Lennox SL280UHNV - Page 36

Page 36
Operating Signal Pressure Measurement -01 to -04 models
FIGURE 21
TABLE 20
-01 Through -04 Models
Unit
Production Resonance (more air) Di󰀩culty Igniting (less air)
Orice Size (Part No) Orice Size Cat No Orice Size Cat No
-060 0.969 (08) 1.000 19X30 0.937 19X37
-080 1.094 (07) 1.125 19X31 0.995 19X36
-100 1.250 (06) 1.281 19X39 1.219 19X32
TABLE 21
-01 through -04
Unit
Pressure Switch 4501-7500ft
Natural LP/Propane
-060 20K91 No Change
-080
No Change N/A
-100
ALL -05 Models No Change N/A
Proper Combustion -01 through -04 Models
Furnace should operate a minimum 15 minutes with cor-
rect manifold pressure and gas ow rate before checking
combustion. Take combustion sample beyond the ue out-
let and compare to the Table 21. The maximum carbon
monoxide reading should not exceed 100 ppm.
TABLE 22
Firing Rate CO
2
% For Natural CO
2
% For LP
High Fire
6.0 - 7.8 7.5-9.9
Low Fire
High Altitude -01 through -04 Models
Units may be installed at altitudes up to 7,500 ft. above
sea level. See Table 18 and Table 19 for de-rate mani-
fold 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.