Lennox ML196UHE Installation Instructions Manual page 32

Refer to figures 46 and 48 for condensate trap locations.
Figure 54 shows trap assembly using 1/2" PVC or 3/4"
PVC.
NOTE - If necessary the condensate trap may be installed
up to 5' away from the furnace. Use PVC pipe to connect
trap to furnace condensate outlet. Piping from furnace
must slope down a minimum of 1/4" per ft. toward trap.
1 - Determine which side condensate piping will exit
the unit, location of trap, field-provided fittings and
length of PVC pipe required to reach available drain.
2 - Use a large flat head screw driver or a 1/2" drive
socket extension and remove plug (figure 46) from
the cold end header box at the appropriate location
on the side of the unit. Install provided 3/4 NPT street
elbow fitting into cold end header box. Use Teflon
tape or appropriate pipe dope.
NOTE - Cold end header box drain plugs are facto-
ry installed. Check the unused plug for tightness to
prevent leakage.
3 - Install the cap over the clean out opening at the base
of the trap. Secure with clamp. See Figure 54.
CONDENSATE TRAP AND PLUG LOCATIONS
(Unit shown in upflow position)
Trap
(same on
right side)
1-1/2 in.
NOTE - In upflow applications where side return
sate trap, filter rack must be installed beyond
condensate trap or trap must be re-located to
avoid interference.
Figure 46
4 - Install drain trap using appropriate PVC fittings,
glue all joints. Glue the provided drain trap as
shown in Figure 54. Route the condensate line to
an open drain. Condensate line must maintain a 1/4"
downward slope from the furnace to the drain.
Plug
(same on left side)
Page 32
5 - Figure 49 and Figure 51 shows the furnace and
evaporator coil using a separate drain. If necessary
the condensate line from the furnace and evaporator
coil can drain together. See Figure 50, Figure 52,
and Figure 53. Upflow furnace (Figure 52) - In
upflow furnace applications the field provided vent
must be a minimum 1" to a maximum 2" length
above the condensate drain outlet connection.
Any length above 2" may result in a flooded heat
exchanger if the combined primary drain line were to
become restricted. Horizontal furnace (Figure 53)
- In horizontal furnace applications the field provided
vent must be a minimum 4" to a maximum 5" length
above the condensate drain outlet connection.
Any length above 5" may result in a flooded heat
exchanger if the combined primary drain line were to
become restricted.
NOTE - In horizontal applications it is recommended
to install a secondary drain pan underneath the unit
and trap assembly.
NOTE - Appropriately sized tubing and barbed fit-
ting may be used for condensate drain. Attach to the
drain on the trap using a hose clamp. See Figure 47.
CAUTION
Do not use copper tubing or existing copper condensate
lines for drain line.
Field Provided Drain Components
Elbow
Tubing
Figure 47
6 - If unit will be started immediately upon completion of
installation, prime trap per procedure outlined in Unit
Start-Up section.
Condensate line must slope downward away from the
trap to drain. If drain level is above condensate trap,
condensate pump must be used. Condensate drain
line should be routed within the conditioned space to
avoid freezing of condensate and blockage of drain
line. If this is not possible, a heat cable kit may be used
on the condensate trap and line. Heating cable kit is
available from Lennox in various lengths; 6 ft. (1.8m) -
kit no. 26K68 and 24 ft. (7.3m) - kit no. 26K69.
Barbed Fitting
Hose Clamp