507371-02
Issue 1706
Page 5 of 5
C - Gas Flow (Approximate)
NOTE:
To obtain accurate reading, shut off all other gas
appliances connected to meter.
Furnace should operate at least 5 minutes before checking
gas flow. 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 2. If manifold pressure matches Table 1 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Unit Capacity
Seconds for One Revolution
LP
1 cu ft Dial
2 cu ft Dial
-045
200
400
-070
136
272
-090
102
204
-110
82
164
-135
68
136
2500 btu/cu ft
Table 2. Gas Meter Clocking Chart
D- Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking
combustion. Take combustion sample beyond the flue
outlet. See Table 3 through Table 5 .
NOTE:
Shut unit off and remove manometer as soon as
supply line pressure, manifold pressure and combustion
sample have been obtained. Take care to replace pressure
tap plug.
Unit Capacity
CO
2
% for LP
Low Fire
High Fire
-045
6.4 - 7.4
8.8 - 9.8
-070
6.3 - 7.3
8.7 - 9.8
-090
6.8 - 7.8
8.9 - 9.9
-110
7.1 - 8.1
9.3 - 10.3
-135
7.1 - 8.2
9.1 - 10.1
The carbon monoxide reading should not exceed 100 ppm.
Table 3.
A952 & 95G2 Upflow / Horizontal Furnaces
Unit Capacity
CO
2
% for LP
Low Fire
High Fire
-045
6.6 - 7.6
9.1 - 10.1
-070
6.5 - 7.5
8.6 - 9.6
-090
6.9 - 7.9
9.1 - 10.1
-110
7.3 - 8.3
9.5 - 10.5
The carbon monoxide reading should not exceed 100 ppm.
Table 4.
A952 & 95G2 Downflow Furnaces
All Models
Firing Rate CO
2
% for Nat CO
2
% for LP
Upflow/
Horizontal
High Fire
6.8 - 7.4
7.5 - 9.0
Low Fire
4.2 - 5.7
5.0 - 6.0
Downflow
High Fire
6.0 - 7.4
6.9 - 8.4
Low Fire
4.8 - 6.0
5.7 - 7.0
The carbon monoxide reading should not exceed 100 ppm.
Table 5. A802 & 80G2
E - Turning Off Gas to the Unit
1. Set the thermostat to its lowest setting.
2. Turn off all the electrical power to the unit.
3.
Remove the unit access panel.
4. Move the switch on the gas valve to OFF. Do not force
the switch.
