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F- Proper Gas Flow (Approximate)
Gas Flow (Approximate)
TABLE 18
GAS METER CLOCKING CHART
ML193
Unit
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
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
18. If manifold pressure matches table 19 and rate is incor
rect, check gas orifices for proper size and restriction. Re
move temporary gas meter if installed.
TABLE 19
Manifold and Supply Pressure (Outlet) inches w.c.
At All Altitudes For -1 Through -6 Units
Fuel
Model
Input Sizes
Manifold
Pressure in.wg.
Supply
Pressure in.wg.
Min.
Max.
Nat. Gas
All sizes
3.5
4.5
13.0
L.P. Gas
All sizes
10.0
11.0
13.0
G- Proper Combustion
Furnace should operate at least 15 minutes with correct
manifold pressure and gas flow rate before checking com
bustions. Take sample beyond the flue outlet and compare
to table 20.
TABLE 20
ML193
Unit
CO
2
%
For Nat
CO
2
%
For L.P.
-045
7.2 - 7.9
8.6 - 9.3
-070
-090
-110
The carbon monoxide reading should not exceed 50 ppm.
H- High Altitude
NOTE
- In Canada, certification for installations at eleva
tions over 4500 feet (1372 m) is the jurisdiction of local au
thorities.
ML193DF-1 through -6 units require no manifold pressure
adjustments for operation at altitudes up to 10,000 feet
(3048 m) above sea level. However, -7 units and later in
stalled at altitude of 4501 - 10,000 feet (1373 to 3048m) re
quire a pressure switch change which can be ordered sep
arately and manifold de-rate. See table 19 or table 21 for
manifold pressures at varying altitudes. Table 22 lists con
version kit and pressure switch requirements at varying al
titudes.
The combustion air pressure switch is factory-set and re
quires no adjustment.
TABLE 21
Manifold and Supply Line Pressure 0-10,000ft. For -7 Units and Later
ML193
Unit
Gas
Manifold Pressure in. wg.
Supply Line
Pressure
in. w.g.
0 - 10000 ft.
0-4500 ft.
4501-5500 ft.
5501-6500 ft.
6501 -
7500ft.
7501 - 10000ft.
All Sizes
Natural
3.5
3.3
3.2
3.1
3.5
4.5
13.0
LP/propane
10.0
9.4
9.1
8.9
10.0
11.0
13.0
NOTE -
A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion
procedure.
TABLE 22
Conversion Kit and Pressure Switch Requirements at Varying Altitudes
ML193
Unit
Natural to
LP/Propane
High Altitude
Natural Burner Ori
fice Kit
LP/Propane to
Natural
High Altitude Pressure Switch
0 - 7500 ft
(0 - 2286m)
7501 - 10,000 ft
(2286 - 3038m)
0 - 7500 ft
(0 - 2286m)
4501 - 7500 ft
(1373 - 2286m)
7501 -10,000 ft
(2286 - 3048m)
-045
*69W73
73W37
*73W81
93W87
93W88
-070
-090
-110
* Conversion requires installation of a gas valve manifold spring which is provided with the gas conversion kit.
Pressure switch is factory set. No adjustment necessary. All models use the factory-installed pressure switch from 0-4500 feet (0-1370 m).
