Lennox SLP99DFV Series User 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.
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.
WARNING
Electric shock hazard. Can cause injury or
death. Before attempting to perform any
service or maintenance, turn the electrical
power to unit OFF at disconnect switch(es).
Unit may have multiple power supplies.
SLP99DFV series units are high-e󰀩ciency downow gas
furnaces equipped with variable capacity gas valve, vari-
able speed combustion air inducer and variable speed
indoor blower motor. All models are designed for direct
vent (dual pipe) venting system only. SLP99DFV units are
available in heating capacities from 66,000 to 132,000
Btuh (19.3 to 38.6 kW) and cooling applications from 2 to
5 tons (7.0 kW to 17.5 kW). Refer to Engineering Hand-
book for proper sizing.
Units are factory-equipped for use with natural gas. Kits
are available for conversion to LP operation. SLP99DFV
models include a SureLight®variable integrated control
that can be used with a communication thermostat as part
of a communicating comfort system. All SLP99DFV units
meet the California Nitrogen Oxides (NOx) Standards and
California Seasonal E󰀩ciency requirements.
All specications in this manual are subject to change.
Procedures outlined in this manual are presented as rec-
ommendations only and do not supersede or replace local
or state codes. In the absence of local or state codes, the
guidelines and procedures outlined in this manual (except
where noted) are recommendations only and do not con-
stitute code.
TABLE OF CONTENTS
Specications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2
Optional Accessories . . . . . . . . . . . . . . . . . . . . . . Page 3
Blower Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4
I Unit Components . . . . . . . . . . . . . . . . . . . . . . . Page 10
II Communicating Thermostat . . . . . . . . . . . . . . Page 36
III Placement and Installation . . . . . . . . . . . . . . Page 39
IV Start Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 55
V Heating System Service Checks . . . . . . . . . . Page 56
VI Typical Operating Characteristics . . . . . . . . Page 62
VII Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . Page 62
VIII Wiring and Sequence of Operation . . . . . Page 65
IX Field Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 73
SLP99DFV
100002
10/2021
SLP99DFV SERIES UNITS

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. SLP99DF070XV36B SLP99DF090XV36C SLP99DF090XV48C
1AFUE 97.5% 97.5% 97.5%
Maximum Input - Btuh 66,000 88,000 88,000
Output - Btuh 64,000 84,000 85,000
Temperature rise range - °F 50 - 80 60 - 90 50 - 80
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0 3.5 / 10.0
Minimum Input - Btuh 23,000 31,000 31,000
Output - Btuh 22,000 30,000 30,000
Temperature rise range - °F 35 - 65 35 - 65 35 - 65
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
0.5 / 1.5 0.5 / 1.5 0.5 / 1.5
High static - in. w.g. 0.8 0.8 0.8
Connections
in.
Intake / ² Exhaust Pipe (PVC) 2 / 2 2 / 2 2 / 2
Gas pipe size IPS 1/2 1/2 1/2
Condensate Drain Trap (PVC pipe) - i.d. 3/4 3/4 3/4
with furnished 90° street elbow 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt
with eld supplied (PVC coupling) - o.d. 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT
Indoor
Blower
Wheel nominal diameter x width - in. 10 x 9 10 x 9 11 x 11
Motor output - hp 1/2 1/2 3/4
Tons of add-on cooling 2 - 3 2 - 3 3 - 4
Air Volume Range - cfm 410 - 1365 465 - 1385 545 - 1745
Electrical Data Voltage (Maximum Amps) 120 volts - 60 Hertz - 1 phase
Blower motor full load amps 7.7 7.7 10.1
Maximum overcurrent protection 15 15 15
Shipping Data lbs. - 1 package 141 156 166
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.
22 in. Rubber Flue Coupling is furnished for exhaust pipe connection to unit.
SPECIFICATIONS
Gas
Heating
Performance
Model No. SLP99DF090XV60C SLP99DF110XV60C
1AFUE 97.5% 97.5%
Maximum Input - Btuh 88,000 110,000
Output - Btuh 85,000 107,000
Temperature rise range - °F 50 - 80 50 - 80
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0
Minimum Input - Btuh 31,000 39,000
Output - Btuh 30,000 38,000
Temperature rise range - °F 35 - 65 35 - 65
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
0.5 / 1.5 0.5 / 1.5
High static - in. w.g. 0.8 0.8
Connections
in.
Intake / ² Exhaust Pipe (PVC) 2 / 2 2 / 2
Gas pipe size IPS 1/2 1/2
Condensate Drain Trap (PVC pipe) - i.d. 3/4 3/4
with furnished 90° street elbow 3/4 slip x 3/4 Mipt 3/4 slip x 3/4 Mipt
with eld supplied (PVC coupling) - o.d. 3/4 slip x 3/4 MPT 3/4 slip x 3/4 MPT
Indoor
Blower
Wheel nominal diameter x width - in. 11 x 11 11 x 11
Motor output - hp 1 1
Tons of add-on cooling 3.5 - 5 3.5 - 5
Air Volume Range - cfm 467 - 2130 575 - 2180
Electrical Data Voltage (Maximum Amps) 120 volts - 60 Hertz - 1 phase
Blower motor full load amps 12.8 12.8
Maximum overcurrent protection 20 20
Shipping Data lbs. - 1 package 166 175
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.
22 in. Rubber Flue Coupling is furnished for exhaust pipe connection to unit.

Page 3
OPTIONAL ACCESSORIES - ORDER SEPARATELY
NOTE - FURNACES CANNOT BE TWINNED!
“B” Width Models “C” Width Models
CABINET ACCESSORIES
Downow Combustible Flooring Base 11M60 11M61
High Performance Economizer (Commercial Only) 10U53 10U53
CONDENSATE DRAIN KITS
Condensate Drain Heat Cable 6 ft. 26K68 26K68
24 ft. 26K69 26K69
Crawl Space Vent Drain Kit US 51W18 51W18
Canada 15Z70 15Z70
CONTROLS
iComfort®S30 Ultra-Smart Wi-Fi Thermostat 12U67 12U67
1Remote Outdoor Temperature Sensor X2658 X2658
Night Service Kit 20F44 20F44
DOWNFLOW FILTER KITS
Downow Air Filter and Rack Kit 51W07 51W08
No. and Size of lter - in. (2) 16 x 20 x 1 (2) 16 x 20 x 1
TERMINATION KITS
Direct Vent Applications Only. See Installation Instructions for specic venting information.
Direct Vent Concentric US - 2 in. 71M80 69M29
3 in. - - - 60L46
Canada - 2 in. 44W92 44W92
3 in. - - - 44W93
Flush-Mount US - 2, 2-1/2 or 3 in. 51W11 51W11
Canada - 2, 2-1/2 or 3 in. 51W12 51W12
Wall - Close Couple US - 2 in. 22G44 - - -
3 in. 44J40 44J40
Wall - Close
Couple WTK
Canada - 2 in. 30G28 - - -
3 in. 81J20 81J20
Roof Termination Flashing Kit
(no vent pipe - 2 ashings)
2 in. 15F75 15F75
3 in. 44J41 44J41
VENTING
2Left Side Vent Kit 2 or 3 in. 87W73 87W73
1Remote Outdoor Temperature Sensor is used with conventional (non-iComfort®Communicating) outdoor units (sensor is furnished with iComfort®Communicating
outdoor units). Allows the thermostat to display outdoor temperature. Required in dual-fuel and EDA applications.
2NOTE - The curved exhaust pipe furnished with the Left Side Vent Kit counts as one additional 2 in. diameter 90° elbow. When using 3 in. diameter pipe, the furnished
curved exhaust pipe and eld provided ttings to transition from 2 in. to 3 in. count as 20 feet of equivalent pipe on all units.
NOTE - Termination Kits (44W92, 44W93, 30G28, 51W12, 81J20) and Crawl Space Vent Drain Kit (15Z70) are certied to ULC S636 standard for use in Canada only.

Page 4
BLOWER DATA
SLP99DF070XV36B BLOWER PERFORMANCE (less lter)
HEATING BLOWER PERFORMANCE - 0 through 0.8 in. w.g. External Static Pressure Range
Heating Adjust CFM Selections Heating Input Range and Blower Volume - CFM
35% 40% 50% 60% 70% 80% 90% 100%
Increase (+15%) Heat CFM 495 543 639 735 830 926 1022 1118
Increase (+7.5%) Heat CFM 473 516 604 691 778 866 953 1041
Default Heat CFM 450 489 568 647 726 805 884 963
Decrease (-7.5% ) Heat CFM 430 467 540 614 687 761 834 908
Decrease (-15% ) Heat CFM 410 444 512 580 649 717 785 853
COOLING BLOWER PERFORMANCE - 0 through 1.0 in. w.g. External Static Pressure Range
Cooling Adjust CFM
Selections
Blower Speed Selections
First Stage Cool Speed - cfm Second Stage Cool Speed - cfm
Low Medium-
Low
Medium
High
High
(Default)
Low Medium-
Low
Medium
High
High
(Default)
Increase (+10%) Cool CFM 625 785 890 995 910 1075 1230 1365
Default Cool CFM 575 710 830 890 845 960 1125 1265
Decrease (-10%) Cool CFM 520 615 710 820 755 885 985 1150
The e󰀨ect of static pressure is included in air volumes shown.
The following control congurations are available. See Installation Instructions for details and DIP switch settings.
Heat Modes Available (Heating Blower Performance Table):
Single-stage thermostat:
- 35%, 70%, 100% input (three-stage) with time delays in-between
Two-stage thermostat:
- Variable Rate Capacity Mode - furnace automatically adjusts ring rate based on rst- and second-stage cycle times.
- W1 demand at 70% input, W2 demand at 100% input. No delay between stages.
Cool Mode Available (Cooling Blower Performance Table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position minimum 250 cfm.
Lennox iHarmony®Zoning System Applications - Minimum blower speed is 250 cfm.
SLP99DF070XV36B BLOWER MOTOR WATTS - COOLING
Blower Speed
Options
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
Increase (+10%) Cool CFM
Low 20 37 57 71 90 108 128 142 162 67 90 110 136 159 184 200 226 252 271 292
Medium-Low 36 59 77 96 125 145 166 187 203 113 136 164 188 223 256 276 309 332 354 367
Medium-High 59 82 104 132 151 178 199 222 244 185 199 239 270 297 331 356 393 411 430 441
High 83 107 135 158 185 213 247 258 286 279 292 323 359 387 417 445 475 500 515 509
Default Cool CFM
Low 18 29 51 66 83 98 111 127 143 48 66 84 118 141 164 185 203 226 243 260
Medium-Low 27 50 64 84 105 124 146 162 185 89 109 142 160 188 211 240 262 286 312 327
Medium-High 39 60 81 109 136 162 183 194 220 126 145 183 209 244 272 301 330 358 378 401
High 65 82 112 144 164 185 207 227 257 209 218 261 292 320 352 384 400 424 448 462
Decrease (-10%) Cool CFM
Low 11 28 39 57 74 89 102 116 137 36 55 74 91 120 137 160 183 198 213 233
Medium-Low 23 37 57 77 92 112 128 143 156 63 83 105 132 162 181 208 227 251 268 291
Medium-High 32 54 70 87 113 133 149 172 189 90 112 144 164 200 216 246 275 303 326 342
High 47 67 91 115 139 163 184 203 224 134 151 192 222 255 287 320 348 370 395 414

Page 5
BLOWER DATA
SLP99DF090XV36C BLOWER PERFORMANCE (less lter)
HEATING BLOWER PERFORMANCE - 0 through 0.8 in. w.g. External Static Pressure Range
Heating Adjust CFM Selections Heating Input Range and Blower Volume - CFM
35% 40% 50% 60% 70% 80% 90% 100%
Increase (+15%) Heat CFM 710 756 848 940 1033 1125 1217 1309
Increase (+7.5%) Heat CFM 670 713 799 885 971 1057 1143 1230
Default Heat CFM 629 669 749 829 910 990 1070 1150
Decrease (-7.5% ) Heat CFM 559 599 681 763 845 927 1009 1091
Decrease (-15% ) Heat CFM 488 530 614 697 781 865 948 1032
COOLING BLOWER PERFORMANCE - 0 through 1.0 in. w.g. External Static Pressure Range
Cooling Adjust CFM
Selections
Blower Speed Selections
First Stage Cool Speed - cfm Second Stage Cool Speed - cfm
Low Medium-
Low
Medium
High
High
(Default)
Low Medium-
Low
Medium
High
High
(Default)
Increase (+10%) Cool CFM 610 770 900 1035 920 1080 1215 1385
Default Cool CFM 545 690 805 920 835 1000 1135 1255
Decrease (-10%) Cool CFM 465 620 720 810 750 890 1025 1145
The e󰀨ect of static pressure is included in air volumes shown.
The following control congurations are available. See Installation Instructions for details and DIP switch settings.
Heat Modes Available (Heating Blower Performance Table):
Single-stage thermostat:
- 35%, 70%, 100% input (three-stage) with time delays in-between
Two-stage thermostat:
- Variable Rate Capacity Mode - furnace automatically adjusts ring rate based on rst- and second-stage cycle times.
- W1 demand at 70% input, W2 demand at 100% input. No delay between stages.
Cool Mode Available (Cooling Blower Performance Table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position minimum 250 cfm.
Lennox iHarmony®Zoning System Applications - Minimum blower speed is 250 cfm.
SLP99DF090XV36C BLOWER MOTOR WATTS - COOLING
Blower Speed
Options
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
Increase (+10%) Cool CFM
Low 21 33 51 67 82 94 111 124 139 54 77 102 117 151 173 191 216 239 262 283
Medium-Low 40 60 80 92 114 130 150 170 190 111 130 152 183 209 231 256 278 296 324 338
Medium-High 59 80 103 126 152 173 194 220 234 160 180 216 240 261 293 318 339 374 392 419
High 76 102 121 160 178 208 229 251 283 223 247 268 319 350 384 411 456 460 497 511
Default Cool CFM
Low 16 29 41 59 72 84 98 112 123 46 69 84 106 132 142 170 194 211 232 248
Medium-Low 33 47 67 81 95 116 128 145 161 82 98 127 153 174 200 218 244 264 285 303
Medium-High 47 69 84 106 128 145 163 184 207 121 137 167 201 225 252 273 291 306 339 370
High 57 78 101 130 150 176 195 220 238 168 194 226 248 276 315 340 367 400 418 441
Decrease (-10%) Cool CFM
Low 10 24 34 47 59 73 86 96 109 37 57 74 88 102 121 140 161 172 193 212
Medium-Low 23 36 56 69 82 99 113 129 143 50 70 89 111 137 158 182 197 221 234 259
Medium-High 37 52 71 88 102 120 139 153 170 82 104 124 154 181 207 227 253 275 294 316
High 46 68 83 106 125 137 167 182 204 136 158 178 210 242 255 282 299 327 357 374

Page 6
BLOWER DATA
SLP99DF090XV48C BLOWER PERFORMANCE (less lter)
HEATING BLOWER PERFORMANCE - 0 through 0.8 in. w.g. External Static Pressure Range
Heating Adjust CFM Selections Heating Input Range and Blower Volume - CFM
35% 40% 50% 60% 70% 80% 90% 100%
Increase (+15%) Heat CFM 723 790 925 1060 1195 1329 1464 1599
Increase (+7.5%) Heat CFM 690 752 878 1004 1129 1255 1381 1507
Default Heat CFM 656 714 831 948 1064 1181 1297 1414
Decrease (-7.5% ) Heat CFM 601 654 761 867 974 1081 1188 1295
Decrease (-15% ) Heat CFM 545 593 690 787 884 981 1078 1175
The e󰀨ect of static pressure is included in air volumes shown.
The following control congurations are available. See Installation Instructions for details and DIP switch settings.
Heat Modes Available (Heating Blower Performance Table):
Single-stage thermostat:
- 35%, 70%, 100% input (three-stage) with time delays in-between
Two-stage thermostat:
- Variable Rate Capacity Mode - furnace automatically adjusts ring rate based on rst- and second-stage cycle times.
- W1 demand at 70% input, W2 demand at 100% input. No delay between stages.
Cool Mode Available (Cooling Blower Performance Table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position minimum 250 cfm.
Lennox iHarmony®Zoning System Applications - Minimum blower speed is 380 cfm.
COOLING BLOWER PERFORMANCE - 0 through 1.0 in. w.g. External Static Pressure Range
Cooling Adjust CFM
Selections
Blower Speed Selections
First Stage Cool Speed - cfm Second Stage Cool Speed - cfm
Low Medium-
Low
Medium
High
High
(Default)
Low Medium-
Low
Medium
High
High
(Default)
Increase (+10%) Cool CFM 775 940 1100 1255 1120 1340 1535 1745
Default Cool CFM 690 875 975 1135 1000 1220 1425 1625
Decrease (-10%) Cool CFM 635 755 915 1025 920 1100 1270 1470
SLP99DF090XV48C BLOWER MOTOR WATTS - COOLING
Blower Speed
Options
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
Increase (+10%) Cool CFM
Low 34 62 76 98 125 146 175 197 213 83 118 153 178 210 243 273 320 347 380 408
Medium-Low 52 80 102 134 167 188 211 242 267 132 162 217 252 316 339 384 435 465 502 541
Medium-High 70 106 135 174 200 235 268 309 336 242 279 329 376 426 464 497 547 601 643 673
High 105 147 182 218 267 303 341 395 412 350 397 443 515 559 619 681 739 770 813 869
Default Cool CFM
Low 30 51 67 92 107 131 145 165 192 55 83 114 147 181 204 241 261 290 324 360
Medium-Low 39 67 89 115 139 170 194 224 242 99 142 166 212 243 289 333 367 399 432 473
Medium-High 61 91 116 142 176 198 219 261 283 174 193 264 304 350 387 434 478 517 549 575
High 79 112 154 179 221 247 292 326 354 265 312 357 411 439 516 540 596 649 685 730
Decrease (-10%) Cool CFM
Low 25 43 58 80 100 113 136 152 166 48 72 101 123 151 181 198 229 256 283 300
Medium-Low 36 59 82 102 123 142 173 196 210 73 106 144 172 204 234 268 311 345 370 405
Medium-High 41 68 90 117 149 178 199 225 247 105 146 172 217 262 308 353 388 417 459 487
High 61 93 118 150 181 205 239 266 302 204 228 276 331 391 422 458 492 530 566 609

Page 7
BLOWER DATA
SLP99DF090XV60C BLOWER PERFORMANCE (less lter)
HEATING BLOWER PERFORMANCE - 0 through 0.8 in. w.g. External Static Pressure Range
Heating Adjust CFM Selections Heating Input Range and Blower Volume - CFM
35% 40% 50% 60% 70% 80% 90% 100%
Increase (+15%) Heat CFM 653 728 877 1027 1176 1326 1475 1625
Increase (+7.5%) Heat CFM 603 673 813 953 1092 1232 1372 1512
Default Heat CFM 553 618 748 878 1009 1139 1269 1399
Decrease (-7.5% ) Heat CFM 510 570 690 811 931 1051 1171 1292
Decrease (-15% ) Heat CFM 467 522 632 743 853 963 1074 1184
The e󰀨ect of static pressure is included in air volumes shown.
The following control congurations are available. See Installation Instructions for details and DIP switch settings.
Heat Modes Available (Heating Blower Performance Table):
Single-stage thermostat:
- 35%, 70%, 100% input (three-stage) with time delays in-between
Two-stage thermostat:
- Variable Rate Capacity Mode - furnace automatically adjusts ring rate based on rst- and second-stage cycle times.
- W1 demand at 70% input, W2 demand at 100% input. No delay between stages.
Cool Mode Available (Cooling Blower Performance Table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position minimum 250 cfm.
Lennox iHarmony®Zoning System Applications - Minimum blower speed is 450 cfm.
COOLING BLOWER PERFORMANCE - 0 through 1.0 in. w.g. External Static Pressure Range
Cooling Adjust CFM
Selections
Blower Speed Selections
First Stage Cool Speed - cfm Second Stage Cool Speed - cfm
Low Medium-
Low
Medium
High
High
(Default)
Low Medium-
Low
Medium
High
High
(Default)
Increase (+10%) Cool CFM 1110 1265 1395 1600 1600 1750 1965 2130
Default Cool CFM 1000 1145 1275 1445 1445 1625 1805 1975
Decrease (-10%) Cool CFM 885 1060 1145 1265 1265 1445 1645 1805
SLP99DF090XV60C BLOWER MOTOR WATTS - COOLING
Blower Speed
Options
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
Increase (+10%) Cool CFM
Low 79 108 144 162 207 242 262 293 323 275 299 366 399 449 483 532 584 605 644 680
Medium-Low 120 156 187 233 261 279 329 368 401 387 409 471 521 562 606 650 688 716 762 800
Medium-High 155 202 235 293 317 369 407 453 502 547 577 622 667 744 795 835 872 910 950 963
High 268 299 366 399 449 483 532 584 605 780 775 811 898 942 994 1048 1071 1082 1080 1073
Default Cool CFM
Low 56 86 111 140 170 200 232 259 282 186 219 270 308 361 390 431 489 517 555 590
Medium-Low 93 118 152 195 223 254 283 306 344 278 304 365 420 450 510 544 592 640 665 698
Medium-High 123 161 201 228 260 310 341 381 416 446 475 528 582 616 662 686 747 780 823 855
High 182 219 270 308 361 390 431 489 517 576 603 654 704 756 809 871 902 939 972 975
Decrease (-10%) Cool CFM
Low 48 69 101 120 152 175 201 218 249 118 155 181 232 259 299 340 376 402 438 476
Medium-Low 65 94 123 150 185 220 250 278 296 177 205 267 304 353 390 430 486 515 563 587
Medium-High 93 118 152 195 223 254 283 306 344 301 322 392 439 468 531 568 599 647 678 721
High 116 155 181 232 259 299 340 376 402 446 475 528 582 616 662 686 747 780 823 855

Page 8
BLOWER DATA
SLP99DF110XV60C BLOWER PERFORMANCE (less lter)
HEATING BLOWER PERFORMANCE - 0 through 0.8 in. w.g. External Static Pressure Range
Heating Adjust CFM Selections Heating Input Range and Blower Volume - CFM
35% 40% 50% 60% 70% 80% 90% 100%
Increase (+15%) Heat CFM 811 906 1096 1286 1475 1665 1855 2045
Increase (+7.5%) Heat CFM 744 835 1017 1199 1380 1562 1744 1926
Default Heat CFM 677 764 938 1112 1285 1459 1633 1807
Decrease (-7.5% ) Heat CFM 626 707 869 1031 1193 1355 1517 1679
Decrease (-15% ) Heat CFM 575 650 800 950 1101 1251 1401 1551
The e󰀨ect of static pressure is included in air volumes shown.
The following control congurations are available. See Installation Instructions for details and DIP switch settings.
Heat Modes Available (Heating Blower Performance Table):
Single-stage thermostat:
- 35%, 70%, 100% input (three-stage) with time delays in-between
Two-stage thermostat:
- Variable Rate Capacity Mode - furnace automatically adjusts ring rate based on rst- and second-stage cycle times.
- W1 demand at 70% input, W2 demand at 100% input. No delay between stages.
Cool Mode Available (Cooling Blower Performance Table):
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan speeds are approximately 28% and 38% (DIP switch selectable) of the same second-stage COOL speed position minimum 250 cfm.
Lennox iHarmony®Zoning System Applications - Minimum blower speed is 450 cfm.
COOLING BLOWER PERFORMANCE - 0 through 1.0 in. w.g. External Static Pressure Range
Cooling Adjust CFM
Selections
Blower Speed Selections
First Stage Cool Speed - cfm Second Stage Cool Speed - cfm
Low Medium-
Low
Medium
High
High
(Default)
Low Medium-
Low
Medium
High
High
(Default)
Increase (+10%) Cool CFM 1090 1260 1395 1580 1580 1790 1990 2180
Default Cool CFM 965 1125 1285 1440 1440 1625 1845 2000
Decrease (-10%) Cool CFM 860 1030 1125 1270 1270 1470 1655 1845
SLP99DF110XV60C BLOWER MOTOR WATTS - COOLING
Blower Speed
Options
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
Increase (+10%) Cool CFM
Low 71 99 147 166 202 240 271 302 337 248 280 333 374 429 469 511 548 594 619 677
Medium-Low 127 159 198 225 256 301 325 365 390 409 427 496 531 587 632 665 721 742 781 805
Medium-High 162 204 242 287 316 371 408 446 487 563 589 651 703 755 808 860 888 932 970 1007
High 243 280 333 374 429 469 511 548 594 866 850 915 963 1020 1056 1091 1127 1141 1136 1131
Default Cool CFM
Low 57 88 117 140 165 196 232 259 283 167 214 244 291 331 380 405 467 497 539 583
Medium-Low 77 112 147 172 209 250 283 317 345 275 321 348 418 447 505 546 597 632 668 716
Medium-High 122 154 199 230 268 300 331 373 411 461 493 547 572 628 666 703 745 777 819 860
High 167 214 244 291 331 380 405 467 497 601 626 688 730 787 823 880 924 963 994 1011
Decrease (-10%) Cool CFM
Low 44 67 99 115 144 167 197 215 245 126 165 201 232 262 305 334 373 417 451 479
Medium-Low 66 97 123 153 186 216 247 275 303 187 219 272 308 360 391 432 479 514 559 588
Medium-High 77 112 147 172 209 250 283 317 345 308 341 390 430 490 528 569 617 640 691 724
High 127 165 201 232 262 305 334 373 417 461 493 547 572 628 666 703 745 777 819 860

Page 9
Parts Arrangement
BURNER BOX ASSEMBLY
GAS VALVE
ACCESS PANEL
COMBUSTION AIR INDUCER
BLOWER
ACCESS
PANEL
BLOWER ASSEMBLY
(Variable Speed Blower
Motor Is Hidden)
BAG ASSEMBLY
CONTROL BOX
(includes variable capacity
integrated control,
transformer, circuit breaker
and door switch)
PRIMARY LIMIT
SIDE VENT
PATCH PLATE
FIGURE 1

Page 10
I-UNIT COMPONENTS
SLP99DFV unit components are shown in FIGURE 1. The
gas valve, combustion air inducer and burners can be
accessed by removing the access panel. Electrical com-
ponents are in the control box (FIGURE 2) found in the
blower compartment.
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
CAUTION
Electrostatic discharge can a󰀨ect
electronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
A-Control Box
1. Control Transformer (T1)
A transformer located in the control box provides power
to the low voltage section of the unit. Transformers on all
models are rated 40VA with a 120V primary and a 24V
secondary.
2. Interlock Switch (S51)
An interlock switch rated 14A at 125VAC is wired in series
with line voltage. When the inner blower access panel is
removed the unit will shut down.
CONTROL BOX
SURELIGHT®
INTEGRATED
CONTROL TRANSFORMER
CIRCUIT
BREAKER
DOOR
INTERLOCK
SWITCH
FIGURE 2
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated 3A at 32V. If the current exceeds
this limit the breaker will trip and all unit operation will shut
down. The breaker can be manually reset by pressing the
button on the face. See FIGURE 3.
CIRCUIT BREAKER CB8
PRESS TO RESET
FIGURE 3
WARNING
Shock hazard.
Disconnect power before servicing.
Integrated control is not eld repairable. If control is
inoperable, simply replace entire control.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
4. Integrated Control (A92)
SLP99DFV units are equipped with the Lennox SureLight®
variable-capacity integrated control. This control can be
used with a communicating thermostat as part of a com-
municating system. The control can also operate with a
conventional single or two-stage thermostat. The system
consists of an ignition / blower control (FIGURE 4 and
FIGURE 5) with control pin designations in TABLE 1, TA-
BLE 2 and ignitor. The control provides gas ignition, safety
checks and indoor blower control with variable capacity
rate gas heating. The furnace combustion air inducer, gas
valve and indoor blower are controlled in response to vari-
ous system inputs such as thermostat signal, pressure and
limit switch signal and ame signal. The control features a
seven-segment LEDdisplay, indicating furnace status (in-
cluding indoor blower) and error codes. The LED ashes
in single digits. For example using table 14 under LIMIT
CODE, an “E” followed by “2” followed by “5” followed by
“0”, the limit switch circuit is open. The control also has
two 120 volt accessory terminals (used for a humidier
and electronic air cleaner) rated at (1) one amp each.