Installation Guide
507052-04Page 46 of 53 Issue 1727
Capacity Gas
Manifold Pressure in w.g.
Supply Line
Pressure in
w.g.
0 - 10000 ft.
0 - 4500 ft. 4501 - 5500 ft. 5501 - 6500ft. 6501 - 7500ft. 7501-10000ft.
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Low
Fire
High
Fire
Min. Max.
All Models
Natural 1.7 3.5 1.6 3.3 1.5 3.2 1.5 3.1 1.7 3.5 4.5 13.0
LP/Propane 4.9 10.0 4.6 9.4 4.4 9.1 4.3 8.9 4.9 10.0 11.0 13.0
Table 16. Manifold and Supply Line Pressures Altitudes
11. Set the thermostat to desired setting.
NOTE: When unit is initially started, steps 1 through
11 may need to be repeated to purge air from gas line.
12. If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call your service
technician or gas supplier.
Turning Off Gas to Unit
1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the unit if service is to
be performed.
3. Remove the heating compartment access panel.
4. Move gas valve switch to OFF.
5. Replace the heating compartment access panel.
Gas Pressure Adjustment
Gas Flow (Approximate)
Table 14.
Gas Meter Clocking Chart
Capacity
Seconds for One Revolution
Natural LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
Dial
-045 80 160 200 400
-070 55 110 136 272
-090 41 82 102 204
-110 33 66 82 164
Natural - 1000 btu/cu ft LP - 2500 btu/cu ft
Furnace should operate at least 5 minutes before checking
gas ow. Determine time in seconds for two revolutions of
gas through the meter. (Two revolutions assures a more
accurate time.) Divide by two and compare to time in Table
14. If manifold pressure matches Table 16 and rate is
incorrect, check gas orices for proper size and restriction.
Remove temporary gas meter if installed.
NOTE: To obtain accurate reading, shut off all other gas
appliances connected to meter.
Supply Pressure Measurement
A pressure post on the inlet side of the gas valve provides
access to the supply pressure. Back out the 3/32 Hex screw
one turn, connect a piece of 5/16” tubing and connect a
manometer to measure supply pressure.
NOTE: Shut unit off and remove manometer as soon as
an accurate reading has been obtained. Take care to re-
tighten the 3/32 Hex screw.
Manifold Pressure Measurement
1. A manifold post located on the gas valve provides
access to the manifold pressure. See Figure 60. Back
out the 3/32 Hex screw one turn, connect a piece of
5/16” tubing and connect to a manometer to measure
manifold pressure.
2. Start unit and allow 5 minutes for unit to reach steady
state.
3. While waiting for the unit to stabilize, observe the
ame. Flame should be stable and should not lift from
burner. Natural gas should burn blue.
4. After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in
Table 16.
NOTE: Shut unit off and remove manometer as soon as
an accurate reading has been obtained. Take care to re-
tighten the 3/32 Hex screw.
Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas ow rate before checking
combustion. Take combustion sample beyond the ue
outlet and compare to the tables below. The maximum
carbon monoxide reading should not exceed 100 ppm.
Table 15.
Capacity
CO
2
% for Nat CO
2
% for L.P.
Low Fire High Fire Low Fire High Fire
045 5.6 - 6.6 7.8 - 8.8 6.6 - 7.6 9.1 - 10.1
070 5.5 - 6.5 7.3 - 8.3 6.5 - 7.5 8.6 - 9.6
090 5.9 - 6.9 7.8 - 8.8 6.9 - 7.9 9.1 - 10.1
110 6.3 - 7.3 8.2 - 9.2 7.3 - 8.3 9.5 - 10.5
The maximum carbon monoxide reading should not exceed
100 ppm.