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 The Glass Enclosure Panel
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.
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" materials and
the inner pair for 5/8" materials.
Bend out the appropriate nailing flanges for
the drywall/finish material to be used. Nailing
flanges are provided for flush framing, 1/2" and
5/8" 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 VOLCANIC STONE, GLOWING
EMBERS, ANd LOGS (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
12 and 13 on Pages 11 and 12 (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" 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" finish materials Lift up inner pair for
5/8" 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"
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" 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
9