the location of the four holes on the sensor housing.
3. Use a 1/16” or 3/32”drill bit (2 mm) drill bit to make pilot holes in these
locations.
4. Drive the four #4 x 1/2" pan head self-threading screws through the holes
on the sensor housing and into the mounting surface.
#4 x 1/2" Screws (3)
Cable Clamp

InstallingtheT/HSensor Page7
5. If using the industrial version
of the sensor, secure the cable
to the mounting surface using
the cable clamp, a #4 x 1/2"
screw, and a #4 washer.
6. Connect the sensor cable to
the junction box/SIM.
Routing Sensor Cable
To prevent fraying or cutting of the cable where it is exposed to weather, it is
important that you secure it so it doesn’t whip about in the wind.
✦
Use cable clips or weather-resistant cable ties to secure the cable.
✦
Place clips or ties approximately every 3 to 5 feet (1 to 1.5 m).
CAUTION: Do not use metal staples or a staple gun to secure cables. Metal staples—especially when
installed with a staple gun—have a tendency to cut the cables.
Securing cable (standard cable shown)
Note: When running the sensor cable, try not to tug on the cable in such a way as to loosen the connec-
tions between cables. Also, make sure the sensor cable is not so taut that connections loosen or pull
free due to the strain. Many sensor problems occur because cable connections come loose. If you
need to check the cable connection to the sensor itself, see the section below.

Page8 Standard&IndustrialExternalTemperature/HumiditySensor
Detaching the Cable from the Sensor
If you ever need to remove the sensor or check the sensor cable's connection to
the sensor and want to leave the cable in place when you do so, follow the pro-
cedure below.
To Detach the Sensor Cable from the Sensor
1. Remove the front piece of the sensor housing by removing the two screws
on top of the housing.
2. Once the screws are out, lift the front
piece away.
Keep the screws and the front piece in a
safe location until you reattach the front
piece.
3. Detach the cable connector from the pin
header by pulling straight back on the
connector. Do not tug on the cable itself to
detach the connector.
To Reattach the Sensor to the Cable
1. If necessary, remove the front piece from the
sensor as described above.
2. Making sure the tab is on top of the cable con-
nector, slide the cable connector over the pins
on the pin header.
3. Replace the front piece. Make sure the sensor
cable runs through the cable slot created by
the front piece and the sensor housing.
4. Secure the front piece by replacing the two
screws.
Removing the front pieece
Connecting the sensor cabble

DisplayingDewPointontheWeatherMonitorII Page9
Displaying Dew Point on the Weather Monitor II
Follow the directions below to use the dew point function on your Weather
Monitor II. For a description of dew point, consult the appropriate section of
the Weather Monitor II manual.
Note: Instructions for displaying dew point are contained in the GroWeather, Energy EnviroMonitor, and
Health EnviroMonitor manuals.
You may display dew point in either ˚F or ˚C. The Weather Monitor II records
high and low dew points, and has an alarm to alert you when temperature
comes within 2˚F (1˚C) of dew point.
To Display the Current Dew Point
Press DEW. The dew point and the words DEW POINT appear on the display.
Current dew point
To Change the Unit of Measure
1. Press DEW.
2. Press UNITS.
The console display switches from ˚F to ˚C or from ˚C to ˚F. To return to the
previous format, press UNITS again
To Display High and Low Dew Points
1. Press DEW.
2. Press RECL.
The high dew point appears. After a few seconds, the display will show
the time the high was recorded, and then the date it was recorded.
3. Press RECL again.
The low dew point appears. After a few seconds, the display will show the
time the low was recorded, and then the date it was recorded.
4. Press any key to exit.

Page10 Standard&IndustrialExternalTemperature/HumiditySensor
To Clear High and Low Dew Points
1. Press DEW.
2. Press RECL once or twice to select the high or low dew point, as desired.
3. Press CLEAR and hold it down.
The value will flash several times. When the value stops flashing it means
that the high/low has been cleared. It is not uncommon for another high/
low reading to appear almost immediately. This is simply because the
Weather Monitor II is constantly in the process of recording new highs and
lows.
4. Press any key to exit.
High and low dew points are independent of each other. Clearing the high
dew point does not clear the low dew point, and clearing the low dew
point does not clear the high dew point. You must clear each dew point
individually.
To Set the Dew Point Alarm
1. Press DEW.
2. Press ALARM.
3. Press ENTER.
The display will show 2˚F (1˚C) which is the only possible setting for the
dew point alarm.
Dew point alarm
4. Press any key to exit.
The alarm sounds if dew point and temperature are within 2˚F (1˚C).

WeatherMonitorIIHumidityCalibrationNumber Page11
Weather Monitor II Humidity Calibration
Number
Versions of the Weather Monitor II manufactured after 1994 allow the user to
set a calibration number (CAL) for outside humidity. To determine which ver-
sion of the Weather Monitor II you have, look at the manufacturing code (Mfg.
Code) on the underside of the console. If the manufacturing code begins with
the letters "M" or “MB” (e.g., "MB30302F41") you will not be able to set CAL for
Outside Humidity.
Note: The GroWeather, Energy EnviroMonitor, and Health EnviroMonitor allow the user to set a calibration
number for outside humidity. See the appropriate manual for instructions.
Change CAL if you wish to adjust the Weather Monitor II's outside humidity
reading. Note that a calibration number exists for outside humidity only.
Calibrated Outside Humidity = Outside Humidity + CAL
Default CAL = 0.
Note: For general information on CAL numbers, consult the Weather Monitor II manual.
Troubleshooting
While your T/P Sensor is designed to provide years of trouble-free operation,
occasional problems may arise. If you are having a problem with your unit,
check the following troubleshooting tips before sending the T/P Sensor in for
repair. If, after checking these procedures you are unable to solve the problem,
contact Davis Technical Support for further instructions (See “Contacting
Davis Instruments Technical Support” on page 12). Please do not return your
unit for repair without receiving prior authorization.
Troubleshooting Tips
• Carefully check all cable connections from the sensor to the console. Cable
connections account for a large portion of the potential sensor problems.
• Connections should be firmly seated in the jacks and plugged in straight.
• If you think a connection may be faulty, try jiggling the cable while looking
at the display. If a reading appears intermittently on the display as you jiggle
the cable, the connection is faulty.

Product Numbers: 7859 & 7860
Davis Instruments Part Number: 7395.027
External Temperature/Humidity Sensor, Standard & Industrial
Rev. G Manual (3/13/2001)
This product complies with the essential protection requirements of the EC EMC
Directive 89/336/EC.
© Davis Instruments Corp. 2001. All rights reserved.
3465 Diablo Avenue, Hayward, CA 94545-2778
510-732-9229 • Fax: [phone]
E-mail: [email protected] • www.davisnet.com
Contacting Davis Instruments Technical Support
If you have any questions about our products, please call Davis Technical Sup-
port. We’ll be glad to help. Most questions can be answered while you’re on the
phone. You can also email us for support, or visit our website. Sorry, we are
unable to accept collect calls.
Voice Line: 510-732-7814, Monday - Friday, 7:00 am - 5:30 pm, PST
Fax: Line 510-670-0589
Email: [email protected]
World Wide Web: www.davisnet.com
S
PECIFICATIONS
Temperature
Range: -50˚ to 140˚ F (-45˚ to 60˚ C)
Resolution: 0.1˚ F (0.1˚ C)
Accuracy: ± 1˚F (± 0.5˚C)
Humidity
Range: 0 to 100% RH
Resolution: 1% RH
Accuracy: ± 3%