Lennox G21Q Series Installation Instructions Manual page 9

NOTE - - If unit is equipped with a Q4 or Q4/5 blower and
side return air is used, it is recommended that the ex-
haust piping drip leg be routed out of the side opposite
the return air duct. This should be done to avoid inter-
ference between the drip leg and the return air duct.
The drip leg may be installed on the return air side pro-
vided it clears the duct.
1 - - Cut PVC pipe (provided) to the desired length for
exit from the unit.
2 - - Slide PVC pipe through rubber grommet in cabi-
net. Care must be taken to center pipe in hole.
3 - - Compression elbow is mounted for left side ex-
haust pipe exit on G21- -40/60/80 units and right
side exit on G21- -100 units. If piping must exit on
other side, disconnect exhaust pressure tubing,
rotate and tighten compression elbow and recon-
nect tubing.
NOTE - - Differential pressure switch will not oper-
ate properly if tubing is kinked.
4 - - Cement PVC pipe to compression elbow which is
already in place.
NOTE - - Care must be taken to assure a secure, tight
seal between compression elbow assembly and
manifold outlet.
5 - - Cement drip leg assembly tee to PVC pipe as
shown in figure 5.
DRIP LEG ASSEMBLY
EXHAUST PIPING
(Field- -provided)
STAND PIPE
(Must be left open.)
CONDENSATE
CONNECTION
(Rotate to proper
drain position before
cementing.)
THREADED PIPE PLUG
(Apply teflon tape to
threads before screwing
plug into adapter.)
FIGURE 5
6 - - Apply teflon tape to threads of pipe plug. Screw
pipe plug into female adapter of drip leg subas-
sembly. Cement drip leg subassembly to drip leg
assembly tee after rotating condensate connec-
tion to suitable drain position.
IMPORTANT - - Leave enough clearance below drip leg
to remove threaded pipe plug for future maintenance.
Debris may buildup in bottom of drip leg and prevent
proper drainage.
IMPORTANT - - Stand pipe must remain open at the top
to vent drain. Open end of pipe must not be used to
connect drain hoses or other condensate hoses.
DRIP LEG
ASSEMBLY TEE
COMPRESSION
ELBOW
(Factory Installed)
PVC PIPE
(Cut to correct
length for exit
from unit.)
FEMALE ADAPTER
3DJH
7 - - Cement exhaust pipe into top of drip leg assembly
tee and route to outside of structure using exhaust
and intake piping requirements listed in section A.
All horizontal runs of exhaust pipe must slope back
toward unit. A minimum of 1/4” (6mm) drop for
each 12” (305mm) of horizontal run is mandatory
for drainage. Horizontal runs of exhaust piping
must be supported every 5 ft. (1524mm) using iso-
lation hangers.
NOTE - - Exhaust piping must be insulated with 1/2”
(13mm) Armaflex or equivalent when run through un-
heated space. Do not leave any area of exhaust pipe
open to outside air; exterior exhaust must be insulated
with 1/2” (13mm) Armaflex or equivalent.
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8 - - Connect condensate drain line (1/2” [13mm] SDR
11 plastic pipe or tubing) to condensate connec-
tion on drip leg assembly and route to open drain.
Condensate line must be sloped downward away
from drip leg to drain. If drain level is above drip
leg, condensate pump must be used to conden-
sate line. 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 con-
densate drip leg and line. Heating cable kit is avail-
able from Lennox in various lengths; 6ft. (1.8m) - -
kit no. 18K48; 24ft. (7.3m) - - kit no. 18K49; and 50ft.
(15.2m) - - kit no. 18K50.
CAUTION
Do not use copper tubing or existing copper con-
densate lines for drain line.
9 - - Seal unused exhaust line piping hole in cabinet
with snap- -plug provided.
CAUTION
The exhaust vent pipe operates under positive
pressure and must be completely sealed to pre-
vent leakage of combustion products into the liv-
ing space.
C - - Intake Piping
1 - - Cement intake piping in slip connector located at
top of unit.
2 - - Determine intake piping size using table 4.
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