11
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
B-VENT GAS FIREPLACES (MPB33/35/40/45) • INSTALLATION INSTRUCTIONS
STEP 4. FIELD WIRING
CAUTION
The ground supply lead must be
connected to the wire attached to the
green ground screw located on the
outlet box
(see wiring diagrams)
.
Failure to do so will result in a
potential safety hazard. The appli-
ance must be electrically grounded
in accordance with local codes or,
in the absence of local codes, the
National Electrical Code, ANSI/
NFPA 70 - latest edition (in Canada,
the current CSA C22.1 Canadian
Electrical Code).
CAUTION: Label all wires prior to discon-
nection when servicing controls. Wiring
errors can cause improper and dangerous
operation.
ATTENTION: Au moment de l’entretien
des commandes, étiquetez tous les fils
avant de les débrancher. Des erreurs de
cáblage peuvent entraîner un fonc-
tionnement inadéquat et dangereux.
Verify proper operation after servicing.
S’assurer que l’appareil fonctionne adé-
quatement une fois l'entretien terminé.
Refer to Section A for millivolt appliances
and Section B for electronic appliances. The
gas valve is set in place and pre-wired at the
factory on both models.
A. Millivolt Wiring
(see Figure 18)
Millivolt units are not provided with any factory-
installed controls; therefore, one of the optional
control switches is required to operate the unit
(ON/OFF Wall Switch, Unit-Mountable ON/OFF
Switch*, Remote Control). See the fireplace
Care and Operation Instructions for details.
[*If using a Unit-Mountable ON/OFF Rocker
Switch with an optional Style View Door,
mount the Rocker Switch on the door instead
of the unit.]
1
. If installing an ON/OFF wall switch or
receiver, mount it in a convenient location
on a wall near the fireplace.
2
. Wire the control switch within the millivolt
control circuit using the 15 feet of 2
conductor wire supplied with the unit.
NOTE:
The supplied 15 feet of 2 conductor wire
has one end of each conductor connected to
the gas valve circuit and the other end of each
conductor placed loose inside the bottom
compartment.
P/N 580491-01
JUNCTION BOX
120V AC
REMOTE RECEIVER
ON/OFF SWITCH
WALL SWITCH
SAFETY LIMIT SWITCH
B-VENT MODELS ONLY
AC/DC
POWER
ADAPTOR
HOT
NEUTRAL
OPTIONAL
GROUND
BATTERY HOLDER
DFC WIRE HARNESS
SPARK WIRE CABLE
PILOT GROUND WIRE
PILOT
SENSOR
CABLE
HOOD
IGNITER ROD
FLAME SENSOR
PILOT TUBE
CPI
SWITCH
OFF (O) = INTERMITTENT PILOT MODE
ON (-) = STANDING PILOT MODE
PROFLAME DFC BOARD
PROFLAME VALVE
ELECTRONIC PILOT ASSEMBLY
B = BLACK
BR = BROWN
GY = GRAY
PU = PURPLE
R = RED
BL = BLUE
G = GREEN
O = ORANGE
W = WHITE
Y = YELLOW
WIRING COLOR CODE
B
B
B
R
R
W
W
B
B
B
B
BL
BL
G
G
O
Y
Y
R
R
Y
W
G
G
O
SCHEMATIC REPRESENTATION ONLY
Figure 17 - SIT Milivolt Wiring
Diagram
If any of the original wire as supplied must be replaced,
it must be replaced with Type AWM105
°
C – 18 GA. wire.
Thermopile
H T
P T
H T
P T
*TWIST WIRES “ A ” AND “ B ” TOGETHER TO OPERATE UNIT
SOLELY BY MANIPULATING THE GAS VALVE CONTROL KNOB;
OR CONNECT WIRES TO OPTIONAL ON/OFF SWITCH OR WALL
SWITCH OR REMOTE CONTROL RECEIVER TO OPERATE UNIT.
*OPTIONAL ON/OFF SWITCH,
WALL SWITCH, OR REMOTE
CONTROL RECEIVER
A
B
H C
T I
W S
T I
M I
L
WT
BK
BK
BK
Schematic Representation Only
Figure 18 - Optional J-Box/Outlet Box
(Left Side Shown)
See
Figure 12
on
Page 9
for Optional Electrical Inlet
Knockout Location.
* Field-Provided
Junction Box and
Duplex Receptacle
* Narrow (2-1/8" Wide)
J-Box Required
CAUTION: ENSURE THAT WIRES ARE POSI-
TIONED AWAY FROM HOT SURFACES AND
SHARP EDGES.
Figure 16 - Wiring Diagram - Electronic Gas Valves
B. Electronic Wiring
(see Figure 18)
One of the following optional controls also
may be used: ON/OFF Wall Switch, Remote
Control (see fireplace Care and Operation
Instructions for details.).
NOTE:
Electronic models must be connected
to the main power supply.
1
. Route a 3-wire 120Vac 60Hz 1ph power
supply to the appliance junction box.
2
. Remove the electrical inlet cover plate from
the side of the unit by removing the plate’s
securing screws (see
Figure 12 on
Page
9
).
3
. Remove the cover plate knockout; then
feed the power supply wire through
the knockout opening and into the unit
junction box.
4
. See
Figure 18
. Connect the
black power
supply wire to the lower outlet’s red
pigtail lead
.
Connect the
white power supply wire to
the outlet’s common terminal
.
5
. Connect the
ground supply wire to the
pigtail lead attached to the outlet’s green
ground screw.
NOTE:
Remote receiver should be located in the
wall, or if installed in the control compartment,
pulled all the way forward and completely to the
left or right against the corner posts.
CAUTION
In millivolt systems, do not connect
optional control switch to 120 V power
supply.