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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
16. If manifold pressure matches Table 18 and rate is
incorrect, check gas orifices 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 58. 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
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 18.
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.
Model
Gas
Natural
All Models
Lp/
Propane
Page 46 of 52
0 - 4500 ft.
4501 - 5500 ft.
Low
High
Low
Fire
Fire
Fire
1.7
3.5
1.6
4.5
10.0
4.2
Table 18. Manifold and Supply Line Pressure 0 - 10,000 ft.
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 table below. The maximum
carbon monoxide reading should not exceed 100 ppm.
Model
045
070
090
110
The maximum carbon monoxide reading should not exceed
100 ppm.
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 without manifold adjustment. Units installed
at altitude of 4501 - 10,000 feet (1371 to 3048 m) may
require a pressure switch change which can be ordered
separately. Table 19 lists conversion kit and pressure
switch requirements at varying altitudes.
The combustion air pressure switch is factory-set and
requires no adjustment.
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.
Manifold Pressure in w.g.
5501 - 6500ft.
High
Low
High
Fire
Fire
Fire
3.3
1.5
3.2
9.4
4.0
9.1
Issue 2327
CO
% For Nat
2
Low Fire
High Fire
5.6 - 6.6
7.8 - 8.8
5.6 - 6.5
7.3 - 8.3
5.9 - 6.9
7.8 - 8.8
6.63 - 7.3
8.2 - 9.2
Table 17.
Canada,
certification
6501 - 7500ft.
7501-10000ft.
Low
High
Low
Fire
Fire
Fire
1.5
3.1
1.7
3.9
8.9
4.5
CO
% For LP
2
Low Fire
High Fire
6.6 - 7.6
9.1 - 10.1
6.5 - 7.5
8.6 - 9.6
6.9 - 7.9
9.1 - 10.1
7.3 - 8.3
9.5 - 10.5
for
installations
at
Supply Line
Pressure in
w.g.
0 - 10000 ft.
High
Min.
Max.
Fire
3.5
4.5
13.0
10.0
11.0
13.0
508391-01
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