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adapter kit (available as Lennox part 10L34) to assist in
measurement.
1 − Connect test gauge +" connection to manifold pres
sure tap on the gas valve.
2 − Tee into the gas valve regulator vent hose and con-
nect test gauge −" connection.
3 − Start unit on low heat (35% rate) and allow 5 minutes
for unit to reach steady state.
4 − While waiting for the unit to stabilize, notice the
flame. Flame should be stable and should not lift from
burner. Natural gas should burn blue.
5 − After allowing unit to run for 5 minutes, record man-
ifold pressure and compare to value given in table 29.
6 − Repeat steps 3, 4 and 5 on high fire.
CAUTION
Do not attempt to make adjustments to the gas valve.
F− Proper Gas Flow (Approximate)
TABLE 26
GAS METER CLOCKING CHART
SLP98
Unit
Seconds for One Revolution
Natural
LP
1 cu ft
Dial
2 cu ft
Dial
1 cu ft
Dial
2 cu ft
DIAL
−70
55
110
136
272
−90
41
82
102
204
−110
33
66
82
164
−135
27
54
68
136
Natural−1000 btu/cu ft LP−2500 btu/cu ft
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 26 below. If manifold pressure matches table 29 and
rate is incorrect, check gas orifices for proper size and re-
striction.
NOTE
− To obtain accurate reading, shut off all other gas ap-
pliances connected to meter.
G− Proper Combustion
Furnace should operate minimum 15 minutes with correct
manifold pressure and gas flow rate before checking com-
bustion. Take combustion sample beyond the flue outlet
and compare to the tables below.
The maximum 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.
SLP98UHV units require no manifold pressure adjustments
for operation at altitudes up to 10,000 feet (3048m) above
sea level. Units installed at altitude of 7,501 to 10,000 feet
(2287 to 3048m) require a pressure switch change per table
29. Table 29 lists conversion kit requirements, pressure
switch requirements and manifold pressures at all altitudes.
NOTE − The values given in table are measurements only.
The gas valve should not be adjusted.
The combustion air pressure switch is factory−set and re-
quires no adjustment.
NOTE − A natural to L.P. propane gas changeover kit is nec-
essary to convert this unit. Refer to the changeover kit
installation instruction for the conversion procedure.
TABLE 27
High Fire
SLP98UHV Unit
CO
2
%
For Nat
CO
2
%
For L.P.
36B−070
7.5 − 8.5
9.0 − 10.0
36C−090
60C−090
60C−110
60D−135
The maximum carbon monoxide reading should not exceed 50 ppm.
TABLE 28
Low Fire
SLP98UHV Unit
CO
2
%
For Nat
CO
2
%
For L.P.
36B−070
5.2 − 6.2
6.7 − 7.7
36C−090
60C−090
60C−110
60D−135
The maximum carbon monoxide reading should not exceed 50 ppm.