Pre-Installation Steps; Typical Installation Sequence; Detailed Installation Steps; Step 1. Framing - Lennox MPDT33RNM Installation Instructions Manual

LENNOX HEARTH PRODUCTS • MERIT PLUS

PRE-INSTALLATION STEPS

The appliance is shipped with all gas controls
and components installed and pre-wired.
Before installing the appliance, follow these
steps:
1. Remove the shipping carton.
2. Remove the shipping pad, exposing the front
glass door.
3. Open the two spring latches securing the
glass door (under the firebox floor). Remove
the door by tilting it outward at the bottom
and lifting it up. Set the door aside, taking
care to protect it from inadvertent damage.
See Removing Glass Panels on Page 32.
5. Remove the log set from the firebox. Handle
logs carefully to prevent breakage.
6. Remove the embers and volcanic stone from
the control compartment.
10
DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
®

TYPICAL INSTALLATION SEQUENCE

The typical sequence of installation is
outlined below; however, each installation
is unique and may result in variations to the
steps described. See the pages referenced in
the following steps for detailed procedures.
Step 1. FRAMING (Page 10): Construct the
appliance framing. Position the appliance
within the framing and secure with nailing
brackets.
IMPORTANT! Bend up the appropriate
header spacing standoffs for the drywall/
finish material thickness to be used
(see Figure 11).
Bend up the outer pair for 1/2 in. materials
and the inner pair for 5/8 in. materials.
Bend out the appropriate nailing flanges for
the drywall/finish material to be used. Nailing
flanges are provided for flush framing, 1/2 in.
and 5/8 in. framing depths (see Figure 11).
Step 2. ROUTING GAS LINE (Page 12):
Route gas supply line to appliance location.
Step 3. PREPARING APPLIANCE VENT
COLLAR (MPD35/-40/-45 models with
combined top/rear vent) (Page 13).
Step 4. INSTALLING VENT SYSTEM
(Page 13): Install the vent system and
exterior termination.
Step 5. FIELD WIRING (Page 25).
a. Millivolt Appliances—Install the
operating control switch (not factory
provided). If installing the optional forced
air circulating blower, bring in electrical
service line.
b. Electronic Appliances—Field wire and
install operating control switch.
Step 6. WIRING—OPTIONAL FORCED AIR
BLOWER KIT (Page 26).
Step 7. CONNECTING GAS LINE (Page 26):
Make connection to gas supply.
Step 8. VERIFYING APPLIANCE OPERATION
(Page 27).
Step 9. INSTALL LOGS, VOLCANIC STONE,
AND GLOWING EMBERS (Page 28).
Step 10. INSTALLING GLASS DOOR
ASSEMBLY (Page 32).
Step 11. BURNER ADJUSTMENTS (Page 32):
Adjust burner to ensure proper flame
appearance.
Step 12. HOOD INSTALLATION (Page 34).
Step 13. ATTACHING SAFETY-IN-
OPERATION WARNINGS (Page 35).
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

DETAILED INSTALLATION STEPS

Step 1. FRAMING

Frame the appliance as illustrated in Figures
13 and 14 on Pages 10 and 11 (Figure 13
applies to corner framing installations only).
All framing details must allow for a minimum
clearance to combustible framing members
as shown in Table 5 on Page 8.
If the appliance is to be elevated above floor
level, a solid continuous platform must be
constructed below the appliance.
Headers may be in direct contact with the
appliance top standoff spacers when they
are bent up vertically, maintaining the 3 in.
clearance to the fireplace top, but must not
be supported by them or notched to fit
around them. All construction above the
appliance must be self-supporting. DO NOT
use the appliance for structural support.
Secure the fireplace to the side framing
members using the unit's nailing flanges
— one top and bottom on each side of the
fireplace front. See Figure 11. Use 8d nails
or their equivalent.
IMPORTANT!
Bend up the appropriate header spacing top
standoffs before installing the fireplace.
Header Spacing Top Standoffs
(two pairs on front edge of firebox top)
Lift up outer pair for
1/2 in. finish materials Lift up inner pair for
5/8 in. finish materials
Unit Nailing Flange
(No clearance to
combustible framing
is required)
Side
Framing
NOTE: The nailing flanges, combustible
members, and screw heads in areas directly
adjacent to the nailing flanges are EXEMPT
from the 1/2 in. clearance to combustible
requirements for the firebox outer wrapper.
Combustible framing may be in direct contact
with the nailing flanges and may be located
closer than 1/2 in. from screw heads and the
firebox wrapper in areas adjacent to the
nailing flanges.
Frame the opening to the exact dimensions
specified in the framing details in this manual.
Figure 11: Unit Secured to Framing by
Nailing Flange