18
Boss DF Construction Heaters
Control Box Components
FIG. 10
E G
D
F
A. Ignition Control
The ignition control is an electronic circuit board
that starts the fan motor, and monitors burner fl ame
presence through the ignitor and earth ground. (A
good, secure earth ground is required for continued
operation. If the earth ground is missing or poorly
connected, the ignition control will not be able to
prove fl ame, and it will eventually shut the heater
down)
Refer to the following and Fig. 11 to understand the
ignition control's terminal designators when doing
voltage checks on the ignition control.
MV: 120 VAC from ignition control to gas solenoid
valve.
PSI: 120 VAC from air proving switch to ignition
control.
IND: 120 VAC from ignition control to motor relay.
The relay then sends the power to the motor.
L1: 120 VAC incoming power supply to ignition
control.
R: No terminal.
PSO: 120 VAC from ignition control to air proving
switch.
W: No terminal.
FS: No terminal.
GND: Power cord and chassis ground.
NEU 3: Neutral for volt meter.
NEU 2: Neutral for relay.
NEU 1: Neutral for power cord, gas control valve,
and motor.
Owner's Manual • Boss DF
A
C
H
B
A
Ignition Control
B
Air Pressure Switch
C
Relay
D
Selector Switch
E
Manual Reset Circuit Breaker
F
Voltage Meter
G
Red Status Light
H
Thermostat