Reference
Typical Control Center Layout
7
14
10
9
15
11
12
13
4 
3
5 8
1 
2
6
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 enable controls.
4.Control Terminal Block — provides wiring access to controls.
5.Fan Relay — allows power to pass to energize motor starter.
6.Auxiliary Contact (optional) — provides one normally closed and one normally open contact for other equipment.
7.Dirty Filter Switch (optional) — monitors filter pressure drop, turns on indicating light when pressure drop is above field adjustable set point.
8.Heat Relay — allows power to pass to heating controls.
9.Heating Terminal Block — provides wiring access to heating controls.
10.Flame Safeguard — monitors flame, shuts down unit when unsafe conditions are detected.
11.High Limit — prevents unit from discharging air above a set point.
12.Low Voltage Transformer — reduces voltage to Maxitrol system.
13.Amplifier — controls modulating valve, assures the desired temperature is delivered.
14.Spark Generator — provides spark to ignite the burner.
15.Transformer — provides voltage to Flame Safeguard.
Dirty Filter Switch
Common
Normally Open
Normally Closed
CCW to decrease trip point
CW to increase trip point
Negative Pressure after the filters
Positive Pressure before the filters
28 DGX Industrial Space Heating
®