Extech Instruments RH25 User Manual

3RH25‐EU‐ENv1.05/13
Operation
Keypad
POWER:SwitchthemeterONorOFF;alsousedtoentertheMAX/MIN/AVGmemorymode.
HOLD:PresstoenterDataHold(readingfreezesondisplay).PressagaintoexitDataHold.
MODE: Press to step through the measurement modes: TEMP (Temperature), RH (Relative
Humidity),HI(HeatIndex),DP(DewPoint),(WB
(WetBulb),andHI/WB(WetBulbGlobe).
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Poweringthemeter
PressPOWERtoswitchmeterON.Themetershowsalldisplayiconsmomentarilyasitswitches
ONandthentheTEMPiconandthe temperaturereadingwilldisplay.Themeterwillalsoemita
chirpsoundasitswitchesON.
ToswitchthemeterOFF,pressandholdthePOWERbutton
foratleast2seconds.
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MAX/MIN/AVGMemory
WiththemeterpoweredON,pressPOWERbuttonmomentarily.TheMAXiconwillappearand
themeterwilldisplayonlythehighestreading.
PressPOWERagain;theMINiconwillappearandthemeterwillonlydisplaythelowestreading.
PressPOWERagain;theAVGiconwillappearandmeterwill
onlydisplaytheaveragereading.
PressPOWERagaintoexit(theMAX/MIN/AVGiconswillswitchOFF).
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DataHold
With the meter powered ON, press the HOLD button momentarily. The HOLD icon will appear
andthecurrentreadingwillfreezeonthedisplay.PressHOLDagaintoexit(theHOLDiconwill
switchOFF).
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AutomaticPowerOFF(Sleep)Mode
The meter switches OFF automatically after 15 minutes of inactivity. To defeat this feature
temporarily:WiththemeterswitchedOFF,presstheHOLDandPOWERbuttonssimultaneously
until the meter displays  the screen shown below. Now, the user must switch the meter OFF
manuallybypressing andholding thePOWER button
forat least2seconds.Notethat thenext
timethemeter’spoweriscycled,theAutoPowerOFFutilitywillagainbeactive.
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Extech Instruments RH25 Specifications

Measurements

air temperature range	-20 to 50 °C (-4 to 122 °F)
heat index range	-46 to 205 °C (-50.8 to 401 °F)
dew point range	-78 to 50 °C (-108.4 to 122 °F)
wet bulb range	-20 to 50 °C (-4 to 122 °F)
wet bulb globe range	-25 to 54.5 °C (-13 to 130 °F)
relative humidity range	0 to 99.9% RH

Accuracy

temperature accuracy	±0.6 °C (1 °F)
relative humidity accuracy	±3% RH @ 25 °C from 10 to 90% RH otherwise ±5% RH

Power

power supply	1 x CR2032 Lithium Battery

Weight and Dimensions

dimensions	140 x 35 x 18 mm (5.5 x 1.4 x 0.7")
weight	50 g (1.8 oz.)