CIRCULATOR BLOWER FAN TIMING ADJUSTMENT
NOTE: Items in this section refer to the air circulator blower fan NOT to the induced draft blower. The induced draft blower timing sequence is not adjustable. The circulator blower fan timing is adjustable only on models with optional “heating fan OFF delay” adjustment pins or switches. It is NOT adjustable in any other circumstances.
As shipped, the circulator blower fan will remain on for 150 seconds after the gas valve closes. When a call for cooling occurs, the circu- lator fan comes on and remains on for 45 seconds after the call for cooling ends. During normal heating operation, the circulator fan will come on approximately 34 seconds after the gas valve opens.
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Switch viewed in an upflow installation.
Adjustment Switch
SETTING FURNACE OPERATING MODE
This furnace is designed to operate with either a single gas input rate or with two distinct gas input rates. The Mode DIP switch is used to select the single gas input rate or two distinct input rates.
Setting the Mode switch to “1 STG” forces the furnace to operate at the furnace’s highest input rate only. Operation is as described under Sequence of Operation (Integrated Ignition Control) – Mode DIP Switch is set to “1 STG” position.
Setting the Mode switch to “2 STG” allows the furnace to operate at the furnace’s highest input AND at an input rate that is 75% of the highest input rate. For this mode of operation, the furnace oper- ates at the low input rate for a
The time period is determined by the 2nd Stg Dly DIP switch. Setting the 2nd Stg Dly DIP switch to 5 minutes fixes the delay period at 5 minutes. Setting the 2nd Stg Dly DIP switch to Auto enables an algorithm that calculates a delay period based on the heating cycle time and the total cycle time. The delay period can range from 1 minute to 12 minutes.
NOTE: The ACSH, AMH, AMEH, GCH, GDH, GMH and GME hybrid furnaces require a single stage thermostat. These furnaces utilize a control board with single stage or two stage capability. The second stage feature is established by setting dip switch #2 on the board, either one stage or two stage. All of the second stage timing is then controlled by dipswitch 3 on the circuit board.
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XV. NORMAL SEQUENCE OF OPERATION
POWER UP
The normal power up sequence is as follows:
•115 VAC power applied to furnace.
•Integrated control module performs internal checks.
•Integrated control module LED will light.
•Integrated control module monitors safety circuits continuously.
•Furnace awaits call from thermostat.
HEATING MODE
(MODE DIP SWITCH IS SET TO “1 STG” POSITION)
The normal operational sequence in heating mode is as follows:
•R and W thermostat contacts close, initiating a call for heat.
•Integrated control module performs safety circuit checks.
•Induced draft blower is energized for 15 second
•Igniter warm up begins after 15 second prepurge expires.
•Low and high stage gas valves open at end of igniter warm up period, delivering gas to burners and establishing flame.
•Integrated control module monitors flame presence. Gas valve will remain open only if flame is detected.
•Circulator blower is energized on high heat speed following a fixed thirty second blower on delay. Electronic air cleaner terminals are energized with circulator blower.
•Furnace operates; integrated control module monitors safety circuits continuously.
•R and W thermostat contacts open, completing the call for heat.
•Gas valve closes, extinguishing flame.
•Induced draft blower is
•The circulator blower remains at high heat speed for thirty seconds. The circulator blower then switches to low heat speed for the remainder of the selected heat off delay period. For example, the selected heat off delay period is 150 seconds. The circulator blower operates at high heat for 30 seconds and at low speed for 150 - 30 = 120 seconds.
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