Lennox 99W41 Installation Instructions Manual

©2020
INSTALLATION INSTRUCTIONS FOR HEAT EXCHANGER REPLACEMENT KIT
USED ON LG/KG/ZG 036, 048, 060, 072, 074 PACKAGED ROOFTOP UNITS

Shipping and Packing List

Package 1 of 1 contains:
1- Heat exchanger assembly
1- Bag assembly containing:
22-Screws
1-CAB gasket
6-Seals (mastic)
5-Wire ties
1-Foam PVC tape (17" length)
Check packaging for shipping damage. Contact the last
carrier immediately if any shipping damage is found.

Application

See table for usage.
Heat Output
Cat. No. / Ass'y No.
99W41 / 610414-01
99W42 / 610414-02
99W43 / 610414-03
10M86 / 610414-04
13J82 / 610414-05
13J83 / 610414-06
13U10 / 610414-07
16G31 / 610414-08 150K 4 Stg. Stainless Steel
WARNING
Improper installation, adjustment, alteration, ser­
vice or maintenance can cause property damage,
personal injury or loss of life. Installation and ser­
vice must be performed by a licensed professional
HVAC installer or equivalent, service agency, or the
gas supplier
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in­
jury. Take care while handling this equipment and
wear gloves and protective clothing.
PACKAGED UNITS KITS
AND ACCESSORIES
507095-03
12/2020
Supersedes 507095-02
Material
KBtuh
150 Aluminized
105/108 Aluminized
65/70 Aluminized
65/70 Stainless Steel
105/108 Stainless Steel
150 Stainless Steel
108K NOX
Aluminum
ZG only

LG/KG-Before Removing Heat Exchanger

Note - Do not damage roofing surface during
replacement.
1- Disconnect all electrical power to unit and turn off
main gas valve.
2- Disconnect power at the main breaker if the external
disconnect is installed on the gas inlet mullion.
3- Disconnect gas inlet pipe at gas valve.
4- Open or remove heat and compressor access
panels. See figure 1.
REMOVE PANELS - LG/KG
HEAT ACCESS
PANEL
5- Remove the gas inlet mullion. See figure 1. If conduit
is run to the mullion, move the mullion out of the way.
Disconnect wiring and remove conduit if necessary.
6- Disconnect P19 from J19. See figure 2.
7- Disconnect wiring
combustion air blower prove switch, and flame rollout
switch. On LGH/KG/ZG units, disconnect wiring to
the primary limit. See figure 2. On LGM150 units,
remove the primary limit.
Note - Wires are marked for identification during
reassembly.
8- Remove the two screws securing the combustion air
blower prove switch. Discard the switch if tabs are
broken. Retain the switch for reassembly if tabs are
intact. See figure 2.
9- Disconnect the air tubing to the fitting on the
vestibule. See figure 3.
Page 1
HEAT EXCHANGER
REPLACEMENT KIT
GAS INLET
COMPRESSOR
MULLION
ACCESS PANEL
FIGURE 1
to ignitor, flame sensor,