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INSTALLATION

INSTRUCTION 

VRF SYSTEMS -- Indoor Units

507893-03

09/2019

Shipping and Packing List 

General

The VMDB medium-static ducted indoor units are matched 

with an outdoor heat recovery or heat pump unit to create 

a VRF (variable refrigerant flow) system that uses R-410A 

refrigerant. VMDB indoor units are designed for indoor 

installation only. 

Refer to the Product Specification bulletin (EHB) for the 

proper use of these indoor units with specific heat pumps, 

heat  recovery  units,  mode  switching  devices,  branch 

pipes, line sets and controls.

These instructions are intended as a general guide and 

do not supersede local or national codes in any way. 

Authorities having jurisdiction should be consulted before 

installation.

VMDB Medium-Static Units

Check the components for shipping damage. If you find 

any damage, immediately contact the last carrier.

Package 1 of 1 contains the following:

1 - Assembled medium static, ducted unit

2 - Condensate drain insulation sleeves
1 - Flexible condensate connector

1 - Hose clamp
2 - Pipe reducers (VMD007, 009, 012 & 015)

1 - Resistor
1 - Cable
1 - Installation manual

THIS MANUAL MUST BE LEFT WITH THE OWNER 

FOR FUTURE REFERENCE

These instructions are intended as a general guide and do 

not supersede local codes in any way. Consult authorities 

having jurisdiction before installation.

 WARNING

Improper installation, adjustment, alteration, ser vice or 

maintenance  can  cause  property  damage,  personal 

injury or loss of life.

Installation and service must be performed by a li censed 

professional HVAC installer, service agency or the gas 

supplier.

Failure to follow safety warnings and these instruc tions 

exactly  could  result  in  property  damage,  dan gerous 

operation, serious injury, or death.

Any additions, changes, or conversions required in order 

for the appliance to satisfactorily meet the ap plication 

needs must be made by a licensed profes sional HVAC 

installer (or equivalent) using factory-specified parts.

Do not use this system if any part has been under water. 

A  flood-damaged  appliance  is  extremely  dan gerous. 

Immediately call a licensed professional HVAC service 

technician (or equivalent) to inspect the system and to 

replace all controls and electrical parts that have been 

wet, or to replace the system, if deemed necessary.

 IMPORTANT

The Clean Air Act of 1990 bans the intentional venting 

of refrigerant (CFCs, HCFCs and HFCs) as of July 1, 

1992.  Approved  methods  of  recovery,  recycling  or 

reclaiming must be followed. Fines and/or incarceration 

may be levied for noncompliance. These units must be 

installed as a part of a matched system as specified in 

the Product Specifications (EHB) bulletin.

 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.

To  ensure  proper  system  performance  and  reliability, 

Lennox does not recommend operation of VRF systems 

during any phase of construction. Construction debris, 

low temperatures, harmful vapors, and operation of the 

unit with misplaced filters can damage the units. Failure 

to follow these guidelines will result in the warranty 

being voided.

VRF

©2019 Lennox Industries Inc. Dallas, Texas, USA

Summary of Contents for VRF VMDB Series

Page 1: ...sed professional HVAC installer service agency or the gas supplier Failure to follow safety warnings and these instruc tions exactly could result in property damage dan gerous operation serious injury...

Page 2: ...ce a fuse with a fuse of a different rating Do not use a jumper wire to replace a fuse Do not insert your hands tools or any other item into the air intake or air outlet at either the indoor or outdoo...

Page 3: ...UNIT REAR OF UNIT SECTION A A SECTION D D SECTION B B SECTION C C SECTION B B SECTION C C SECTION A A SECTION D D TOP OF UNIT NOTE Unit orientation reversed to show alternative filter location and re...

Page 4: ...2 13 1 25 1 3 4 44 1 7 8 48 CONDENSATE LIFT PUMP Size A B C D E F G H J in mm in mm in mm in mm in mm in mm in mm in mm in mm 012 36 1 4 921 10 5 8 270 25 3 8 645 22 1 2 572 39 3 4 1010 2 5 8 67 28 71...

Page 5: ...in any form Minimum clearances must be observed at all times NOTE Horizontal installation only 20 508 mm Minimum Service Clearance 24 610 mm Air Flow 24 610 mm Minimum Service Clearance TOP VIEW DUCT...

Page 6: ...te support for the weight of the duct system Duct system must not be supported by the indoor unit It is recommended that you use flexible joints canvas at the point where the duct connects to the unit...

Page 7: ...d then a nut onto each rod below each suspension bracket Use the leveling nut beneath suspension bracket to adjust the unit to the correct height Remove the electrical tape holding the upper washers a...

Page 8: ...es the filter retaining bracket and slide the bracket away from the unit 3 Grasp the filter removal tab and slide the filter out Figure 7 Loosen Filter Retaining Bracket Filter removal tab Figure 8 Sl...

Page 9: ...pplied foam insulating tape to the return air opening on the bottom of the unit See Figure 11 Figure 11 Apply Foam Insulating Tape Field supplied foam insulating tape 5 Use the existing screws to re i...

Page 10: ...PORTANT Support ALL piping within 12 in 305 mm of any mechanical fitting such as a flared connection WARNING Danger of fire Bleeding the refrigerant charge from only the high side may result in pressu...

Page 11: ...on conditions 4 All refrigerant piping shall be free of defects debris and oil 5 Connect the liquid and gas lines to the evaporator coil 6 Always use an appropriate heat absorption compound to protect...

Page 12: ...rnal drain pump Suspension Rods Drain line Structural Ceiling 3 ft 1 m Support straps NOTE Drain line should be sloped 1 4 inch per foot 18 mm per m AWAY from unit and should be supported as needed to...

Page 13: ...system in the cooling mode If the internal pump is being used ensure that the pump is operating and the water in the pan is draining freely If the internal pump is not being used pour the water into t...

Page 14: ...ions Clamp cables securely and make sure that connections are tight to avoid strain on wiring Insecure wiring connections may result in equipment failure and risk of fire Wiring must be installed so t...

Page 15: ...gure 21 Typical Power Wiring Diagram VRF Heat Recovery System Shown L2 L3 L1 L2 L1 208 230V 3Ph 60Hz or 460V 3Ph 60Hz Power supply 208 230V 1Ph 60Hz Power supply Mode Selection Box Indoor unit Indoor...

Page 16: ...PQ PQ H1 H2 H1 H2 H1 H2 Outdoor Unit Communication Terminal Block P Q H1 H2 X Y O A K1 K2 MS Box Communication Terminal Block P Q Indoor Unit Communication Terminal Block HA HB 12V COM P Q Ground drai...

Page 17: ...ler Signal transmission wire X2M 0 58 0 72 Terminal base of power supply X1M 0 87 1 06 Grounding terminal M4 1 06 1 43 PQ PQ Outdoor unit mainunit Outdoor unit sub1unit Outdoor unit sub2 unit Install...

Page 18: ...E F8 No address Outdoor unit fault Water level alarm Emergency stop Remote OFF E6 DC fan motor error E7 EEPROM failure error 5V GND 12V ONLY USED FOR TESTING CN30 RED BLACK HA HB 12V COM Q P Magnet Ri...

Page 19: ...6 Locate the return air thermistor to the conditioned area of which the indoor unit serves Figure 29 Sensor Thermistor Relocate the unit return air sensing from inside the unit to a location within th...

Page 20: ...K WHITE RED XS4 XS3 XS2 XS1 XS6 XP7 XS7 CN12 NOTE 1 Refer to manual for communication wiring 2 Please use the 2 conductor shielded twisted cable for communication NOTE Component in dash line is option...

Page 21: ...l indoor temperature T1 6 The middle coil temperature T2 7 The coil inlet temperature T2A 8 The coil outlet temperature T2B 9 The actual superheat temperature 10 The actual subcool temperature 11 Erro...

Page 22: ...it Fault EE High Water Alarm A0 Emergency stop D8 Remote off U4 MS self inspection error F8 MS error Table 8 Fault Code Display on Controller Error Code Description F0 Communication Address error betw...

Page 23: ...23...

Page 24: ...m Reference and adhere to the latest revision of the installation instructions Installation instructions can be downloaded from www lennoxvrf com www lennoxcommercial com www lennoxpros com and the Le...

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