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To convert the AFII burner from confined space to outside
combustion air, remove the three screws which attach the
inlet air scoop to the burner and insert 4" (102 mm) direct air
intake piping.
The use of a barometric relief placed in the intake pipe is
recommended when outdoor combustion air is directly
connected to the burner. This will allow confined space air
to be used as combustion air in the event that the opening
to the outdoor air becomes blocked. Use a barometric relief
in the intake to reduce the chance of sooting.
CAUTION
DO NOT USE a barometric draft relief in exhaust vent
pipe if outdoor combustion air is connected directly
to the burner.
Removal of Unit from Common Venting System
In the event that an existing furnace is removed from a
venting system commonly run with separate appliances,
the venting system is likely to be too large to properly vent
the remaining attached appliances. The following test
should be conducted while each appliance is in operation
and the other appliances not in operation remain con-
nected to the common venting system. If venting system
has been installed improperly, the system must be cor-
rected as outlined in the previous section.
1 − Seal any unused openings in the common venting
system.
2 − Visually inspect venting system for proper size and
horizontal pitch and determine there is no blockage or
restriction, leakage, corrosion or other deficiencies
which could cause an unsafe condition.
3 − Insofar as is practical, close all building doors and win-
dows and all doors between the space in which the ap-
pliances remaining connected to the common venting
system are located and other spaces of the building.
Turn on clothes dryers and any appliances not con-
nected to the common venting system. Turn on any
exhaust fans, such as range hoods and bathroom ex-
hausts, so they will operate at maximum speed. Do not
operate a summer exhaust fan. Close fireplace damp-
ers.
4 − Following the lighting instruction on the unit, place the
appliance being inspected in operation. Adjust ther-
mostat so appliance will operate continuously.
5 − Test for spillage using a draft gauge.
6 − After it has been determined that each appliance re-
maining connected to the common venting system
properly vents when tested as outlined above, return
doors, windows, exhaust fans, fireplace dampers and
any other fuel burning appliance to its previous condi-
tion of use.
7− If improper venting is observed during any of the
above tests, the common venting system must be cor-
rected.
Horizontal Venting
The OF23 is approved for horizontal venting with the fol-
lowing mechanical vent systems:
Tjernlund (sideshot) #SS1C (Cat. #35E08) or Field Con-
trols #SWG−5 (Cat. #35P08) with the CK−61 (Cat. #18N28)
control kit. Refer to the manufacturers’ installation instruc-
tions for proper installation procedures and service parts
information.
The barometric draft control must be installed within 18
inches of the furnace flue outlet. See figure 12 for baromet-
ric draft control location.
Do not common vent with any other appliance when using
sidewall vent system.
The maximum equivalent length of pipe is 70 equivalent
feet. A 90
_
elbow equals 6 ft. Minimum length is 15 equiva-
lent feet. Calculate the equivalent vent pipe footage from
the furnace to the mechanical vent system (Tjernlund or
Field Controls) by adding the straight vent pipe length and
the equivalent elbow lengths together.
Front Flue / Horizontal Venting
Rear Flue / Horizontal Venting
barometric
control*
control for
horizontal
venting
Figure 12
*Barometric control must be installed in the horizontal venting
system and located within 18" of flue outlet of furnace.
horizontal
venting
control
barometric
control*
