INSTRUCTION MANUAL
DTH31
Digital Psychrometer
1-800-547-5740 • Fax: (503) 643-6322
www.ueitest.com • email: info@ueitest.com
Introduction
The DTH31 Digital Psychrometer is an advanced handheld humidity and
emperature meter. Its triple display shows three parameter readings
t
imultaneously and includes a second temperature probe for external
s
measurements. It has everything you need to charge an air-conditioning
system and determine heating, cooling, and ventilation needs. It gives
you incredible fast and accurate wet bulb, dry bulb, and dew point
easurements. Nothing compares to this fully featured, hand-size
m
digital psychrometer.
4. ∆T/WB: Switch between ∆T, WB and T2.
T2 (∆T=T2-DP, T2=External Temp.)
˚C/˚F) - Centigrade/Fahrenheit:Toggles between these two
5.(
tandard scales.
s
.
6
N/MX:
M
RESET
• Reset MIN/MAX memory
• Display minimum value of memory
• Display maximum value of memory
Features include
• Triple display, RH, dry bulb and wet bulb temp.
• C/F selectable
• Turnable cap to protect sensor
• T2-Air temp. and T2-Dew Point
• Data hold
• MIN/MAX
• Automatic power off
Safety Notes
Before using this instrument, read all safety information carefully. In
this manual the word "WARNING" is used to indicate conditions
or actions that may pose physical hazards to the user. The word
"CAUTION" is used to indicate conditions or actions that may
damage this instrument.
Controls and Indicators
Buttons
LCD Display
1
2
3
4
1. RH%
2. Air Temperature (T1)
External
robe Port
P
5
6
7
1
3
5
2
4
6
1. ON/OFF - “ “ : Turns unit on and off.
2. Hold - Data Hold: Freezes data input.
• “HLD” appears in upper right corner of display
• View frozen data for any of these functions: C/F, Td/WBT, MIN/MAX
T
E
S
• Cancel hold by pressing “R
E
”
• “ “ + HOLD = non-sleep mode (default setting is auto-sleep
in 5 minutes)
3.
∆T/DP : Switch between ∆T, DP and T1.
T1 (
∆T=T1-T2, T1=Air T
emp.)
3. T1 - T2*
4. Dew Point
5. External Temperature (T2)*
6. T2 - DP*
et Bulb
7.W
*Not available without external probe connected.
DTH31-MAN
P. 1
Operating Instructions
Data Hold Function
1. Press “HOLD” button until “HLD” appears in display.
The current reading is now held and will not change until the
•
HOLD function is cancelled (Fig 3)
(Fig 1)
WARNING!
Be sure to open the sensor protection cap before taking measurements.
Auto Power Off (Sleep Function)
Unit will turn itself off after ten (10) minutes of non-use (factory
programmed). The auto power off delay offers 2, 5, 10, 20, 40, and
60 minute options. To change auto power off:
1. Press “ “ + HOLD buttons.
2. When “ ” appears in the LCD, release “HOLD” button.
Unit is now in non-sleep mode.
2. Press “
HOLD” button again to cancel.
Hold function can be used for humidity, dew-point, dry bulb/T1,
•
Ext. Temp./T2, wet bulb and temp. differential
(Fig 3)
Dew Point Function
1. Press “ “ button until “DP” appears in the display. Select dew
point, T1 or delta T value in any mode while internal temperature
is active (Fig 4).
Mode Options
1. Turn the protective cap to the open position (Fig 1).
2. Press “ “ button to turn the unit on.
3. Press “˚C/˚F” button for 1 second to convert readings to desired
unit. Temperature relative humidity and wet bulb measurement
will be displayed simultaneously (Fig 2).
(Fig 2)
(Fig 4)
Wet Bulb Function
1. Press button until “Wb” appears in the display (Fig 4).
NOTE: WB is always visible without external probe.
External Temperature Function
1. Plug the external probe into the meter.
2. Press button until “
Unit will no
w display external probe temperature.
T2” appears in the display (Fig 5).
NOTE: If the external probe isn't plugged into the meter, “T2” will not
appear on display or any delta temperature.
DTH31-MAN
(Fig 5)
P. 2
MIN/MAX Function
1. Press “ “ button until “MIN” appears in display (Fig 6). Display
is now showing minimum humidity and temperature reading.
2. Press “ “ button again until “
MAX”appears in display (Fig 7).
Display is now showing maximum recorded humidity and
emperature readings.
t
. Press “ “ button until “MIN”or “MAX”disappear from display
3
to return to current readings.
4. Press “ “ button for more than 2 seconds to clear current
reading from memory.
*
(Fig 6)
(Fig 7)
NOTE: While checking MIN/MAX value for T2, ∆T, ∆DP, don’t replace the
probe or the error code will display. The error code will also appear if the
probe is not installed when checking MIN/MAX values.
∆T/DP and ∆DP/WB
T1 T2
∆T - is calculated by subtracting the T2 (Ex. temp.) from T1 (Air temp.).
∆DP - is calculated by subtracting the DP (dew point) from T2 (Ex. temp.).
(Fig 10)
Troubleshooting
If I See This I Should Check
Malfunction
Make sure the time of pressing “ “ - ON/OFF key is more
No display
Er 1
Er 2
Er 3
Er 4
Er 5
than 0.1 sec.
Check that the batteries are inserted correctly.
Replace batteries if needed
ator is displayed before display
Confirm batter
disappears. If yes, replace with new battery
Check if sleep mode is active. If yes, press “ +
button to disable auto po
Circuit error in RH measurement - Return instrument to UEi
for repair (see warranty)
Circuit error measuring internal temper
instrument to UEi for repair (see warranty)
Circuit error in self calibration channel - Return instrument to
UEi for repair (see warranty)
Internal temperature is out of range
External temperature is out of range
y indic
wer off function
HOLD”
ature - Return
1. Press “ “ button until ∆T appears in display (Fig 8).
2. Press “ “ button until ∆DP appears in display (Fig 9).
(Fig 8)
(Fig 9)
Low Battery
A battery symbol will display in the upper right corner when the battery
is low. Inaccurate readings will result from low batteries (Fig 10).
1. Open the battery cover on the back of instrument.
2. Remove the expired batteries.
3. Insert two new AAA V batteries.
Note: Dry bulb temperature is air (internal) temperature. Dew point
and wet bulb are calculated from internal temperature and humidity.
Specifications
Temperature
ange
ature r
emper
T
H%
R
Wet bulb -69 to 122˚F (-21.6 to 49.9˚C)
w point
De
External temper
Accuracy
H%
R
emper
T
General
Response time
Size
Cable length 45 5/8”
Probe (w/handle)
y
Batter
ature
ature
-4 to 122˚F (-20 to +50˚C)
00% R
0 to 1
-90.4 to 1
8˚F (-2
5
-4 to 1
3% at 77˚F (25˚C)
±
1˚F (0.6˚C)
±
60 seconds t
1” (H) x 1 7/8” (W) x 7” (L)
7 7/8”
.5V A
2 x 1
Standar
d & Optional Accessories
H
2˚F (-68 to 49.9˚C)
2
0˚C)
0 to 7
al
ypic
A batteries
A
Optional
External temperature probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ATT31
DTH31-MAN P. 3
DTH31
Digital Psychrometer
Limited Warranty
The DTH31 is warranted to be free from defects in materials and workmanship for a period of
one year from the date of purchase. If within the warranty period your instrument should
become inoperative from such defects, the unit will be repaired or replaced at UEi’s option.
This warranty covers normal use and does not cover damage which occurs in shipment or
failure which results from alteration, tampering, accident, misuse, abuse, neglect or improper
maintenance. Batteries and consequential damage resulting from failed batteries are not
covered by warranty.
Any implied warranties, including but not limited to implied warranties of merchantability
and fitness for a particular purpose, are limited to the express warranty. UEi shall not be
liable for loss of use of the instrument or other incidental or consequential damages,
expenses, or economic loss, or for any claim or claims for such damage, expenses or
economic loss. A purchase receipt or other proof of original purchase date will be required
before warranty repairs will be rendered. Instruments out of warranty will be repaired (when
repairable) for a service charge. Return the unit postage paid and insured to:
1-800-547-5740 • FAX: (503) 643-6322
www.ueitest.com • Email: info@ueitest.com
This warranty gives you specific legal rights. You may also have other rights which vary from
state to state.
PLEASE
RECYCLE
Copyright © 2007 UEi
DTH31-MAN 1/07
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