Horizontal Venting; High Altitude - Lennox F8AUH series Service Manual

Furnace
Model No Model No.
F8AUH**−24−045
F8AUH**−24−060
F8AUH**−36−060
F8AUH**−24−075
F8AUH**−36−075
F8AUH**−48−075
F8AUH**−48−100
F8AUH**−60−100
F8AUH**−48−120
F8AUH**−60−120
VENTING NOTES − Elbows −
Tees −
Transition − 3 inch to 4 inch (76 mm to 102 mm) transition is equivalent to 2 feet (0.61 m) of straight vent pipe.

Transition furnished with power venter should be installed on top of flue adaptor at induced draft blower.
NOTE − All horizontal venting applications require optional Sidewall Power Venting Kit.
Refer to table below for manifold pressure settings for
Installations at different altitudes and different fuels.
NOTE−In Canada, certification for installations over
4500 ft. (1372m) above sea level is the jurisdictionof
the local authorities.
Manifold Absolute Pressure in. w.c. (kPa)
ALTITUDE ft. (m)
0−4500 4500−5500
FUEL
(0−1372) (1372−1676)
NAT 3.5 (0.87) 3.4 (0.85)
LP 9.5 (2.36) 9.2 (2.29)
HORIZONTAL VENTING REQUIREMENTS
(Requires Optional Side Wall Power Venting Kit)
Vent Pipe Diameter
Furnace Connection
in. mm
3 76
4 102
One 3 inch (76 mm) diameter 45_ elbow is equivalent to 3 feet (1.0 m) of straight vent pipe.
One 4 inch (102 mm) diameter 45_ elbow is equivalent to 4 feet (1.2 m) of straight vent pipe.
One 3 inch (76 mm) 90_ elbow is equivalent to 5 feet (1.5 m) of straight vent pipe.
One 4 inch (102 mm) 90_ elbow is equivalent to 7 feet (2.1 m) of straight vent pipe.
Two 45_ elbows are equal to one 90_ elbow.
One 3 inch (76 mm) diameter tee is equivalent to 19 feet (5.8 m).of straight vent pipe.
One 4 inch (102 mm) diameter tee is equivalent to 25 feet (7.6 m).of straight vent pipe.
HIGH ALTITUDE DERATE
5500−6500 6500−7500
(1676−1981) (1982−2286)
3.3 (0.82) 3.2 (0.80)
8.9 (2.21) 8.6 (2.14)
Vent Pipe Minimum
Equivalent Length
feet meters
10 3.0
10 3.0
The combustion air blower pressure switches are factory
set and are not to be adjusted.
At elevations of 4500 ft. (1372m) or greater, change factory
installed pressure switch to switch listed in table below.
UNIT MODEL
F8AUH**−24−045(X)
F8AUH**−24−060
F8AUH**−36−060(X)
F8AUH**−24−075
F8AUH**−36−075(X)
F8AUH**−48−75(X)
F8AUH**−48−100(X)
F8AUH**−60−100(X)
F8AUH**−48−120
F8AUH**−60−120(X)
Page 6
Vent pipe Maximum
Equivalent Length Transition Required
feet meters

3 to 4
60 18.0
60 18.0
PRESSURE SWITCH

Horizontal Venting

in. mm

76 to 102
− − − − − − − −
PART NUMBER
NO CHANGE
NO CHANGE
88J80
18L24
18L24