Greenheck Fan 470656 Fan User Manual


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Sequence of Operation
2:1 Modulation Sequence
1. Exhaust Fan Contact (S1) Manually Closed
(optional)
• PowerpassesthroughN.C.contactonexhaustfan
overload (ST2 OL), which is closed if exhaust fan
(M2) has not overloaded
• Powerpassestoexhaustfanstarter(ST2)
• N.O.contactonexhaustfanstarter(ST2)is
energized and closed
• Powerpassestoandenergizesexhaustfan(M2)
2. Supply Fan Contact (S2) Manually Closed
• PowerpassesthroughN.C.eld-suppliedre
contact (FSC)
• PowerpassesthroughoptionalN.O.contacton
exhaust fan starter (ST2), which is closed when the
optional exhaust starter (ST2) is activated
• PowerpassesthroughN.C.contactonsupply
starter overload (ST1 OL), which is closed if the
supply fan has not overloaded
• PowerpassesthroughN.C.contactonoptional
freeze protection timer (RT4), which is closed if the
temperature has remained above the set point
• Powerpassestoandenergizesoptionalinlet
damper (D1), which opens
• Powerpassesthroughoptionaldamperlimitswitch
(DL1), which is energized and closed if the optional
inlet damper is open. It may take several minutes
for the damper to fully open and for the damper
limit switch to close
• Powerpassestoandenergizesfanrelay(RF)
• PowerpassesthroughN.O.contactonfanrelay
(RF), which is closed once the fan relay (RF) is
activated
• Powerpassestoandenergizesstarterrelay(ST1)
• N.O.contactonsupplyfanstarter(ST1)is
energized and closed
• Supplyfan(M1)starts
3. Heat Contact (S4) Manually Closed
• PowerpassesthroughN.O.contactonfanrelay
(RF), which is energized and closed if the supply
fan (M1) is on
• PowerpassesthroughtheN.C.contactonoptional
inlet air sensor (TS4), which is closed if inlet air
temperature is below set point
• Powerpassestoandenergizestheheatrelay(RH)
• PowerpassestoN.C.contactonhightemperature
limit control (HLC1), which remains closed if it has
not been tripped
• N.O.contactonheatrelay(RH)closes
• 24VACissuppliedtoignitioncontroller(IC1)and
amplifier (AMP)
• Ifthedischargeairsensor(TS2)readingisless
than the temperature selector (TS3) setting, the
amplifier (AMP) sends a call for heating to the
ignition controller (IC1)
4. Ignition Controller (IC1) Sequence of Operation
• TheN.O.contactonairprovingswitch(PS2)isopen
• Theignitioncontroller(IC1)energizesthe
combustion blower relay (CR)
• N.O.contactoncombustionblowerrelay(CR)
closes
• Powerpassestoandenergizesthecombustion
blower (CM)
• TheN.O.contactonairprovingswitch(PS2)closes
• Theignitioncontroller(IC1)beginsa15second
pre-purge
• Thehighrerelay(RT3)isenergizedandtheN.O.
contact on high fire relay (RT3) closes
• Themaingasvalve(MV)fullyopens(100%)andthe
modulating gas valve (MOD) opens to high fire
• Igniterbeginssparking
• 10secondtrialforignitionbegins
• Thefurnacewilllightathighre(100%)
• Whentheameisdetected,theigniterstops
sparking
• Thefurnacewillremainathighre(100%)forat
least 10 seconds
• Highrecontact(RT3)willopen
• Furnacemodulatestomaintainthetemperature
selector (TS3) set point
5. High Fire – Low Fire Sequence of Operation
• Thefurnacelightsatandremainsathighre
(100%) for 10 seconds
• Ifthedischargetemperaturesensor(TS2)reading
is above the temperature selector (TS3) set point,
and furnace is not at low fire, the amplifier will
adjust the modulating gas valve (MOD) down until
the discharge temperature sensor (TS2) reading
equals the temperature selector (TS3) setting
• Ifthedischargetemperaturesensor(TS2)reading
is below the temperature selector (TS3) set point,
and the furnace is not at high fire, the amplifier will
adjust the modulating gas valve (MOD) up until the
discharge temperature sensor (TS2) reading equals
the temperature selector (TS3) setting
• Ifthefurnaceisatlowreandthedischarge
temperature sensor (TS2) reading is above the
temperature selector (TS3) set point, the amplifier
will end the call for heat and the ignition controller
(IC1) will shut down the furnace
6. Optional Evaporative Cooling Contact (S4)
Closed*
• N.O.contactonfanrelay(RF)isenergizedand
closed
• PowerpassesthroughN.O.contactonoptional
inlet air sensor (TS4), which is energized and
closed if the inlet air temperature is above the set
point
• Powerpassestoandenergizescoolrelay(RC)
®
Model IG / IGX Make-Up Air
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