Lennox LDT Series Owner's manual

100083
LDT SERIES
Service Literature
13 to 20 ton
LDT156 through 240
The LDT156, 180 and 240 units are configure to order units
(CTO) with a wide selection of factory installed options.
The LDT156 is available in 169,000 to 360,000 Btuh. The
LDT180/240 is available in 169,000 to 480,000 Btuh..
Gas heat sections are designed with stainless steel tube
heat exchangers with stainless steel as an option.
Cooling capacities range from 13 to 20 tons. The LDT 156,
180 & 240 utilize two compressors and six condenser fans.
Multi-Stage Air Volume MSAV®blower option is available.
The VFD-driven blower will operate at lower speeds when
demand is low and increase to higher speeds when
demand is high.
All LDT units are designed to accept any of several different
energy management thermostat control systems with
minimum field wiring. Factory- or field-provided control
options connect to the unit through Smartwiret
connectors. When "plugged in" the controls become an
integral part of the unit wiring.
The CORE Control System is designed to accelerate
equipment install and service. Standard with all Enlight
rooftop units, control system integrates key technologies
that lower installation costs, drive system efficiency, and
protect your investments.
The CORE Unit Controller is a microprocessor-based
controller that provides flexible control of all unit functions.
Information contained in this manual is intended for use by
qualified service technicians only. All specifications are
subject to change. Procedures outlined in this manual are
presented as a recommendation only and do not
supersede or replace local or state codes.
If the unit must be lifted for service, rig unit by attaching four
cables to the holes located in the unit base rail (two holes at
each corner). Refer to the installation instructions for the
proper rigging technique.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person
al injury or loss of life. Installation and service must
be performed by a qualified installer or service
agency.
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 per
forming maintenance.
3- Always keep hands, hair, clothing, jewelery, tools,
etc.,c away from moving parts.
Table of Contents
Options / Accessories Page 2.....................
Specifications Page 6............................
Gas Heat Specifications / High Altitude Page 7......
Blower Data Page 8.............................
Electrical Data Page 11...........................
Unit Parts Arrangement Page 13...................
I-Unit Components Page 13.......................
II-Placement and Installation Page 31...............
III-Charging Page 31..............................
IV Start Up - Operation Page 32....................
V-System Service Checks Page 34.................
VI-Maintenance Page 36.........................
VII-Accessories Page 37..........................
VIII-Staged Blower Page 42.......................
IX-Wiring and Operation Sequence Page 45.........

Page 2
OPTIONS / ACCESSORIES
Item Description Catalog
Number
Unit Model No
156 180 240
COOLING SYSTEM
Condensate Drain Trap PVC 22H54 XXX
Copper 76W27 XXX
Conventional Fin/Tube Condenser Coil Factory O O O
 21Z07 OX OX OX
Refrigerant Type R-410A O O O
HEATING SYSTEM
Bottom Gas Piping Kit 85M31 XXX
 89L97 XXX
Gas Heat Input  Factory O O
 Factory O O O
 Factory O O O
 Factory O O
  22H58 XXX
 22H59 XXX
 13X68 XXX
LPG/Propane Conversion Kits

 14N28 X X
 14N28 XXX
Medium Heat 14N29 XXX
 14N30 XXX
 42W16 XXX
BLOWER - SUPPLY AIR
 ® Factory O O
® Factory O O O
Motors  Factory O O
 Factory O O O
 Factory O O
 Factory O
Drive Kits

selection
Kit #1 535-725 rpm Factory O O
 Factory O O
 Factory O O O
Kit #4 850-1045 rpm Factory O O O
 Factory O O O
 Factory O O
 Factory O O
Kit #8 1045-1285 rpm Factory O O
Kit #10 1045-1285 rpm Factory O
 Factory O
 24B80 XXX
CABINET
Combination Coil/Hail Guards 23U71 OX OX OX
Corrosion Protection Factory O O O



X = Field Installed

Page 3
OPTIONS / ACCESSORIES
Item Description Catalog
Number
Unit Model No
156 180 240
CONTROLS
 21Z10 OX OX OX
Commercial Controls CPC Einstein Integration Factory O O O
LonTalk®Module 54W27 OX OX OX
Novar®  Factory O O O
 53W68 OX OX OX
 21Z08 OX OX OX
 22H56 OX OX OX
 22H57 OX OX OX
INDOOR AIR QUALITY
Air Filters
®󰀩

MERV 8 54W67 OX OX OX
MERV 13 52W40 OX OX OX
 21U42 XXX


44N61 XXX

󰀨 77N39 XXX
󰀨 23V86 XXX
 87N52 XXX
 87N54 XXX
CO 85L43 XXX
Aspiration Box - for duct mounting non-plenum rated CO2 sensors (77N3990N43 XXX

 21U37 X X
21U38 X
UVC Germicidal Light Kit
1® 21A94 XXX
  10H20 XXX
 10H21 XXX
ELECTRICAL
  Factory O O O
 Factory O O O
 Factory O O O
HACR Circuit Breakers Factory O O O
 Factory O O O


80 amp 54W88 OX OX OX
150 amp 54W89 OX OX OX
250 amp 90W82 OX OX OX

Outlets
 74M70 OX OX OX
 Factory O O O
 67E01 XXX
³  Factory O O O
 10C89 XXX
1

2
3



X = Field Installed

Page 4
OPTIONS / ACCESSORIES
Item Description Catalog
Number
Unit Model No
156 180 240
ECONOMIZER




23G24 OX OX OX
Economizer Controls
󰀨 Order 2 21Z09 OX OX OX
  Factory O O O
 21Z09 OX OX OX
Global Control  Factory O O O
Building Pressure Control 13J77 XXX
Outdoor Air CFM Control 13J76 XXX
Barometric Relief Dampers With Exhaust Hood
 54W78 OX OX OX
Horizontal Barometric Relief Dampers 16K99 XXX
OUTDOOR AIR
Outdoor Air Dampers With Outdoor Air Hood
Motorized 22J27 OX OX OX
Manual 13U05 XXX
¹ POWER EXHAUST (DOWNFLOW APPLICATIONS ONLY)
 208/230V 22H90 OX OX OX
 22H91 OX OX OX
575V 22V34 OX OX OX
1and



X = Field Installed

Page 5
OPTIONS / ACCESSORIES
Item Description Catalog
Number
Unit Model No
156 180 240
ROOF CURBS

 11F58 XXX
 11F59 XXX
 11F60 XXX
 11F61 XXX
Adjustable Pitch Curb
 43W26 XXX
Standard Roof Curbs, Horizontal - Requires Horizontal Return Air Panel Kit
 11T89 XXX
 11T96 XXX
Insulation Kit For Standard Horizontal Roof Curbs
 73K32 XXX
For 37 in. Curb 73K34 XXX
Horizontal Return Air Panel Kit
 87M00 XXX
CEILING DIFFUSERS
  13K63 X X
 13K64 X
  13K58 X X
 13K59 X
 C1DIFF33C-1 12X68 X X
C1DIFF34C-1 12X70 X



X = Field Installed


SPECIFICATIONS
General Data Nominal Tonnage 13 Ton 15 Ton 20 Ton
Model Number LDT156H4M LDT180H4M LDT240H4M
󰀩 High High High
Blower Type ®

®

®

Cooling
Performance
   
1   
1  4500 5500 7000
   20.5
1 15.5 15.3 15.3
1   
Refrigerant
Charge
Refrigerant Type R-410A R-410A R-410A
Circuit 1 21 lbs. 0 oz. 22 lbs. 12 oz. 22 lbs. 8 oz.
Circuit 2 21 lbs. 0 oz. 21 lbs. 12 oz. 21 lbs. 8 oz.
Heating
Performance
1   
 12.4 14.8 
1C.O.P. 3.40 3.40 3.40
1   
 11.1 13.3 17.8
1C.O.P. 2.10 2.10 2.10
Gas Heating Options Available
   
Outdoor Coils  55.1 55.1 55.1
 222
 20 20 20
Outdoor Coil
Fans
   
Motor rpm 1075 1075 1075
 2150 2150 2150
   
Number of blades 3 3 3
Total Air volume - cfm   
Indoor Coils  21.4 21.4 21.4
Tube diameter - in. 3/8 3/8 3/8
 444
 14 14 14
Drain connection - No. and size   
Expansion device type 
2Indoor
Blower
and
Drive
Selection
Nominal motor output   
   
Motor - Drive kit number 
Kit 1 535-725 rpm



Kit 4 850-1045 rpm


Kit 1 535-725 rpm



Kit 4 850-1045 rpm




Kit 8 1045-1285 rpm


Kit 4 850-1045 rpm




Kit 8 1045-1285 rpm


Kit 10 1045-1285 rpm

   
Filters  
Number and size - in. 
Electrical characteristics 

1
Cooling Ratings
High Temperature Heating Ratings
Low Temperature Heating Ratings
2


NOTE – Motor service factor limit - 1.0.

Page 7
SPECIFICATIONS GAS HEAT
Usage Data Model Number LDT156
LDT180
LDT156
LDT180
LDT240
LDT180
LDT240
Heat Input Type    
 One   
¹ Gas Heating
Performance
     
 - - -   
 - - -   
 - - -   
   - - - - - - - - -
 - - - - - - - - - - - -
 - - - - - - - - - - - -
 - - -   
  15-45 15-45  40-70
 - - - - - - - - - - - -
Minimum Air Volume - cfm 4500 4500 4500 5125
󰀩 80% 81% 81% 81%
 1 in. NPT 1 in. NPT 1 in. NPT 1 in. NPT


Natural 7 7 7 7
LPG/Propane 11 11 11 11

Pressure Range
 
 
1
®

HIGH ALTITUDE DERATE
NOTE - Units may be installed at altitudes up to 2000 feet above sea level without any modication.
At altitudes above 2000 feet, units must be derated to match gas manifold pressures shown in table below.
At altitudes above 4500 feet units must be derated 4% for each 1000 feet above sea level.
NOTE − This is the only permissible derate for these units.
Refer to the Installation Instructions for more detailed information.
ONE STAGE HEAT
No Adjustment Required
TWO STAGE HEAT
Heat Input Type Altitude Feet Gas Manifold Pressure - in. w.g. 
Natural Gas LPG/Propane Gas First Stage Second Stage
 2001 - 4500    
 2001 - 4500    
 2001 - 4500    
FOUR STAGE HEAT
¹ Heat Input Type Altitude Feet
Gas Manifold Pressure - in. w.g. 
Natural Gas LPG/Propane Gas First
Stage
Second
Stage
Third
Stage
Fourth
Stage
 2001 - 4500      
 2001 - 4500      
 2001 - 4500      
1

Page 8
BLOWER DATA
  1 - Wet indoor coil air resistance of selected unit.  󰀨   󰀨 
Air Volume
cfm

0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60
RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP RPM BHP
2750 385 0.30 505 0.50  0.70   755 1.10 820 1.30 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3000  0.35 515 0.55  0.75  1.00  1.20 825 1.45 885 1.70 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3250 405 0.40 520   0.85  1.10  1.30 830   1.85  2.10 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
3500 415 0.45 530 0.70   700 1.20 775 1.45 840 1.70  2.00  2.25 1005 2.55 - - - - - - - - - - - - - - - - - - - - - - - -
3750 425 0.50 540 0.75  1.05 710 1.30 780  845 1.85  2.15  2.45 1010 2.70  3.00 1110 3.30 - - - - - - - - - - - -
4000 435 0.55 545 0.85  1.10 715 1.40 785 1.70 850 2.00  2.30   1020  1070 3.25 1115 3.55  3.85 1205 4.15 4250 445  555   1.25 725 1.55  1.85 855 2.15  2.45  2.80 1025 3.10 1075 3.45 1120 3.75  4.10 1210 4.45
4500 455 0.70  1.00  1.35 730  800 2.00  2.35    3.00 1030 3.30 1080  1130 4.05 1175 4.35 1215 4.70
4750 470 0.75 575 1.10  1.45 740 1.80 810 2.15 870 2.50  2.85  3.20 1040 3.55 1085  1135 4.25 1180  1225 5.00
5000 480 0.85 585 1.25   750  815 2.30 880 2.70  3.05  3.40 1045 3.80  4.15 1140 4.50 1185  1230 5.30
5250    1.35  1.70 755 2.10 825 2.50    3.25 1000  1050 4.00 1100 4.40 1150 4.80  5.20 1235 
5500 505 1.05  1.45  1.85  2.25 835   3.05  3.45 1010 3.85  4.25 1110 4.70 1155 5.10 1200 5.50 1240 
5750 520 1.15   700 2.00 775 2.45 840 2.85  3.25   1015 4.10  4.50 1115   5.35 1205 5.80 1250 
 530 1.30  1.75 710 2.15 785  850 3.05  3.45   1025 4.35 1075 4.80 1120 5.20 1170  1215  1255 
 545 1.40   720 2.35  2.80  3.25  3.70  4.15 1030  1080 5.05 1130 5.50 1175  1220   
  1.55  2.05 730 2.50 805 3.00 870 3.45    4.40 1040 4.85  5.35 1140 5.85 1185  1225  1270 7.25
 570 1.70  2.20 745 2.70 815 3.20 880 3.70  4.20   1045 5.10   1145    1235 7.10 1275 
7000 585 1.85  2.35 755  825 3.40    4.45 1005  1055 5.40 1105  1155  1200  1240 7.45 1285 8.00 7250  2.00    3.10 835   4.15   1015 5.25  5.75 1115    1205 7.30 1250 7.85  8.35 7500  2.20 700 2.75 775 3.30 845 3.85  4.45   1020 5.50 1075  1125  1170 7.15 1215   8.25 1300 8.75 7750  2.40 715 3.00  3.55 855 4.10  4.70  5.25 1030 5.80 1080  1130  1180 7.50 1225 8.05   1305  8000  2.55 725 3.20 800 3.80  4.35    5.50 1040    1140 7.25 1185 7.85 1230 8.40 1275  1315  8250  2.80 740 3.40 810 4.00 880   5.25  5.85 1050  1100 7.05 1150   8.25 1240 8.85 1280  1325 10.05 8500  3.00 750  825 4.30    5.55 1005    1110 7.40  8.05 1205  1250    1330 10.45 8750  3.25   835 4.55  5.20  5.85 1015  1070 7.15 1120 7.75  8.35 1215  1255  1300 10.30 1340   700 3.50 780 4.20 850 4.85  5.50   1025  1080 7.50 1130 8.15 1175 8.75 1220   10.10 1310 10.80 1350 11.40  715 3.75  4.45  5.15  5.85   1040 7.20  7.85 1140 8.55 1185  1230  1275 10.55 1315 11.20 - - - - - -
 730 4.00 805 4.75 875 5.45     1050  1100 8.25 1150    1240 10.30 1285 11.05 - - - - - - - - - - - -
 745 4.30 820 5.05 885 5.75   1005 7.20   1110    1205 10.05 1250 10.80  11.50 - - - - - - - - - - - -
   835 5.40     1015  1070 8.35 1120  1170  1215 10.50  11.25 - - - - - - - - - - - - - - - - - -
 775  845     7.20 1030 8.00 1080 8.75 1135  1180 10.25 1225 11.00 - - - - - - - - - - - - - - - - - - - - - - - -
  5.20       1040 8.40   1145 10.00  10.70 1235 11.45 - - - - - - - - - - - - - - - - - - - - - - - -
 805 5.55 875   7.25 1000 8.05 1055 8.85 1105  1155 10.45 1200 11.20 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 820      1010 8.45   1115 10.05   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


BLOWER DATA
FACTORY INSTALLED BELT DRIVE KIT SPECIFICATIONS
Nominal
hp
Maximum
hp
Drive Kit Number RPM Range
3 3.45 1 535 - 725
3 3.45 2 
5 5.75 3 
5 5.75 4 850 - 1045
5 5.75 5 
7.5   850 - 1045
7.5  7
7.5  8 1045 - 1285
10 11.50 7 
10 11.50 10 1045 - 1285
10 11.50 11 



NOTE – Motor service factor limit - 1.0
FACTORY INSTALLED OPTIONS/FIELD INSTALLED ACCESSORY AIR RESISTANCE
Air
Volume
cfm
Wet Indoor
Coil
Gas Heat Exchanger
Economizer Filters Horizontal
Roof Curb
Low/
Standard
Heat
Medium
Heat
High
Heat
in. w.g. in. w.g. in. w.g. in. w.g. in. w.g. MERV 8 MERV 13 MERV 16 in. w.g.
2750 .02 .02 .04 .05 - - - .01 .03  .03
3000 .02 .03 .04 .05 - - - .01 .03  .04
3250 .03 .03 .05  - - - .01 .04 .07 .04
3500 .03 .03 .05  - - - .01 .04 .08 .05
3750 .03 .04  .07 - - - .01 .04 .08 .05
4000 .04 .04  .07 - - - .01 .04  
4250 .04 .04  .08 - - - .01 .05 .10 .07
4500 .05 .05 .07  - - - .01 .05 .10 .07
4750 .05 .05 .08 .10 - - - .02 .05 .11 .08
5000 .05 .05  .11 - - - .02  .12 .08
5250   .10 .12 - - - .02  .12 
5500 .07  .10 .13 - - - .02  .13 .10
5750 .07  .11 .14 - - - .02 .07 .14 .11
 .08 .07 .12 .15 - - - .03 .07 .14 .11
 .08 .07 .12  .01 .03 .07 .15 .12
  .08 .13 .17 .02 .03 .08  .13
 .10 .08 .14 .18 .03 .03 .08 .17 .14
7000 .10  .15  .04 .04 .08 .17 .15
7250 .11   .20 .05 .04  .18 
7500 .12 .10 .17 .21  .04   .17
8000 .13 .11  .24  .05 .10 .21 
8500 .15 .12 .20  .11 .05 .10 .22 .21
  .13 .23  .14  .11 .24 .24
 .18 .14 .25 .32  .07 .12 .25 
 .20  .27 .35  .07 .12 .27 
 .22 .17 .30 .38 .22 .08 .13  .31
 .24 .18 .31 .40 .25  .14 .30 .34
BLOWER DATA

Page 10
POWER EXHAUST FAN PERFORMANCE
Return Air System Static Pressure Air Volume Exhausted
in. w.g. cfm
0.00 
0.05 8210
0.10 7725
0.15 7110
0.20 
0.25 
0.30 
0.35 4300
0.40 3510
0.45 
0.50 1840
CEILING DIFFUSER AIR RESISTANCE - in. w.g.
Air
Volume
cfm
󰀨 󰀨
RTD11-185S RTD11-275S
FD11-185S FD11-275S
2 Ends Open 1 Side/2 Ends
Open
All Ends &
Sides Open 2 Ends Open 1 Side/2 Ends Open
All Ends &
Sides Open
5000 .51 .44  - - - - - - - - - .27 - - -
5200  .48 .42 - - - - - - - - - .30 - - -
5400  .52 .45 - - - - - - - - - .33 - - -
   .48 - - - - - - - - -  - - -
5800 .71  .51 - - - - - - - - -  - - -
   .55  .31 .27 .42 
 .80   - - - - - - - - -  - - -
  .72  - - - - - - - - - .50 - - -
 - - - - - - - - - .42  .31 - - - .34
  .77  - - - - - - - - - .54 - - -
  .83 .72 - - - - - - - - - .58 - - -
7000 1.03 .87   .41   .40
7200   .80 - - - - - - - - -  - - -
7400 1.15  .84 - - - - - - - - - .70 - - -
7500 - - - - - - - - - .51  .41 - - - .45
 1.20 1.02 .88 - - - - - - - - - .74 - - -
8000 - - - - - - - - -   .43 - - - .50
8500 - - - - - - - - -  .58 .50 - - - .57
 - - - - - - - - -   .58 - - - 
 - - - - - - - - -  .75  - - - .74
 - - - - - - - - - 1.00 .84 .73 - - - .81
 - - - - - - - - - 1.10  .80 - - - 
 - - - - - - - - - 1.21 1.01 .88 - - - 
CEILING DIFFUSER AIR THROW DATA - ft.
Model
No.
Air Volume
cfm
1󰀨 Model
No.
Air Volume
cfm
1󰀨
RTD11-185S
Step-Down
FD11-185S
Flush
RTD11-275S
Step-Down
FD11-275S
Flush

180
  28 - 37
240
7200 33 - 38 
5800 42 - 51  7400 35 - 40 28 - 37
 44 - 54 40 - 50   
 45 - 55 42 - 51 7800 38 - 43 40 - 50
  43 - 52 8000  42 - 51
   8200  43 - 52
1
󰀨
open.
8400  44 - 54
 44 - 50 
8800 47 - 55 
BLOWER DATA