24
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Step 5. FIELd WIRING
Figure 44 - Wiring Diagram - Millivolt
Gas Valves
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 appliance
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 44)
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*, Thermostat,
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
thermostat, 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.
TP-TH
TP
TH
APPLIANCE- MOUNTED
ON/OFF SWITCH
(OPTIONAL)
BK/W(1)
BK/W(1)
WALL-MOUNTED ON/OFF SWITCH (OPTIONAL)
THERMOSTAT (OPTIONAL)
JUNCTION BOX
BLAC
K
W
GR
120
V
AC
WALL MOUNTED CONFIGURATION FOR FAN SWITCH (OPTIONAL)
BK
R
THERMOPILE
GAS VALVE
FAN
(OPTIONAL)
Figure 45 - Wiring Diagram - Electronic Gas Valves
P/N 580491-01
JUNCTION BOX
120V AC
REMOTE RECEIVER
ON/OFF SWITCH
WALL SWITCH
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
OPTIONAL 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
B. Electronic Wiring
(Figures 45 & 46)
One of the following optional controls also may
be used: ON/OFF Wall Switch, Thermostat,
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,
Page 11
).
3
. Remove the cover plate knockout; then
feed the power supply wire through the
knockout opening and into the unit junction
box.
4
.
See
Figures 45 & 46
. 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.
CAUTION
In millivolt systems, do NOT connect
a Wall Switch to a 120V power supply.
