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Service Literature
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 main
tenance), disable power to blower, remove fan belt
where applicable, and ensure all controllers and ther
mostats are set to the "OFF" position before
performing maintenance.
3-
Always keep hands, hair, clothing, jewelry, tools, etc.,
away from moving part
The LDT commercial combination heat pump and gas heat
unit is available in 6.5 / 7.5 / 8.5 / 10 / 12.5 ton cooling ca
pacities. The LDT078, 092, 102, 122 and 150 refrigerant
systems utilize two compressors, two reversing valves, two
accumulators (122, 150 only), and other parts common to a
heat pump. Units are available in 130,000, 180,000 or
240,000Btuh (38.1, 52.7 or 70.3 kW) heating inputs. Gas
heat sections are designed with stainless steel tube heat
exchangers.
LDT078-150 units are equipped with variable-volume, di
rect drive blowers. These units will provide supply air at
lower speeds when cooling demand is low and increase to
higher speeds when cooling demand is high. Refer to Sup
ply Air Start-Up sections.
LDT units are designed to accept any of several different
energy management thermostat control systems with mini
mum field wiring.
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 super
sede 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 licensed professional HVAC in
staller or equivalent, service agency, or the gas sup
plier
100086
LDT DUAL FUEL SERIES
s.
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon
nect switch(es). Unit may have multiple
power supplies.
Table of Contents
Options / Accessories
Specifications
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High Altitude
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Blower Data
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical Data
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
I Unit Components
II Placement and Installation
III Start Up
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
IV System Service Checks
V Maintenance
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VI Accessories
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VII Wiring Diagrams
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LDT
6.5 / 7.5 / 8.5 /10 / 12.5
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Summary of Contents for Lennox LDT Series
- Page 1 Service Literature 6.5 / 7.5 / 8.5 /10 / 12.5 100086 LDT DUAL FUEL SERIES WARNING To prevent serious injury or death: Lock-out/tag-out before performing maintenance. If system power is required (e.g., smoke detector main tenance), disable power to blower, remove fan belt where applicable, and ensure all controllers and ther...
- Page 2 OPT IONS / A C C ESSORIES Unit Model No Catalog Item Description Number 078 092 102 122 150 COOLING SYSTEM Condensate Drain Trap 22H54 Copper 76W27 Drain Pan Overflow Switch 21Z07 GAS HEATING SYSTEM 54W95 Bottom Gas Piping Kit Combustion Air Intake Extensions 19W51 Gas Heat Input...
- Page 3 OPT IONS / A C C ESSORIES Unit Model No Catalog Item Description Number 078 092 102 122 150 INDOOR AIR QUALITY Air Filters Healthy Climate High Efficiency Air Filters MERV 8 50W61 ® 20 x 25 x 2 in. (Order 4 per unit) MERV 13 52W41 MERV 16...
- Page 4 OPT IONS / A C C ESSORIES Unit Model No Catalog Item Description Number 078 092 102 122 150 ECONOMIZER High Performance Economizer (Approved for California Title 24 Building Standards / AMCA Class 1A Certified) High Performance Economizer 20U80 Downflow or Horizontal - Includes Outdoor Air Hood and Downflow Barometric Relief Dampers with Exhaust Hood Order Horizontal Barometric Relief Dampers separately Horizontal Barometric Relief Dampers...
- Page 5 SP ECIF ICATIONS 6.5 TO N | 7 .5 TO N | 8.5 TO N General Data Nominal Tonnage 6.5 Ton 7.5 Ton 8.5 Ton Efficiency Type High High High Model Number LDT078H4E LDT092H4E LDT102H4E Blower Type DirectPlus™ DirectPlus™ DirectPlus™ ECM Direct Drive ECM Direct Drive ECM Direct Drive...
- Page 6 SP ECIF ICATIONS 10 TO N | 1 2 . 5 TO N General Data Nominal Tonnage 10 Ton 12.5 Ton Efficiency Type High High Model Number LDT122H4E LDT150H4E Blower Type DirectPlus™ DirectPlus™ ECM Direct Drive ECM Direct Drive with MSAV® with MSAV®...
- Page 7 SP ECIF ICATIONS G A S HEAT Heat Input Type Standard Medium High Number of Gas Heat Stages Gas Heating Input - Btuh First Stage 84,500 117,000 156,000 Performance Second Stage 130,000 180,000 240,000 Output - Btuh Second Stage 104,000 144,000 194,000 Temperature Rise Range - °F...
- Page 8 B LOWER D ATA BLOWER TABLE INCLUDES RESISTANCE FOR BASE UNIT ONLY (NO HEAT SECTION) WITH DRY INDOOR COIL AND AIR FILTERS IN PLACE. FOR ALL UNITS ADD: 1 − Wet indoor coil air resistance of selected unit. 2 − Any factory installed options air resistance (heat section, Economizer, etc.) 3 −...
- Page 9 BLO WER DATA FACTORY INSTALLED OPTIONS/FIELD INSTALLED ACCESSORY AIR RESISTANCE - in. w.g. Wet Indoor Coil Gas Heat Exchanger Filters Return Volume Economizer Standard Medium High Adaptor 092, 102 MERV 8 MERV 13 MERV 16 Heat Heat Heat Plate 1750 0.04 0.04 0.06...
- Page 10 BLO WER DATA CEILING DIFFUSERS AIR RESISTANCE - in. w.g. RTD11 Step-Down Diffuser FD11 Flush Air Volume 1 Side, 2 Ends All Ends & Sides Diffuser Unit Size 2 Ends Open Open Open 2400 0.21 0.18 0.15 0.14 2600 0.24 0.21 0.18 0.17...
- Page 11 ELECTRIC AL DATA 6 .5 TO N Model No. LDT078H4E Voltage - 60Hz 208/230V-3ph 460V-3ph 575V-3ph Compressor 1 Rated Load Amps 12.9 (Non-Inverter) Locked Rotor Amps Compressor 2 Rated Load Amps (Non-Inverter) Locked Rotor Amps Outdoor Fan Full Load Amps (2 ECM) Motors (2) Total Power Exhaust...
- Page 12 ELECTRIC AL DATA 8 .5 TO N Model No. LDT102H4E Voltage - 60Hz 208/230V-3ph 460V-3ph 575V-3ph Compressor 1 Rated Load Amps 12.9 (Non-Inverter) Locked Rotor Amps Compressor 2 Rated Load Amps (Non-Inverter) Locked Rotor Amps 38.9 Outdoor Fan Full Load Amps (2 ECM) Motors (2) Total Power Exhaust...
- Page 13 LDT078-150 PARTS ARRANGEMENT INDOOR BLOWER OUTDOOR FANS COIL (DIRECT DRIVE) (3 ON 122 & 150) FILTERS (FOUR - 20 X 25 X 2”) ECONOMIZER (OPTIONAL) WIFI ANTENNA UNIT CONTROLLER COMBUSTION WIRELESS AIR INDUCER BOARD GAS VALVE COMPRESSORS BURNERS CONDENSATE REVERSING DRAIN VALVE FIGURE 1...
- Page 14 (A6), after the economizer 2-Transformer T1 dampers reach 50% open (adjustable on control A6). All LDT series units use a single line voltage to 24VAC When K65 closes, the exhaust fan B10 is energized. transformer mounted in the control box. Transformer sup...
- Page 15 PLUMBING COMPONENTS LDT078-102 Condenser Coil Evaporator Coil Reversing Valve Reversing Valve Compressor 2 Compressor 1 LDT122-150 Condenser Coil Evaporator Coil Reversing Valve Accumulators Compressor 1 Compressor 2 FIGURE 4 Page 15...
- Page 16 B-Cooling Components 2-Freezestats S49 and S50 Each unit is equipped with a low temperature switch LDT units use independent cooling circuits consisting of (freezestat) located on the return bend of each indoor coil. S49 (first circuit) and S50 (second circuit) are located on separate compressors, outdoor coils and indoor coil (with 2 the corresponding indoor coils.
- Page 17 5-Reversing Valve L1 and L2 8-Filter Drier (all units) LDT units have a filter drier located in the liquid line of each A refrigerant reversing valve with a 24 volt solenoid coil is refrigerant circuit at the exit of each condenser coil (outdoor used to reverse refrigerant flow during unit operation in all coil in LDT units).
- Page 18 LDT078, 092, 102, 122, 150 INDOOR COIL RT46, RT47 22J06 BLUE RT47 22J06 YELLOW RT46 DETAILS NOT TO SCALE FIGURE 5 Page 18...
- Page 19 LDT078, 092, 102, 122, 150 OUTDOOR COIL RT48, RT49 22J08 BLUE RT49 22J08 YELLOW RT48 DETAILS NOT TO SCALE FIGURE 6 Page 19...
- Page 20 C-Blower Compartment NOTE - Blower operation mode can also be initiated by the mobile service app. The blower compartment in all LDT078-150H units is locat Direct-drive motor may not immediately stop when power is ed between the indoor coil and the outdoor coil section. The interrupted to the Unit Controller.
- Page 21 LOCATION OF STATIC PRESSURE READINGS INSTALLATIONS WITH DUCTWORK INSTALLATIONS WITH CEILING DIFFUSERS ROOFTOP UNIT ROOFTOP UNIT RETURN AIR READING LOCATION RETURN AIR READING RE RE LOCATION SUPPLY SUPPLY TURN TURN FIRST BRANCH OFF OF MAIN RUN MAIN DUCT RUN SUPPLY AIR SUPPLY AIR READING READING...
- Page 22 TABLE 1 DIRECT DRIVE PARAMETER SETTINGS - 581102-01 Field Parameter Description Setting Note: Any changes to Smoke CFM setting must be adjusted before the other CFM settings. Use SETTINGS > RTU OP TIONS > EDIT PARAMETERS = 12 for EBM, 6 for ECM BLOWER SMOKE CFM % Percentage of RPM for blower smoke speed.
- Page 23 D-Gas Heat Components 2-Gas Heat Exchanger Inserts (Figure 10) Units are available in 130,000 BTUH, 180,000 BTUH or Inserts are installed on standard (130,000Btuh) heat ex 240,000 BTUH heat sizes. changers. Medium and high heat exchangers do not re quire inserts. 1-Heat Exchanger Figure 9 Inserts are used to maintain even temperature distribution HEAT EXCHANGER ASSEMBLY...
- Page 24 Limit S47 is factory preset to open at 290_F + 12_F (143_C Orifice Each burner uses an orifice which is matched to the + 6.7_C) on a temperature rise on all units. All flame roll-out burner input. The orifice is threaded into the burner limits are manual reset.
- Page 25 9-Gas Valves GV1 Spark gap may be checked with appropriately sized twist drills or feeler gauges. Disconnect power to the unit and re move electrode assembly. The gap should be between Gas valve GV1 is a two‐stage redundant valve.. On first 0.125”...
- Page 26 12-Burner Control A3 TABLE 4 UTEC WARNING Indicates Flashes Shock hazard. Spark related compo Slow Flash Control ok, no call for heat nents contain high voltage which can cause personal injury or death. Discon Fast Flash Control ok, call for heat present. nect power before servicing.
- Page 27 IGNITION CONTROL TIMING É É É END OF 6 (+3.4, -2.0) SEC. THERMOSTAT É É É DEMAND SECONDS 0 HEATING CYCLE THERMOSTAT DEMAND É É É É É É É É É É É É É É COMBUSTION AIR BLOWER É...
- Page 28 II-PLACEMENT AND INSTALLATION C-Gas Heating Start Up FOR YOUR SAFETY READ BEFORE LIGHTING Make sure the unit is installed in accordance with the instal lation instructions and all applicable codes. See acces sories section for conditions requiring use of the optional WARNING roof mounting frame (LARMF).
- Page 29 Placing Unit In Operation 1- Set HP balance point thermostat setpoint above the outdoor ambient temperature to disable heat pump op eration. WARNING WHITE RODGERS 36H54 GAS VALVE Danger of explosion and fire. Can cause Two-Stage injury or product or property damage. You must follow these instructions exactly.
- Page 30 E-Cooling Start Up REFRIGERANT STAGES - 078, 092, 102 IMPORTANT (BOTH FANS ARE ENERGIZED IN LOW SPEED WITH A Y1 DEMAND AND HIGH SPEED WITH A Y2 DEMAND) If unit is equipped with a crankcase heater. Make sure heater is energized 24 hours before unit start-up to OUTDOOR COIL OUTDOOR prevent compressor damage as a result of slugging.
- Page 31 IV- SYSTEMS SERVICE CHECKS TABLE 5 581118-01 LDT078 CIRCUIT 1 CIRCUIT 2 WARNING Outdoor Dis Dis Coil charge Suction charge Suction Entering Refrigerant can be harmful if it is inhaled. Refrigerant +5 psig +5 psig +10 psig +10 psig Air Temp must be used and recovered responsibly.
- Page 32 TABLE 9 581122-01 GAS PIPING COMPONENTS LDT150 REFER TO INSTALLATION INSTRUCTIONS CIRCUIT 1 CIRCUIT 2 Outdoor VALVE Dis Dis Coil GROUND JOINT UNION Suction Suction charge charge Entering +10 psig +5 psig +10 psig +5 psig Air Temp 65 °F MANUAL MAIN 75 °F SHUT-OFF VALVE...
- Page 33 4-Check and Adjust Manifold Pressure 6-Heat Exchanger To Access or Remove Heat Exchanger From Unit: After line pressure has been checked and adjusted, check manifold pressure. Move test gauge to the outlet pressure 1- Turn off gas and electric power. tap located on unit gas valve GV1.
- Page 34 V-MAINTENANCE D-Indoor Coil Inspect and clean coil at beginning of each cooling and The unit should be inspected once a year by a qualified ser heating season. Clean using mild detergent or commercial vice technician. coil cleanser. Flush coil and condensate drain with water CAUTION taking care not to get insulation, filters and return air ducts wet.
- Page 35 VI-ACCESSORIES TYPICAL FLASHING DETAIL The accessories section describes the application of most UNIT BASE of the optional accessories which can be factory or field in BOTTOM stalled to the LDT units. OPTIONAL ACCESSORIES sec tion (see table of contents) show specific size per unit. UNIT BASE RAIL A-C1CURB Mounting Frames FIBERGLASS...
- Page 36 C1DAMP20B-1 MOTORIZED OUTDOOR AIR DAMPER MOTORIZED DAMPER COVER PANEL HORIZONTAL SUPPLY AIR OPENING COMPRESSOR HORIZONTAL SECTION RETURN AIR OPENING LOWER PANEL C1DAMP10B-1 MANUAL OUTDOOR AIR DAMPER COVER PANEL MANUAL DAMPER HORIZONTAL SUPPLY AIR OPENING COMPRESSOR HORIZONTAL SECTION RETURN AIR OPENING LOWER PANEL FIGURE 25 Page 36...
- Page 37 ECONOMIZER ACCESSORY PANEL MULLION ECONOMIZER DIVIDER PANEL BOTTOM OF COMPRESSOR SECTION FLANGED RETURN AIR OPENING FIGURE 26 E-K1ECON20B Economizer Temperature offset is the default free cooling mode. NOTE - All free cooling modes of operation will modu (Field- or Factory-Installed) late dampers to 55_F (13_C) supply / discharge air.
- Page 38 The dampers must be used any time an economizer and a power exhaust fan is applied to LDT series units. Barometric relief dampers allow exhaust air to be dis charged from the system when an economizer and/or pow...
- Page 39 A6 ENTHALPY CONTROLLER POWER EXHAUST FAN AND BAROMETRIC EXHAUST DAMPER INSTALLATION ADJUST POWER EXHAUST FAN SETPOINT GED GRAVITY EXHAUST ENERGIZED WHEN DAMPERS DAMPER POSITION Open IS HIGHER THAN EXHAUST FAN SETPOINT PEF POWER EXHAUST FAN ASSEMBLY (ORDERED SEPARATELY) FIGURE 29 Power Exhaust Setpoint Adjustment Free Cool...
- Page 40 VII- WIRING DIAGRAMS / SEQUENCE OF OPERATION GAS HEAT FOR LDT 078H-150H Y and G Voltage MODBUS A55.P393 MAIN CTRL 1 3 2 J413 J393 P413 P393 LOW TEMP VEST HTR BURNER 1 LTVH−1 MODBUS P229 CABLE FROM LTVH−2 P411 P406 P229 J411...
- Page 41 GAS HEAT FOR LDT078H-150H J Voltage MODBUS A55.P393 MAIN CTRL J413 J393 P413 P393 LOW TEMP VEST HTR BURNER 1 LTVH−1 MODBUS P229 CABLE FROM LTVH−2 P411 P406 J411 J406 A G B DSI CTRL 1 MODBUS−1 J407 J410 P407 P410 DRNWR MODBUS CABLE...
- Page 42 GAS HEAT SEQUENCE OF OPERATION LDT078H-150H First Stage Heat: End of Second Stage Heat: 1- Heating demand initiates at W1 in the thermostat. 8- Heating demand is satisfied. Terminal W2 (high fire) is 2- 24VAC is routed through the A55 unit controller to A3 de-energized.
- Page 43 ELECTRONIC OR ELECTROMECHANICAL THERMOSTAT − 0 1 A173 CTRL SMOKE DETECT J250 P250 P251 J251 J252 P252 P253 J253 FIRE ALARM CONTACT SUPPLIED BY OTHERS FROM IAQ WIRING DIAGRAM DI−1 P299 P387 J299 J387 MAIN CTRL J297 J298 P297 P298 J387 J298 J297 J299 IAQ+...
- Page 44 LDT SERIES ECONOMIZER MS7110K RANGE 2−10 VDC NF24−SR AF24−SR RANGE 2−10 VDC P104 P105 RT16 J104 J105 P384 J384 MAIN CTRL Model: LC, LG, LH, LD Series RTU ACCS ACCS Economizer & Motorized OAD WI R I N G DI A GRAM F LOW...
- Page 45 LDT078/150 Y Voltage With Higher SCCR DRNWR TO A3 ON GAS UNITS. REF A−SECT LOC CC01−02 RED−BLK RED−BLK 24VAC RT17 SHIELDED CABLE HPSW1 TWISTED PAIR HTSW1 DRNWR RED−BLK RED−BLK 24VAC ODF1 RT48 RT46 PWM2 P336 HTSW2 P337 RED−BLK RED−BLK 24VAC RT49 RT47 OPTIONAL IONIZER...
- Page 46 LDT078-150 G Voltage With Higher SCCR DRNWR TO A3 ON GAS UNITS. REF A−SECT LOC CC01−02 RED−BLK RED−BLK 24VAC RT17 SHIELDED CABLE HPSW1 TWISTED PAIR HTSW1 DRNWR RED−BLK RED−BLK 24VAC ODF1 RT48 RT46 PWM2 P336 HTSW2 P337 RED−BLK 24VAC RED−BLK RT49 RT47 OPTIONAL IONIZER...
- Page 47 LDT078-150 J Voltage With Higher SCCR DRNWR TO A3 ON GAS UNITS. REF A−SECT LOC CC01−02 RED−BLK RED−BLK 24VAC RT17 SHIELDED CABLE HPSW1 TWISTED PAIR HTSW1 DRNWR RED−BLK RED−BLK 24VAC ODF1 RT48 RT46 PWM2 P337 HTSW2 P336 RED−BLK RED−BLK 24VAC RT49 RT47 OPTIONAL IONIZER...
- Page 48 SEQUENCE OF OPERATION LDT078-150 Power: 1. Line voltage through the S48 unit disconnect, TB2 terminal block, or CB10 circuit breaker energizes the T1 transformer. T1 provides 24VAC power to A55 Unit Controller which provides 24VAC to the unit cooling, heating and blower controls. 2.
- Page 49 SEQUENCE OF OPERATION LDT078-150 (continued) First Stage Heat - OD Temp BELOW Balance Point (35°F Default) Outdoor Ambient Temperature W1 Demand W2 Demand 5. Unit controller A55 receives W1 demand. If the OD air temperature is BE Above Balance Point Tempera Compr.
- Page 50 DIRECT DRIVE BLOWER SEQUENCE OF OPERATION / TROUBLESHOOTING Blower Operation: Line voltage is routed to B3 blower motor through TB2 terminal strip, TB13 terminal strip and J/P48 terminals 1, 2 and 3. B3 blower motor runs internal diagnostics to check for proper temperature, voltage, etc. (KL2-2 and -3). This process takes approximately 10 seconds.
- Page 51 TABLE 13 DIRECT DRIVE BLOWER MOTOR TROUBLESHOOTING Failure Error Warning Reason Troubleshoot Check for obstruction keeping Locked Rotor • No changes in hall signals within 2000ms impeller from rotating Check for secondary airflow source in the system causing Warning, no error code set, Motor start not pos Braking Mode •...
- Page 52 DIRECT DRIVE BLOWER SEQUENCE OF OPERATION / TROUBLESHOOTING Blower Operation: Line voltage is routed to B3 blower motor through TB2 terminal strip, TB13 terminal strip and J/P48 terminals 1, 2 and 3. B3 blower motor runs internal diagnostics to check for proper temperature, voltage, etc. (KL2-2 and -3). This process takes approximately 10 seconds.
- Page 53 TABLE 14 DIRECT DRIVE BLOWER MOTOR TROUBLESHOOTING Failure Error Warning Reason Troubleshoot Check for obstruction keeping Locked Rotor • No changes in hall signals within 2000ms impeller from rotating Check for secondary airflow source in the system causing Warning, no error code set, Motor start not pos Braking Mode •...