HONEYWELL SV9541M "SMART VALVE" Sequence of Operation
I POWERAPPLIEDTOAPPUANCE l
ITHERMOSTAT CALLS FOR HEAT

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IPRESSURESWITCHESPROVEDOPEN?
i
ICOMBUSTIONBLOWERENERGIZED
I
PRESSURESWITCHESCLOSEDWITHIN30SEC-
ONDS?
3SECONDPRE-PURGE
PILOTVALVEOPENS:
IGNITORPOWERED(1)
PILOTLIGHTSANDFLAME IS SENSED I_uI
DURING90SECONDTRAILFOR
IGNITION?
_I YES
MAINVALVE OPENS,
HEATINGFAN "ON" DELAY BEGINS
AFTERDELAY:CIRCULATINGBLOWERSTARTS I
I
FLAME SENSE LOST?
THERMOSTAT CALL FOR HEAT ENDS
_ NOIP,LOTANDMAINVALVECLOSE I
COMBUSTIONBLOWERDE- ENERGIZEDAFTER30
SECONDPOSTPURGE
ICIRCHLAT_NGBLOWEROFFAFTERDELAY I/WA.FORNEXTCALLFORHEAT I
Ll
I
WAITFORPRESSURESWITCHESTOOPEN
_1_ COMBUSTIONBLOWERDE-ENERGIZED _[ FIVEMINUTEWAITPERIOD
I
LTHREE SECOND FLAMEFAILURERECYCLE DELAY
PILOTVALVECLOSES;
PILOTIGNITOROFF
YES
.[ PILOTANDMAINVALVECLOSE
FLAME SENSE LOST MORE THAN FIVE I
TIMESINTHISCALL FOR HEAT? J--
NO
YES

J

ICIRCULATINGBLOWEROFF AFTER DELAY I
+
COMBUSTIONAIRBLOWEROFF AFTERPOST
PURGE
(1)Ignitor "ON" for first 30seconds of trial for ignition,then"OFF" for next 30seconds. Ifthe pilot has
notlit,it turns back"ON" for the final30seconds. Thepilot valve remainsenergizedduringtheentire
90second trialfor ignition.
NOTE:If mainlimit string opensandtakes longerthan2minutesto close, system goes intoIhourwait
period.
440O1102004 [_