Lennox SL280UHNX Series Installation and operation manual

Page 1
UNIT INFORMATIONUNIT INFORMATION
Service Literature
©2016 Lennox Industries, Inc.
WARNING
Improper installation, adjustment, alteration,
service or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional HVAC
installer (or equivalent), service agency or the gas
supplier.
WARNING
To prevent serious injury or death:
1- Lock-out/tag-out before performing maintenance.
2- If system power is required (e.g., smoke detector
maintenance), disable power to blower, remove
fan belt where applicable, and ensure all
controllers and thermostats are set to the “OFF”
position before performing maintenance.
3- Always keep hands, hair, clothing, jewelry, tools,
etc., away from moving parts.
SL280UHV(X) series units are 80% e󰀩ciency gas furnac-
es used for upow or horizontal applications only, man-
ufactured with Lennox Duralok heat exchangers formed
of aluminized steel. SL280UHV(X) units are available in
heating capacities of 66,000 to 132,000 Btuh and cooling
applications up to 5 tons. Refer to Engineering Handbook
for proper sizing.
Units are factory equipped for use with natural gas. Kits
are available for conversion to LPG operation. SL280UH-
V(X) model units are equipped with a communicating
SureLight® two-stage variable speed integrated control.
SL280UHV(X) unit meets the California Nitrogen Oxides
(NOx) Standards and California Seasonal E󰀩ciency re-
quirements. All units use a redundant gas valve to assure
safety shut-o󰀨 as required by C.S.A.
All specications in this manual are subject to change.
Procedures outlined in this manual are presented as a
recommendation only and do not supersede or replace lo-
cal or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual (ex-
cept where noted) are recommendations only and do not
constitute code.
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal
injury. Take care while handling this equipment and
wear gloves and protective clothing.
TABLE OF CONTENTS
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 3
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . Page 17
II Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 47
III Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 47
IV Heating System Service Checks . . . . . . . . . Page 48
V Typical Operating Characteristics . . . . . . . . . Page 51
VI Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 52
VII Wiring and Sequence of Operation . . . . . . Page 54
VIII Field Wiring and Jumper Settings . . . . . . . Page 59
IX Program Unit Capacity Size Mode . . . . . . . Page 73
X Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . Page 74
SL280UHV
Corp 1116-L4
Revised 05/2022
LENNOX®COMMUNICATING SL280UHNV SERIES UNITS

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. SL280UH070V36A SL280UH090V36B SL280UH090V48B
Model No. - Low Nox SL280UH070XV36A - - - SL280UH090XV48B
1 AFUE 80% 80% 80%
High
Fire
Input - Btuh 66,000 88,000 88,000
Output - Btuh 52,000 70,000 70,000
Temperature rise range - °F 40 - 70 40 - 70 40 - 70
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10 3.5 / 10 3.5 / 10
Low
Fire
Input - Btuh 43,000 57,000 57,000
Output - Btuh 35,000 47,000 47,000
Temperature rise range - °F 25 -55 25 -55 25 -55
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.5 1.7 / 4.5 1.7 / 4.5
High static - in. w.g. Heating 0.8 0.8 0.8
Cooling 1.0 1.0 1.0
Connections
in.
Flue connection − in. round 4 4 4
Gas pipe size IPS 1/2 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 10 X 8 10 X 9 11-1/2 X 9
Motor output - hp 1/2 1/2 1.0
Tons of add-on cooling 2 - 3 2 - 3.5 2.5 - 4
Air Volume Range - cfm 606 - 1345 498 - 1393 679 - 2002
Electrical Data Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 7.7 7.7 12.8
Maximum overcurrent protection 15 15 20
Shipping Data lbs. - 1 package 128 143 154
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
2 Flue connection on the unit is 4 in. diameter. Most applications will require 5 in. venting and eld supplied 4 x 5 in. adaptor. See Venting Tables in the Installation
Instructions for detailed information.
SPECIFICATIONS
Gas
Heating
Performance
Model No. SL280UH090V60C SL280UH110V60C SL280UH135V60D
Model No. - Low Nox SL280UH090XV60C SL280UH110XV60C - - -
1 AFUE 80% 80% 80%
High
Fire
Input - Btuh 88,000 110,000 132,000
Output - Btuh 70,000 87,000 105,000
Temperature rise range - °F 35 - 65 35 - 65 40 - 70
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 57,000 72,000 86,000
Output - Btuh 47,000 58,000 69,000
Temperature rise range - °F 25 -55 25 -55 25 -55
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.5 1.7 / 4.5 1.7 / 4.5
High static - in. w.g. Heating 0.8 0.8 0.8
Cooling 1.0 1.0 1.0
Connections
in.
Flue connection − in. round 4 4 2 4
Gas pipe size IPS 1/2 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 11-1/2 X 10 11-1/2 X 10 11-1/2 X 11
Motor output - hp 1.0 1.0 1.0
Tons of add-on cooling 3 - 5 3 - 5 3.5 - 5
Air Volume Range - cfm 826 - 2305 812 - 2125 828 - 2257
Electrical Data Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 12.8 12.8 12.8
Maximum overcurrent protection 20 20 20
Shipping Data lbs. - 1 package 173 181 199
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization E󰀩ciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
2 Flue connection on the unit is 4 in. diameter. Most applications will require 5 in. venting and eld supplied 4 x 5 in. adaptor. See Venting Tables in the Installation
Instructions for detailed information.

Page 3
BLOWER DATA
SL280UH070V36A BLOWER PERFORMANCE (less lter)
BOTTOM RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1045 1145
+18% 985 1080
+12% 940 1035
+6% 880 960
Factory Default 850 925
–6% 785 875
–12% 745 815
–18% 680 745
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1045 1139 1219 1372
Factory Default 695 734 797 883 943 1005 1114 1260
–645 674 720 815 847 922 991 1144
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 250 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 250 cfm.
SL280UH070V36A BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 32 55 70 94 111 131 152 174 194 100 123 144 170 196 232 260 266 299 306 343
Med-Low 43 66 87 103 128 147 167 190 217 134 153 185 211 241 266 291 316 342 367 384
Med-High 53 74 97 120 143 165 184 209 228 181 198 234 261 289 316 342 367 390 411 436
High 77 101 123 148 175 194 218 242 266 259 282 318 339 375 402 430 457 489 507 536
Factory Default
Cooling
Speed
Low 26 44 61 78 94 114 138 152 163 66 86 112 139 160 174 199 223 247 270 296
Med-Low 27 49 66 83 106 126 147 169 182 87 107 134 158 182 206 232 258 274 302 319
Med-High 37 57 78 104 122 138 167 186 203 127 150 173 207 237 267 288 313 340 360 390
High 60 85 101 123 148 167 193 211 236 197 218 249 277 306 333 358 388 412 434 454
– Setting
Cooling
Speed
Low 19 34 54 69 86 105 119 144 149 45 66 91 105 138 150 176 189 213 237 266
Med-Low 23 41 56 75 90 112 132 144 159 61 86 103 132 150 172 193 217 233 262 291
Med-High 24 45 63 82 102 121 139 161 183 84 107 139 153 178 204 234 259 280 304 325
High 38 59 81 104 123 145 170 188 208 136 158 190 213 236 268 290 318 339 367 390

Page 4
BLOWER DATA
SL280UH070V36A BLOWER PERFORMANCE (less lter)
SINGLE SIDE RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1050 1165
+18% 1000 1110
+12% 940 1040
+6% 895 975
Factory Default 820 935
–6% 775 855
–12% 735 805
–18% 685 750
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1035 1122 1248 1360
Factory Default 704 725 793 899 949 1029 1135 1257
–642 680 717 812 874 933 1021 1133
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 250 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 250 cfm.
SL28UH070V36A BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 36 54 73 95 113 130 147 170 186 90 112 138 159 190 213 236 263 284 305 329
Med-Low 40 61 80 99 124 139 164 182 201 125 136 166 193 218 243 270 271 292 320 340
Med-High 52 74 98 116 140 162 182 207 226 163 181 217 246 274 311 331 358 382 410 430
High 77 100 123 144 165 187 213 234 259 236 259 290 327 354 381 413 448 467 496 519
Factory Default
Cooling
Speed
Low 22 42 63 74 98 119 135 158 174 68 90 107 134 157 175 202 222 239 260 286
Med-Low 30 49 68 83 111 126 139 160 184 86 109 135 153 178 204 232 258 273 292 321
Med-High 32 53 74 92 116 136 154 177 199 115 137 165 197 221 247 272 300 326 348 370
High 55 74 97 120 143 165 181 203 224 172 192 227 257 281 310 342 372 391 422 435
– Setting
Cooling
Speed
Low 17 31 48 69 82 97 111 131 146 48 67 89 110 129 152 172 194 215 231 251
Med-Low 22 43 57 74 84 109 130 140 163 62 84 103 124 151 173 196 212 233 258 277
Med-High 28 49 64 78 104 117 136 156 176 87 112 132 151 180 203 228 251 273 292 317
High 36 56 72 99 118 139 164 177 194 114 137 162 198 221 247 279 302 328 352 374

Page 5
BLOWER DATA
SL280UH090V36B BLOWER PERFORMANCE (less lter)
BOTTOM RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1300 1420
+18% 1250 1335
+12% 1185 1285
+6% 1145 1240
Factory Default 1070 1170
–6% 1015 1100
–12% 970 1035
–18% 880 980
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1018 1197 1291 1399
Factory Default 571 698 767 886 909 1083 1197 1284
–489 627 681 812 834 968 1081 1179
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 250 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 250 cfm.
SL280UH090V36B BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 13 29 43 62 73 86 105 122 137 63 85 105 134 159 186 207 230 252 275 292
Med-Low 27 46 64 84 102 119 137 159 177 112 136 157 193 224 247 277 300 321 350 372
Med-High 43 59 80 104 119 143 159 178 191 145 163 199 233 264 289 316 345 374 397 417
High 57 78 103 125 148 181 202 219 245 190 219 254 273 310 351 377 408 442 467 489
Factory Default
Cooling
Speed
Low 12 25 42 55 65 86 93 115 123 51 70 97 113 139 155 176 199 221 242 261
Med-Low 22 38 52 70 89 108 121 135 150 77 99 129 152 184 206 231 264 283 307 333
Med-High 27 46 64 85 103 123 141 157 179 112 136 157 193 224 247 277 300 321 350 372
High 51 68 90 110 136 150 172 198 211 145 164 197 232 257 290 320 351 362 396 411
– Setting
Cooling
Speed
Low 9 21 35 45 60 74 89 100 119 41 59 80 96 116 136 159 176 195 204 230
Med-Low 16 29 46 64 78 93 106 121 138 58 80 104 124 150 175 192 221 238 260 284
Med-High 22 40 54 68 90 108 125 141 153 73 94 125 152 177 203 228 258 279 304 326
High 36 53 72 91 112 131 150 169 185 99 125 154 182 207 234 266 296 320 344 369

Page 6
BLOWER DATA
SL280UH090V36B BLOWER PERFORMANCE (less lter)
SINGLE SIDE RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1305 1425
+18% 1250 1350
+12% 1195 1290
+6% 1135 1230
Factory Default 1070 1165
–6% 995 1100
–12% 935 1030
–18% 870 960
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1160 1274 1376
Factory Default 575 674 748 870 889 1075 1160 1270
–519 604 691 786 808 952 1056 1147
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 250 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 250 cfm.
SL280UH090V36B BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 10 27 41 57 72 88 105 123 135 55 82 99 123 148 173 199 220 244 266 290
Med-Low 23 44 59 80 99 119 138 158 177 103 129 151 184 214 235 264 290 316 342 368
Med-High 37 56 75 95 114 135 153 174 189 147 167 205 230 264 285 317 347 365 394 423
High 54 81 95 120 144 170 191 217 234 189 219 249 273 312 339 379 404 431 459 485
Factory Default
Cooling
Speed
Low 824 34 50 70 83 96 110 124 39 63 85 105 131 147 174 193 214 243 264
Med-Low 16 36 50 68 86 106 121 144 159 73 92 123 148 173 203 221 249 266 297 317
Med-High 23 43 61 81 106 123 144 160 182 103 129 151 184 214 235 264 290 316 342 368
High 43 62 88 107 123 145 169 189 209 149 170 199 234 259 291 311 334 367 389 412
– Setting
Cooling
Speed
Low 4 18 29 45 59 74 86 98 113 31 52 67 92 113 129 156 175 197 209 232
Med-Low 11 29 44 58 79 93 111 129 141 50 76 97 116 141 159 185 206 235 250 282
Med-High 15 36 52 67 86 108 126 144 161 68 89 121 139 167 192 219 243 269 292 310
High 32 53 70 94 109 129 153 174 189 95 118 144 178 198 226 256 278 302 328 352

Page 7
BLOWER DATA
SL280UH090V48B BLOWER PERFORMANCE (less lter)
BOTTOM RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1280 1410
+18% 1220 1340
+12% 1155 1270
+6% 1095 1205
Factory Default 1035 1135
–6% 970 1070
–12% 910 1000
–18% 845 930
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1030 1335 1550 1755
Factory Default 605 815 965 1090 940 1205 1405 1,600
–525 690 850 985 795 1060 1260 1435
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 380 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 380 cfm.
SL280UH090V48B BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 40 56 75 86 105 128 141 157 173 93 125 144 161 182 209 237 258 286 307 338
Med-Low 64 86 105 122 146 169 187 207 227 167 196 240 262 299 328 367 398 433 467 492
Med-High 93 119 141 163 189 213 237 261 286 259 287 321 374 410 451 481 518 555 581 611
High 128 156 188 219 248 281 308 338 366 372 407 465 493 558 604 661 706 726 764 817
Factory Default
Cooling
Speed
Low 35 51 64 79 92 107 122 138 159 81 105 122 139 159 186 200 221 247 263 286
Med-Low 50 65 85 114 130 148 173 179 200 112 142 173 206 234 271 300 323 356 395 419
Med-High 75 98 117 136 159 177 187 207 244 189 221 254 289 335 362 400 431 458 504 526
High 98 122 149 180 194 230 252 278 300 288 321 372 398 433 470 507 554 598 623 653
– Setting
Cooling
Speed
Low 32 44 57 71 82 95 107 121 132 74 94 112 130 147 174 189 206 226 245 264
Med-Low 43 60 76 91 109 127 143 159 176 86 119 134 161 185 212 236 257 290 320 342
Med-High 55 70 94 116 132 157 171 190 206 138 170 194 226 269 295 325 357 384 414 442
High 80 100 123 147 166 187 210 231 253 204 235 269 312 342 376 425 450 482 516 546

Page 8
BLOWER DATA
SL280UH090V48B BLOWER PERFORMANCE (less lter)
SINGLE SIDE RETURN AIR
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1280 1410
+18% 1220 1340
+12% 1155 1270
+6% 1095 1205
Factory Default 1035 1135
–6% 970 1070
–12% 910 1000
–18% 845 930
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1005 1295 1500 1670
Factory Default 570 780 930 1040 895 1160 1345 1500
–530 700 810 955 795 1050 1210 1405
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 380 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 380 cfm.
SL280UH090V48B BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 34 54 68 85 102 120 142 159 177 79 107 133 148 172 201 226 253 274 301 327
Med-Low 64 85 105 124 145 166 186 206 227 151 179 214 247 276 312 339 370 399 433 464
Med-High 85 112 135 157 184 208 233 258 284 230 261 305 348 379 421 453 490 523 565 602
High 110 139 172 201 234 270 294 326 352 478 369 414 462 506 547 597 643 691 735 781
Factory Default
Cooling
Speed
Low 30 46 59 77 87 106 118 143 152 70 93 115 134 153 172 195 219 242 260 286
Med-Low 36 56 76 95 120 136 162 175 196 100 132 163 192 214 244 276 307 338 368 402
Med-High 64 88 106 130 149 173 198 222 238 166 192 231 266 303 342 370 410 444 462 493
High 87 118 141 161 194 223 248 275 302 245 273 333 365 396 432 460 503 546 579 635
– Setting
Cooling
Speed
Low 28 43 53 70 83 97 110 120 135 53 72 88 112 133 150 175 191 205 230 245
Med-Low 37 56 72 86 106 124 141 158 176 84 111 134 154 185 215 235 260 284 311 336
Med-High 51 69 90 109 129 152 168 187 205 119 152 182 210 244 276 307 338 370 401 432
High 71 94 119 138 158 181 207 233 250 180 211 248 284 316 355 385 419 450 487 521

Page 9
BLOWER DATA
SL280UH090V48B BLOWER PERFORMANCE (less lter)
SIDE RETURN AIR WITH OPTIONAL RETURN AIR BASE
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1295 1425
+18% 1235 1355
+12% 1170 1290
+6% 1110 1220
Factory Default 1045 1150
–6% 980 1080
–12% 920 1010
–18% 855 945
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 985 1290 1495 1675
Factory Default 600 760 930 1045 905 1125 1345 1525
–535 700 850 970 815 1040 1225 1385
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 380 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 380 cfm.
SL280UH090V48B BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 34 54 65 84 101 122 138 156 169 75 104 128 146 170 193 224 244 266 300 326
Med-Low 57 74 97 120 137 158 177 197 216 124 160 189 216 254 287 319 351 385 416 449
Med-High 76 102 125 147 174 200 223 248 272 208 238 279 319 350 391 422 457 489 529 564
High 106 134 165 193 224 259 283 313 340 302 346 386 426 470 510 554 596 640 680 722
Factory Default
Cooling
Speed
Low 31 47 59 74 89 105 123 139 150 64 88 107 131 150 173 196 217 241 263 285
Med-Low 43 61 82 101 118 144 158 177 194 94 123 150 183 213 243 279 300 331 353 393
Med-High 62 85 104 130 151 173 196 216 239 150 180 219 250 294 333 368 399 428 463 497
High 81 113 131 151 187 211 238 264 291 235 263 312 349 387 426 455 489 522 568 608
– Setting
Cooling
Speed
Low 29 40 53 69 83 93 104 122 129 50 69 85 107 127 149 169 187 201 222 237
Med-Low 32 50 66 84 101 116 136 153 172 78 105 126 146 174 199 223 247 272 295 319
Med-High 46 65 86 109 127 146 167 187 207 105 135 166 195 227 262 289 319 348 380 411
High 69 92 112 134 156 175 200 221 245 161 195 230 264 298 334 367 401 434 469 503

Page 10
BLOWER DATA
SL280UH090V60C BLOWER PERFORMANCE (less lter)
BOTTOM RETURN AIR, RETURN AIR FROM BOTH SIDES OR RETURN AIR FROM BOTTOM AND ONE SIDE
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1420 1565
+18% 1355 1490
+12% 1285 1415
+6% 1215 1335
Factory Default 1145 1260
–6% 1080 1185
–12% 1010 1110
–18% 940 1035
COOLING
1Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2High Low Medium-Low Medium-High 2High
[phone] 1680 1575 1740 2000 2305
Factory Default 1005 1100 1280 1545 1440 1595 1820 2125
–890 1015 1125 1380 1295 1450 1610 1930
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch Settings.
2 Factory default setting.
NOTES - The e󰀨ect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28% and 38% of the selected second stage cooling speed - minimum 450 cfm.
Lennox iHarmony® Zoning System Applications - Minimum blower speed is 450 cfm.
SL280UH090V60C BLOWER MOTOR WATTS (COOLING)
1Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 89 113 136 159 182 204 228 251 275 218 245 291 327 372 398 436 474 505 532 579
Med-Low 104 133 163 184 214 245 266 304 328 298 333 382 412 450 488 541 576 612 648 681
Med-High 162 191 227 262 294 333 354 391 422 440 476 527 576 636 686 741 777 820 857 892
High 279 316 355 394 432 473 509 547 584 772 808 877 946 1000 1056 1089 1146 1190 1255 1266
Factory Default
Cooling
Speed
Low 70 92 108 134 159 174 196 215 242 160 195 228 265 291 340 364 397 442 469 500
Med-Low 89 115 135 156 185 207 227 250 281 241 267 305 347 384 413 445 477 519 542 573
Med-High 122 149 183 206 234 269 297 324 350 330 370 414 452 500 542 593 634 675 702 747
High 214 241 277 318 350 388 423 449 469 553 591 655 713 781 819 868 922 967 1026 1066
– Setting
Cooling
Speed
Low 54 70 91 110 129 154 166 185 200 107 151 177 206 245 272 298 332 398 423 449
Med-Low 73 94 112 135 151 175 189 214 235 173 201 244 272 304 337 368 393 437 465 498
Med-High 93 120 141 160 191 221 244 261 288 246 271 310 353 395 433 466 492 528 557 593
High 149 185 217 251 284 314 352 386 422 410 456 505 543 595 635 692 729 777 829 867