UHD S
TANDARD
D
UCT
F
URNACE
I
NSTALLATION
O
PERATION
AND
S
ERVICE
M
ANUAL
18
9.3 Internal Wiring Diagram
IMPORTANT:
For field wiring into service junction box, or if any of the original wire supplied with the heater
must be replaced, it must be replaced with wiring material having a temperature rating of at least 105 °C
(221 °F) and 600 V. For supply connections, use No. 14 AWG or larger wires.
BLUE
BLACK
ORANGE
ORANGE
YELLOW
BROWN
WHITE
WHITE
L2 L1
ORANGE
ORANGE
BLACK
BLACK
GREEN
WHITE
BLUE
BLACK
GREEN
BLUE
GREEN
YELLOW
24 V
AC
HOT
GROUND
FLAME
BLACK
BLACK
6
3
4
2
1
4
5
3
1
SENSE
ELECTRODE
LIMIT SWITCH
PRESSURE SWITCH
GAS VALVE
IGNITION MODULE
TRANSFORMER
LIMIT SWITCH (UHD 300, 350, 400 ONLY)
MANUAL RESET LIMIT SWITCH (RESIDENTAL UNITS ONLY)
THERMOSTAT INPUT: FIELD SUPPLIED
R
=
24 VAC TO THERMOSTAT (RED)
G
=
MANUAL FAN INPUT FROM THERMOSTAT (GREEN)
W
=
HEAT DEMAND INPUT FROM THERMOSTAT (WHITE)
C
=
COMMON GROUND TO THERMOSTAT
FLUE
BLOWER
R
G
W
C
ACC
L1
CMB BLOWER
5
