Reference - Model IG
(4:1 Modulation)
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| 23 | 25 |
| 11 |
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| 20 | 21 |
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| 12 22 24 | 5 | 18 |
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26 |
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| 13 | 14 |
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1 | 7 | 8 |
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15 |
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| 19 |
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note
This is a typical blower control center, the control center in your unit may be different. Reference the ladder diagram on the inside of the control center door for a unit specific wiring diagram.
1.Supply Motor Starter - 24 volt magnetic contacts for starting supply motor.
2.Supply Overload - Provides electronic overload protection to supply motor.
3.Low Voltage Transformer - Provides low voltage to fan/heat/cooling enable controls, modulating furnace controls and optional evaporative cooling controls.
4.Control Terminal Block - Provides wiring access to controls.
5.Fan Relay - Allows power to pass to energize motor starter.
6.Control Terminal Block - Provides wiring access to fan/heat/cooling enable controls.
7.Auxiliary Contact (Optional) - Provides one normally closed and one normally open contact for other equipment.
8.Exhaust Motor Starter (Optional) - 24 volt magnetic contacts for starting exhaust motor.
9.Exhaust Overload (Optional) - Provides electronic overload protection to exhaust motor.
10.Exhaust Fuses (Optional) - Provides proper fusing for exhaust fan motor(s).
11.Building Freeze Protection Timer (Optional) - Prevents the discharge of cold air into the building.
12.Heat Relay - Allows power to pass to heating controls.
13.Low Voltage Transformer - Provides low voltage to the ignition controller.
14.Heating Terminal Block - Provides wiring access to heating controls.
15.Inlet Air Sensor (Optional) - Outdoor air stat that automatically controls the heating and/or cooling based on outdoor air temperature.
16.Modulation Controller - Provides 4:1 modulating turndown control of the furnace.
17.Amplifier - Controls the modulating valve based on the input from the modulation controller settings and the discharge air sensor.
18.Airflow Switch - Monitors the airflow inside the heat exchanger.
19.Ignition Controller - Controls the ignition of the furnace. Maintains safe operation of the furnace.
20.Modulation Controller (Optional) - Provides proper fusing to modulation controller.
21.Transformer Fuse (Optional) - Provides proper fusing to low voltage transformer.
22.Cooling Relay (Optional) - Allows power to pass to cooling controls.
23.Reset Timer (Optional) - Resets cooling system to run a time interval.
24.Auto Drain Relay (Optional) - Assures supply pump does not operate during drain interval. Allows pump to operate in cooling mode.
25.Cooling Timer (Optional) - Allows for automatic draining of the evaporative cooling system based on time schedule.
26.Dirty Filter Switch (Optional) - Monitors filter pressure drop. Turns on indicating light when pressure drop is above field adjustable set point.
Modulating
Gas Pressure Gas Valve
Test Port
Manifold |
| 3/4 inch |
| Gas Supply | |
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| Staged | Connection |
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| Gas Valve |
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66 Model IG / IGX
®
