Extech Instruments RH25 User Manual

4RH25‐EU‐ENv1.05/13
Selecting
o
C/
o
Funitsofmeasure
WiththemeterOFF,pressandholdthePOWERandMODEbuttonssimultaneouslyuntiltheunit
of measure appears on the lower right corner of the LCD. Use the MODE button to select the
desiredunit ofmeasure(
o
Cor
o
F).PressPOWERtwice tosteppastthealarm settingsuntilthe
normalmeasurementmodeisdisplayed.

HighAlarmforHeatIndexandWetBulbGlobetemperature
1. WiththemeterOFF,pressand holdthePOWERandMODEbuttonssimultaneouslyuntilthe
temperatureunit‘C’ or‘F’appearsonthe  lowerrightcorner oftheLCD(ifdesired,usethe
MODEbuttontoselectthedesiredunitofmeasure).
2. PressthePOWERbuttontostepto
theHeatIndex(HI)AlarmON/OFFdisplay.
3. UsetheMODEbuttontoselectON(A‐on)orOFF(A‐oF);seedisplayexamplesbelow:
4. PressPOWERtosteptotheHeatIndextemperatureAlarmlimitvalue.Seeexamplebelow:

5. PresstheMODEbutton momentarilytochangethevalueinsmallsteps.Pressandholdthe
MODEbuttontoscrollquickly.
6. When the desired Heat Temperature alarm limit is displayed, press the POWER button to
continuetotheWetBulbGlobetemperatureAlarmprogrammingscreens.
7. Repeat steps
3‐6 to program the Wet Bulb Globe temperature ON/OFF and Alarm limits.
UsethePOWERbuttonwhendonetostepbacktothenormaloperatingmode.
8. Thedefaultsettings are27.8
o
C(82.0
o
F)forHeat Indextemperaturealarmlimitsand 28.0
o
C
(82.4
o
F)forWetBulbGlobetemperaturealarmlimits
9. When either alarm limit is exceeded, the meter continuously beeps. To determine which
alarm is sounding, check the HI (Heat Index) and WB/HI (Wet Bulb Globe) temperature
displaystoseewhichunitofmeasureisblinking,thatwillindicatethetrippedalarm.

10. TosilenceanalarmtheusermusteitherswitchthealarmOFForchangeitsalarmlimitvalue.


ErrorMessageDisplays
E‐2:HumiditySensorfailure.Replaceunit.
E‐3:TemperatureSensorfailure.Replaceunit.
E‐4:Temperatureover‐range;E‐5:Temperatureunder‐range
E‐6:Hardwarefailure.Replaceunit

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.)