Lennox G26 series Installation Instructions Manual page 8

Pipe used for exhaust and intake lines should be sized ac-
cording to table 4. Note that maximum length of vent pipe is
for one run; either intake or exhaust. Maximum vent length
given is not the total length of intake + exhaust vents.
Each 90 ° elbow is equivalent to 5 feet (1.52m) of vent pipe.
Two 45 ° elbows are equivalent to one 90 ° elbow. One
45°elbow is equal to 2.5 feet (.76m) of vent pipe.
If intake and exhaust piping runs are not equal in length and
number of elbows, the larger diameter pipe must be used
for both runs.
TABLE 4
VENT PIPE SIZING TABLE FOR G26 FURNACES
MINIMUM DIAMETER OF INTAKE/EXHAUST PIPE
Vent Pipe G26-50 G26-75 G26-100 G26-125
Equivalent Length 50,000 75,000 100,000 125,000
Max, Feet (Meters) BTU BTU BTU BTU
15 (4.57m) 1-1/2" 2" 2" 2"
20 (6.10m) 2" 2" 2" 3"
25 (7.62m) 2" 2" 2" 3"
30 (9.14m) 2" 2" 3" 3"
40 (12.19m) 2" 2" 3" 3"
50 (15.24m) 2" 2" 3" 3"
55 (16,76m) 2" 2" 3" 3"
60 (10.29m) 3" 3" 3" 3"
70 (21.34m) 3" 3" 3" 3"
80 (24.38m) 3" 3" 3° 3"
90 (27.43m) 3" 3" 3" 3"
100 (30.48m) 3" 3" 3" 3"
110 (33.53m) 3" 3" 3" 3"
120 (36.58m) 3" 3" 3" 3"
130 (39.62m) 3" 3" 3" -
NOTE - M inchpipe forG26-50is 5 feet and2 elbowsof 1.5 inch diameter
pipe.
NOTE - M inchpipe for G26-75 is 5 feetand 2 elbowsof 2 inchdiameter
pipe.
NOTE - M inchpipe forG26-100 is 5 feetand2 elbows of 2 inchdiameter
pipe.
NOTE - M inchpipe for G26-125 is 5 feetand2 elbowsof 2 inchdiameter
pipe.
NOTE - When a WTtO( termination kit is installed as part of
the intake and exhaust piping, the two 2 inch diameter 90 °
elbows and the 27 inch pipe (in the kit) should be included
in the maximum vent pipe length for each run.
For -50 and -75 kBtuh units, connections are provided for 2
inch diameter venting which should satisfy most venting re-
quirements. No transition pieces are provided or needed
for 2 inch venting.
For -100 and -125 kBtuh units, the intake connection is
sized for 3 inch diameter pipe. The exhaust connection has
a 2 inch nipple. A pipe transition piece is shipped with the
unit to connect to 3 inch pipe. See figure 7 for 2 inch and 3
inch venting applications.
Most venting applications will require 3 inch venting for
proper unit operation. For no reason should the intake
and exhaust pipe be different diameter pipes. Regard-
less of the diameter of pipe used, the standard roof and wall i
terminations described in section Intake and Exhaust Pip-
ing Terminations should be used. Exhaust piping must ter-
minate with 1-1/2 inch pipe for 1-1/2 inch or 2 inch venting
and 2 inch pipe for 3 inch venting.
G26-100 OR -125 WITH 2 IN. VENTING
2 IN. VEN'_,,._P_ ¢,..1 3 IN. X 2 IN.
I-1" /REDU'%E'D
I I _ PROVIDED
2IN I 3IN'
OUT IN
G26-100 OR -125 WITH 3 IN. VENTING
31N. X21N.
REDUCER _ IN. VENT PIPE
2,N IV
PROVIDED _
I I
NIPPLE
2IN. I 3IN.
OUT IN
FIGURE 7
All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.
1 - Measure and cut vent pipe to desired length.
2 - Debur and chamfer end of pipe, removing any ridges
or rough edges. If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint.
3 - Clean and dry surfaces to be joined.
4 - Test fitjoint and mark depth of fitting on outside of pipe.
5 - Uniformly apply liberal coat of PVC primer for PVC or
ABS cleaner for ABS to inside socket surface of fitting
and male and of pipe to depth of fitting socket.
6 - Promptly apply solvent cement to end of pipe and in-
side socket surface of fitting. Cement should be ap-
plied lightly but uniformly to inside of socket. Take care
to keep excess cement out of socket. Apply second
coat to end of pipe.
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