EngA DJM3

A DJM3
IOM-17 9 of 27 Mar 99 R3
MULTIMETERTESTPOINTS
TheDJM3hasreadoutterminalsformeasuringthedischargesensortemperatureandthecalculated
dischargesetpoint.These3testpointsarelocatedneartheMandQterminals.
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MeasurementsaremadeusingaVdcmultimeterusingascaleof1Vdc=10°C.Forexample,areading
of2.1Vdc=21°C(or70°F).RefertothetablebelowforCelsiustoFahrenheitconversion.
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TABLE5
VoltageReading(Vdc) °C °F
1.0 10 50
1.5 15 59
2.0 20 68
2.5 25 77
3.0 30 86
3.5 35 95
4.0 40 104
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SYSTEMTIMINGS
Thetimeslistedaregeneral,andmaybeaffectedbyexternaltimedelaydevices.
TABLE6
Pre‐purge 45seconds
Postpurge 4minutes(daymode)1minute(nightmode)
Fandelay 30seconds
Warmuptime 30seconds
Cooldowntime 60seconds
Lowlimitbypass 5minutes
FlameFailure 90seconds
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TEMPERATURECONTROL
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CALCULATEDSETPOINT(SPC)
TheDJM3isdesignedtobeadischargeairtemperaturecontrol.Thebasedischargeairtemperature
setpointistypicallysetfromthecontrolpotlocatedonthefaceoftheDJM3.Thebasedischargeair
temperatureisnormallymodifiedfromaremotesignaltomaintainthedesiredtemperatureofthe
suppliedspace.Thisiscalledreset.TheDJM3dischargesetpointcanberesetfromavarietyofsources
suchasambientairtemperature,modulatingorstagedroomthermostats,returnairtemperature,ora
BMSsignal(0‐10Vdcor4‐20mA).
Withoutanytemperatureresetmethodthebasesetpoint(eitherfacemountedorremotemounted)is
thecalculatedsetpointthattheDJM3willattempttomaintainthedischargetemperatureat.
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SetpointCalculation(SPC)=DischargeSetpoint+Reset
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