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Gas Pressure Adjustment
Gas Flow (Approximate)
Seconds for One Revolution
Natural
Capacity
1 cu ft
Dial
-045
80
-070
55
-090
41
-110
33
Natural - 1000 btu/cu ft
Table 11. Gas Meter Clocking Chart
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
11. If manifold pressure matches Table 13 and rate is
incorrect, check gas orifices for proper size and restriction.
Remove temporary gas meter if installed.
Supply Pressure Measurement
A threaded plug on the inlet side of the gas valve provides
access to the supply pressure tap. Remove the threaded
plug, install a field-provided barbed fitting and connect a
manometer to measure supply pressure. Turn OFF unit
remove manometer and replace the threaded plug after
measurements have been taken.
Manifold Pressure Measurement
1. Remove the threaded plug from the outlet side of
the gas valve and install a field provided barbed
fitting. Connect to a manometer to measure manifold
pressure.
2.
Start unit and allow 5 minutes for unit to reach steady
state.
Capacity
Gas
Natural
All Sizes
LP / Propane
NOTE: A natural to LP propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation
instruction for the conversion procedure.
507271-02
LP
2 cu ft
1 cu ft
2 cu ft
Dial
Dial
160
200
110
136
82
102
66
82
LP - 2500 btu/cu ft
Manifold and Supply Line Pressure 0 - 10,000 ft.
Manifold Pressure in. w.g.
4,501 - 5,500
0 - 4,500 ft.
ft.
3.5
3.3
10.
9.4
3.
While waiting for the unit to stabilize, observe the
flame. 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 13.
Dial
NOTE: Shut unit off and remove manometer as soon as an
400
accurate reading has been obtained. Take care to remove
272
barbed fitting and replace threaded plug.
204
164
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 and compare to the tables below. The maximum
carbon monoxide reading should not exceed 100 ppm.
Capacity
All
High Altitude Information
NOTE: In
elevations over 4500 feet (1371 m) is the jurisdiction of
local authorities.
Units may be installed at altitudes up to 10,000 ft. above
sea level. See Table 13 for derate manifold values. Units
installed at altitude of 7501 - 10,000 feet require an orifice
change. Units installed at altitudes of 4501 - 10,000 feet
(1371 to 3048 m) require a pressure switch change which
can be ordered separately. Table 14 lists conversion kit
and pressure switch requirements at varying altitudes.
The combustion air pressure switch is factory-set and
requires no adjustment.
5,501 - 6,500
6,501 - 7,500
ft.
ft.
3.2
3.1
9.1
8.9
Table 13.
Issue 1917
CO2% for Nat
7.2 - 7.9
Table 12.
Canada,
certification
Supply Line Pressure
7,501 -
10,000 ft.
3.5
10.0
CO2% for L.P.
8.6 - 9.3
for
installations
at
in. w.g.
0 - 10,000 ft.
4.5
13.0
11.0
13.0
Page 41 of 51
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