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Operating Signal Pressure Measurement
FIGURE 20
TABLE 20
Unit
Production
Resonance (more air)
Difficulty Igniting (less air)
Orifice Size (Part No)
Orifice Size
Cat No
Orifice Size
Cat No
-060
0.969 (08)
1.000
19X30
0.937
19X37
-080
1.094 (07)
1.125
19X31
0.995
19X36
G- Proper Combustion
Furnace should operate a minimum 15 minutes with cor-
rect manifold pressure and gas flow rate before check
-
ing combustion. Take combustion sample beyond the flue
outlet and compare to TABLE 21.
The maximum carbon
monoxide reading should not exceed 100 ppm.
TABLE 21
Firing Rate
CO
2
% For Natural
CO
2
% For LP
High Fire
6.0 - 7.8
7.5-9.9
Low Fire
H- High Altitude
Units may be installed at altitudes up to 7,500 ft. above
sea level. See TABLE 18 and TABLE 19 for de-rate man
-
ifold values. Units installed at altitude of 4501 - 7,500 feet
require a pressure switch change which can be ordered
separately. TABLE 22 lists pressure switch requirements
at high altitude.
The combustion air pressure switch is factory-set and re-
quires no adjustment.
TABLE 22
Unit
Pressure Switch 4501-7500ft
Natural
LP/Propane
-060
20K91
No Change
-080
No Change
N/A
-100
