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Model
Input Size
045
LP/Propane
070
LP/Propane
090
LP/Propane
110
LP/Propane
Model Input
High Altitude Pressure Switch Kit
Size
045
0-4500 ft
070
110
090
No Change
090 (X)
110
NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit instal-
lation instruction for the conversion procedure.
Other Unit Adjustments
NOTE - Do not secure the electrical conduit directly to the
air ducts or structure.
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are lo-
cated in the blower compartment, attached to the back
side of the blower. These auto reset limits are factory-set
and require no adjustment.
Flame Rollout Switch
The manually reset switch is located on the front of the
burner box.
Pressure Switch
The pressure switch is located in the heating compartment
adjacent to the combustion air inducer. The switch checks
for proper combustion air inducer operation before allow-
ing ignition trial. The switch is factory-set and requires no
adjustment.
Manifold Pressure Settings at all Altitudes
Gas
0 - 4500 ft.
Nat
3.5
10.0
Nat
3.5
10.0
Nat
3.5
10.0
Nat
3.5
10.0
Pressure Switch and Gas Conversion Kits at all Altitudes
4501-7500 ft
7501-10,000 ft
No Change
80W52
No Change
80W51
80W52
TABLE 11
4501 - 7500 ft .
7501 - 10,000 ft.
3.5
3.5
10.0
10.0
3.3
3.5
10.0
10.0
3.3
3.5
10.0
10.0
3.3
3.5
10.0
10.0
TABLE 12
Natuarl Gas Orifice Kit
0 - 7500 ft
7501 - 10,000 ft
73W81
73W37
Temperature Rise
After the furnace has been started, and supply and return
air temperatures have been allowed to stabilize, check the
temperature rise. If necessary, adjust the blower speed
to maintain the temperature rise within the range shown
on the unit nameplate. Increase the blower speed to de-
crease the temperature. Decrease the blower speed to
increase the temperature rise. Failure to adjust the tem-
perature rise may cause erratic limit operation.
Fan Control
The heat fan-on time of 30 seconds is not adjustable. The
heat fan-off delay (amount of time that the blower oper-
ates after the heat demand has been satisfied) may be
adjusted by changing the jumper position across the five
pins on the integrated control. The unit is shipped with a
factory fan-off delay setting of 120 seconds. The fan-off
delay affects comfort and is adjustable to satisfy individual
applications. Adjust the fan-off delay to achieve a supply
air temperature between 90° and 110°F at the moment
that the blower is de-energized. Longer off delay settings
provide lower return air temperatures; shorter settings
provide higher return air temperatures. See figure 23.
Page 24
Line Pressure in. wg.
Min
Max
4.5
13.0
11.0
13.0
4.5
13.0
11.0
13.0
4.5
13.0
11.0
13.0
4.5
13.0
11.0
13.0
LP/Propane Orifice Kit
0 - 7500 ft
7501 - 10,000 ft
11K49
11K44
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