York SUNLINE MagnaDRY DR180 Installation Manual

Also see for SUNLINE MagnaDRY DR 180: Submittal data sheet Installation manual

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York SUNLINE MagnaDRY DR180 Installation Manual Manual pdf 61 page image

127915-YIM-A-0405Unitary Products Group 61GAS HEATING SEQUENCE OF OPERATIONSThe following sequence describes the operation of thegas heat section.When the thermostat calls for the first stage of heating,the low-voltage control circuit from "R" to "W1" and "G"is completed, thru the UCB. The heat relay "RW1" isenergized. The "RW1-2" contacts close energizing thedraft motor control. The draft motor control contactsclose and start the draft motor. As the speed of thedraft motor reaches approximately 2500 RPM, the cen-trifugal switch contact, located on the end of the draftmotor shaft, closes to power the first stage ignitionmodule "IC1", thru the "RW1-1 contacts.Ignition module "IC1" will immediately start the firststage igniter sparking and will open the redundantvalve located inside the first stage main gas valve"GV1" to allow a flow of gas to only the first stage carry-over tube. Only after the pilot flame has been ignitedand the presence of pilot flame detected at the "IC1" bya signal sent back through the flame sensor is sparkingterminated and the first stage main gas valve opened.Gas flows into each of the main burners and is ignitedfrom the carryover tube flame.After completing the specified fan on delay for heating,the UCB will energize the blower motor.If "IC1" fails to detect a pilot flame, it will continue to tryfor a maximum of 85 seconds to ignite the pilot tube. Ifthe pilot flame is not detected, then "IC1" will lock outfirst stage furnace operation for five minutes or until24V power is removed from the module either at theunit or by resetting the room thermostat.When the thermostat calls for the second stage ofheating, the low-voltage control circuit from "R" to "W2"is completed, thru the UCB. Heat relay "RW2" is ener-gized. The "RW2-1" contact is closed energizing thesecond stage ignition module "IC2". "IC2" will immedi-ately start the second stage igniter sparking and willopen the redundant valve located inside the secondstage main gas valve "GV2" to allow a flow of gas tothe second stage carryover tube. Only after the pilotflame has been ignited and the presence of pilot flamedetected at "IC2" by a signal sent back through theflame sensor is sparking terminated and the main gasvalve opened.Gas flows into each of the second stage main burnersand is ignited from the carryover tube flame.If "IC2" fails to detect a pilot flame, it will continue to tryfor a maximum of 85 seconds to ignite the pilot tube. Ifthe pilot flame is not detected, then "IC2" will lock outfirst stage furnace operation for five minutes or until24V power is removed from the module either at theunit or by resetting the room thermostat.NOTE: That the second stage furnace can operateeven if first stage has locked out.When the thermostat satisfies de-energizing the"RW2"and "RW1", thus opening all gas valves. Theblower motor will continue to run after the furnace isshut down until the specified fan off delay for heatinghas been satisfied. The UCB will de-energize theblower motor.When the thermostat calls for the first stage of heating,the low-voltage control circuit from "R" to "W1" is com-pleted. A call for heat passes through the UCB to theignition control board (ICB). The UCB monitors the"W1" call and acts upon any call for heat. Once voltagehas been sensed at “W1”, the UCB will initiate the fanon delay for heating, energizing the indoor blower afterthe specified delay has elapsed.TABLE 29: ELECTRIC HEAT ANTICIPATORSETPOINTSHEATERKW VOLTAGE SETTING, AMPSTH1 TH218208/230-3-600.29 -36 0.29 0.2954 0.29 0.5872 0.29 0.5818460-3-600.29 -36 0.29 0.2954 0.29 0.2972 0.29 0.2918575-3-600.29 -36 0.29 0.2954 0.29 0.2972 0.29 0.29FIGURE 23 - GAS VALVE PIPINGGASVALVEGAS MAINMAIN VALVETO MAINBURNERREDUNDANTVALVETO PILOT BURNER