EngA DJM3

A DJM3
IOM-17 14 of 27 Mar 99 R3
OPERATION

DAY/NIGHTOPERATION
TheDJM3supportsavarietyoffan,damper,andtemperaturecontroloperatingschemes.Theexact
operationdependsonthestatusofterminals“FS,HS”,and“K”.Nightoperationisnotsuitablefor
100%make‐upairapplications,duetotheequipmenthavingtoopenoutsideairdampersandheat
outsideair.TooperateinNightmode,aroomthermostatormake/breakresetmustbeused.
TABLE12
TerminalStatus
Blower
Operation
Damper
Operation
ControlSource
Control
Mode
HS FS K
XXX
XXX
Off
On
Off
Off
Off
Constant
Off
Powered
N/A
Discharge/Room/BMS
Off
Day
Off
On
On
XXX
Off
On
On
On
On
Off
Intermittent
Constant
Off
Off
Off
N/A
Room
Dischargew/Room
Reset
Off
Night
Night
XXX=Switch(SW.)canbe"ON"or"OFF"

FANCONTROL
Indaymode,thesupplyairfanshouldruncontinuously(unlessjuststartingthemorningwarm‐upor
trippedonlowlimit.).Forsupplyfanoperation,thedischargesensormustbeoperatingcorrectlyasit
isalsousedasthelowlimitsensor.Ifthedischargesensorresistanceistoohigh(oropencircuit),the
DJM3perceivesalowlimitfaultandlocksoffDJM3.

DAMPERCONTROL
Theinletdamperactuator(s)isenabledthroughoutputterminalDM2.TheDJM3hasadelayedsupply
blowerstarttoallowtimeforthedamperstoopen.

BURNERCONTROL
Burnerisenabledwhenavalidheatcallismadeandterminal“HS”ispowered.TheDJM3willentera
heatexchangerpurgecycle.Whenthepurgecycleiscomplete,theDJM3willruncombustionblower
atlight‐offspeedandenabletheignitioncontroltostartthepilot.Whentheignitioncontrolproves
pilotlight‐offitwillenablethemaingasvalve.OncethemainflameisestablishedandtheDJM3
receivesafeedbacksignaltoterminalsVFB24orVFB120andVNthecontrolwillmodulatethegas
valveandcombustionblowertosatisfytheheatcall.IftheDJM3doesnotreceivethefeedbacksignal
thealarmcontact,terminal“AL”,willbeactivated.

WhenheatcallissatisfiedtheDJM3willcycleofftheburner.Thecombustionblowerwillcontinueto
runforseveralminutesafterheatcallisopentomaintainpurgeandcoolofftheburnerandheat
exchanger.
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