Lennox SLP99UHV Series Unit Information page 59

Condensate Piping
This unit is designed for either right- or left-side exit of
condensate piping in upflow applications. In horizontal
applications, the condensate trap must extend below the
unit. An 8" service clearance is required for the conden-
sate trap. Refer to FIGURE 39 and FIGURE 41 for con-
densate trap locations. FIGURE 47 shows trap assembly.
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 - For furnaces with a 1/2" drain connection use a 3/8
allen wrench and remove plug (FIGURE 40) from
the cold end header box at the appropriate location
on the side of the unit. Install field-provided 1/2 NPT
male fitting into cold end header box. For furnaces
with a 3/4" drain connection use a large flat head
screw driver or a 1/2" drive socket extension and
remove plug. Install provided 3/4 NPT street elbow
fitting into cold end header box. Use Teflon tape or
appropriate pipe dope
3 - Install the cap over the clean out opening at the
base of the trap. Secure with clamp. See FIGURE
47.
4 - Install drain trap using appropriate PVC fittings,
glue all joints. Glue the provided drain trap as
shown in FIGURE 47. Route the condensate line
to an open drain. Condensate line must maintain a
1/4" downward slope from the furnace to the drain.
5 - FIGURE 43 and FIGURE 44 show 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 42, FIGURE
45 and FIGURE 46. Upflow furnace (FIGURE 45)
- 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 46) - 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.
6 - If unit will be started immediately upon completion
of installation, prime trap per procedure outlined in
Unit Start-Up section.
CONDENSATE TRAP AND PLUG LOCATIONS
(Unit shown in upflow position)
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.
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 fitting
may be used for condensate drain. Attach to the
drain on the trap using a hose clamp. See FIGURE
40.
Field Provided Drain Components
Elbow
Tubing
Condensate line must slope downward away from the trap
to drain. If drain level is above condensate trap, conden-
sate 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 pos-
sible, 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.
Page 59
Plug
(same on left side)
FIGURE 39
Barbed Fitting
Hose Clamp
FIGURE 40