2
RH25
‐
EU
‐
EN
v1.0
5/13
Introduction
Thank
you
for
selecting
the
Extech
Instruments
Model
RH25
Heat
Index
Psychrometer.
The
RH25
measures
Temperature
and
Relative
Humidity
(using
precision
capacitance
RH
sensor).
The
RH25
also
calculates
and
displays
Heat
Index,
Dew
Point,
Wet
Bulb,
and
Wet
Bulb
Globe
temperatures.
The
High
Temperature
Alarm
feature
alerts
the
user
when
Heat
Index
or
Wet
Bulb
Globe
levels
exceed
user
‐
preset
limits.
Data
Hold
and
MIN/MAX/AVG
memory
utilities
make
it
easier
to
recall
important
data.
This
device
is
shipped
fully
tested
and
calibrated
and,
with
proper
use,
will
provide
years
of
reliable
service.
Please
visit
our
website
(www.extech.com)
to
check
for
the
latest
version
of
this
User
Guide,
Product
Updates,
and
Customer
Support.
Description
Meter
1.
Sensor
area
2.
Display
area
(LCD)
3.
POWER
button
4.
HOLD
button
5.
MODE
button
6.
Battery
compartment
on
rear
of
instrument
Display
TEMP
Temperature
AIR
T
Air
Temperature
RH
Relative
Humidity
HI
Heat
Index
DP
Dew
Point
temperature
WB
Wet
Bulb
temperature
WB/HI
Wet
Bulb
Globe
temperature
MAX
Maximum
reading
memory
MIN
Minimum
reading
memory
AVG
Average
reading
memory
HOLD
Data
Hold
(freezes
display)
BAT
Low
Battery
symbol
%
Percent
units
for
RH
readings
o
Degrees
symbol
for
temperature
units
E
Used
to
display
temperature
units
C
or
F
