YMGI WMMS-12EC-V2B592 Manual

YMGI: Engineered Comfort Products for An Efficient
and Sustainable Green World!
INSTALLATION INSTRUCTIONS & USER'S MANUAL
DC INVERTER MULTIPLE ZONE (59)2 EC
SYMPHONY CHOIR CEILING CASSETTE INDOOR UNIT
For Model Numbers:
WMMS-12EC-V2B(59)2
WMMS -18EC-V2B(59)2
WMMS -24EC-V2B(59)2
Thank you for choosing this YMGI product. Please read the user’s manual carefully before installation/operation and retain for your records
and future reference. If you need a replacement copy, please contact your local agent or visit www.ymgigroup.com to download a current
electronic version.
NOTICE
This product is designed and manufactured to be free from any defects in material and workmanship during normal use and
maintenance. Installation, operation, maintenance and repair must follow all standards and professional practices for regular cooling
and heating equipment, such as NEC, State, or Local Codes and all related documents/manuals provided by YMGI. Failure to follow
and adhere to all codes and documentation can cause damage to equipment, property even personal injury.
Installer: Currently licensed/certified HVAC technicians only. Must Read the manual and all provided documents prior to installation.
Complete and fill out all required information on the warranty registration card.
User: Retain this manual and all supplied documents for your records and future reference.
Servicer: Use this manual for information concerning servicing and maintenance of this product.
SAFETY WARNING
Only qualified technicians should install and service this equipment. The installation, startup, operation and servicing of this equipment
can be hazardous and requires a HVAC professional who has been trained, licensed and certified. Installations, adjustments or any
equipment alterations done by an unqualified person could result in serious injury and even death. When working on the equipment,
observe all precautions in the provided documents, on the tags, stickers, and labels that are attached to or placed on the equipment.

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Table of Contents
Introduction .................................................................................................................................................. 3
Important Environmental Concerns ............................................................................................................... 3
Responsible Refrigerant Practices ................................................................................................................. 3
Disposal Notice .............................................................................................................................................. 3
Proper Field Wiring ........................................................................................................................................ 3
Personal Protective Equipment ...................................................................................................................... 3
Copyright ........................................................................................................................................................ 4
Basic Cautions and Warnings ........................................................................................................................ 4
Note From YMGI ............................................................................................................................................ 5
Installing Technician/Contractor’s Responsibilities ........................................................................................ 7
Limited Product Warranty ............................................................................................................................... 8
Why Require Professional Installation ........................................................................................................... 11
Suggestions on Hiring a HVAC Professional ................................................................................................. 11
Safety Precautions ......................................................................................................................................... 12
Brief Introduction to Ceiling Cassette Mini Split System ................................................................................ 13
Indoor Unit Diagram ....................................................................................................................................... 14
Specifications ................................................................................................................................................. 15
Unit Dimensions.............................................................................................................................................. 16
Wiring Connections ........................................................................................................................................ 17
Recommended Tools ..................................................................................................................................... 18
Installation Instructions ................................................................................................................................... 19
Installation Accessories .................................................................................................................................. 20
Installation Clearance ..................................................................................................................................... 21
Hanging Preparation ...................................................................................................................................... 22
Installation of Drainage Pipe .......................................................................................................................... 22
Connecting Refrigerant Pipes ........................................................................................................................ 25
Electrical Wiring ............................................................................................................................................. 26
Test and Check Items after Installation .......................................................................................................... 27
Safety Precautions ......................................................................................................................................... 28
Connect Refrigeration Pipes between Indoor Unit and Outdoor Unit ............................................................ 29
Vacuum Testing and Charging ....................................................................................................................... 31
Remote Controller .......................................................................................................................................... 32
Remote Functions .......................................................................................................................................... 33
Cleaning and Care ......................................................................................................................................... 39
Cleaning Air Filters ......................................................................................................................................... 39
Cleaning Air Intake ........................................................................................................................................ 40
Troubleshooting ............................................................................................................................................. 41
Error Codes for the Indoor Unit ...................................................................................................................... 43
Installation, Maintenance and Service Notes ................................................................................................. 47

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Introduction
Read this manual carefully, making sure you understand all the instructions, practices and procedures contained in this manual. Be sure
you are familiar with all the safety advisories that appear throughout this manual. Your personal safety depends upon your observance
of all precautions contained in this manual.
The 3 types of advisories are defined in the following table:
Indicates a potentially hazardous situation which, if not avoided, could result in serious
injury or even death.
Indicates a potentially hazardous situation which, if not avoided, could result in minor or
moderate injury. It is also used to alert against unsafe practices.
Indicates a situation that could result in equipment or property-damage only. It can also
be used to call attention to important details within this manual.
Important Environmental Concerns
Studies have shown that certain man-made chemicals can affect the earth’s stratospheric ozone layer when released into the atmosphere.
Refrigerants that contain Chlorine, Fluorine and Carbon (CFCs) and those containing Hydrogen, Chlorine, Fluorine and Carbon (HCFCs),
may affect the ozone layer. Not all refrigerants have the same potential impact on the environment. YMGI Group advocates for the
responsible handling of all refrigerants including industry replacements for CFCs such as HCFCs and HFCs.
Responsible Refrigerant Practices
YMGI Group believes that responsible refrigerant practices are important to our customers, the HVAC/R industry and the environment.
All HVAC/R technicians who handle refrigerants must be certified. The Federal Clean Air Act (Section 608) sets forth the requirements
for handling, reclaiming, recovering and recycling of certain refrigerants, the equipment and tools necessary to perform these service
procedures. In addition, some states or municipalities may have additional requirements that must also be adhered to for responsible
management of refrigerants. HVAC/R technicians must know the applicable laws and follow them.
Disposal Notice
Do not dispose of this product or its components as unsorted municipal waste, as they contain items that may require special treatment.
Contact your local waste management company for details.
Proper Field Wiring and Grounding Required!
Failure to follow established electrical codes can result in death, serious personal injury and property damage. All field wiring MUST be
performed by qualified personnel, such as a currently licensed electrician. Improperly installed and grounded field wiring poses FIRE and
ELECTROCUTION hazards. To avoid these hazards, you MUST follow the requirements for field wiring installation and grounding as
described in this manual, by NEC and your state/local electrical codes.
Personal Protective Equipment (PPE) Required!
Failure to wear proper PPE for the job being undertaken could result in serious injury or even death. Technicians must take the necessary
precautions to protect themselves from potential electrical, mechanical, and chemical hazards and MUST follow all precautions in this
manual and on the tags, stickers, and labels, as well as the instructions below:
•Before installing or servicing this unit, technicians MUST put on all PPE recommended for the work being undertaken. ALWAYS
refer to appropriate Material Safety Data Sheets (MSDS) and Occupational Safety and Health Administration (OSHA) guidelines
for proper PPE.
•When working with or around hazardous chemicals, ALWAYS refer to the appropriate MSDS sheets and OSHA guidelines for
information on allowable personal exposure levels, proper respiratory protection, and handling recommendations.
If there is a risk of arc or flash, technicians MUST put on all PPE in accordance with NFPA 70E or other country-specific requirements for
arc flash protection, PRIOR to servicing the unit.

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Copyright
This document and the information contained therein are the sole property of YMGI Group and shall not be used or
reproduced in whole or in part, without the written permission of YMGI Group.YMGI Group reserves the right to revise
thismanualat any time andtomakechangesto its contentwithoutobligationtonotifyanyoneabout anymodifications,
revisions or changes.
•Instructions for installation and use of this product are provided by the manufacturer.
•Installation must be performed by authorized and licensed personnel only and in accordance with all the
requirements of this manual, the NEC, CEC and any state/local codes.
•For safe operation of this unit, please read and follow all instructions carefully.
•The total operation capacity of the indoor units should not exceed 120% of the total capacity of the outdoor units
if all indoor units must operate at their peak capacities all the time. Otherwise, the heating and cooling operation
will be diminished and less efficient which could damage the units.
•Any person responsible for system operation or system maintenance should retain this manual for reference.
•If the unit fails to operate normally, please contact your authorized system installer or HVAC professional as soon
as possible and provide the following information:
Data on the unit (model number, serial number and owner’s name).
A detailed description of the unit’s problem before and after the problem occurred.
•To avoid personal injury or property damage, do not disassemble the unit yourself. If disassembly is required to
check the unit, contact your authorized system installer or HVAC professional as they have the experience and
training necessary to perform this task.
Note: Each unit has been thoroughly tested to ensure it operates correctly before leaving the factory.
Basic Cautions and Warnings
All units shall be installed by an experienced HVAC licensed contractor or technician. Read all manuals before
installation, startup and operation.
All NEC, state, local codes and installation instructions must be followed for all units, otherwise, the unit warranty will
be void and could result in serious damage to people or property.
YMGI Group is not responsible for any damage or loss due to Do-It-Yourself (DIY), self-installation or any improper
installation, operation, service or natural disasters of any kind.
Do not connect powerto the unit until all wiring, tubing and all unit inspections and tests have been completed. Ground
the unit according to the instructions and adhering to NEC, state and local codes.
All wiring connections must be correct and secure. Loose wire(s) or improper contacts may cause arcs or overheating
which can result in a fire hazard.

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Note From YMGI –Must Read
Dear Customers, Installers, and Contractors
Thank you for choosing an YMGI product.
All YMGI's products are fully tested and have passed rigorous safety, performance and manufacturing standards before
being packed and shipped. YMGI only uses suppliers that meet our strict standards for high quality and performance for
all parts. YMGI also recognizes a quality installation is equally important therefore your system must be installed by a
licensed HVAC professional. A quality installation ensures your unit will operate at its highest efficiency and peak
performance for many years of worry free comfort; while a poor installation can result in unit failure and cause the unit to
operate inefficiently, either immediately or over time, resulting in costly repairs.
Because a quality installation is so critical, YMGI provides detailed information in our manuals which will aid the installing
technician and the owner of the unit(s).
At YMGI our goal is to ensure that your YMGI units are installed properly and correctly from the beginning.
The YMGI equipment you purchased is either a split-type or a self-contained cooling/heating system. These types of
systems require a certified and licensed HVAC professional technician for proper installation. Only a certified and licensed
HVAC professional technician will have the knowledge, experience, and attention for all required details to perform a
complete and successful installation. This equipment is different from a window or portable type air conditioners you can
purchase from local big box and retail stores which the manufacturer may not require certified and licensed personnel to
install.
Reading and following YMGI Group recommendations and requirements contained in the following pages and other
documents, is the first step to help ensure a smooth installation and proper operation of your unit for many years.
YMGI does not recommend nor allow any Do-It-Yourself (DIY) installation (partially or fully). Due to the complexity of the
installation of this product most DIY installations usually have problems, either immediate or in the near future. These
problems can cost more to fix than any upfront savings. YMGI warranty does not cover any DIY units.
If you have any questions about your unit or if the unit has a problem, you should first check the manual. If you can’t find a
solution, then contact your local installer or service technician to schedule a service appointment. The technician can
physically inspect the unit. If at the time of inspection, the installer or service technician has any questions about the unit,
they can contact YMGI technical support division directly at:
Toll Free Number: [phone] or Email: techs[email protected]om
IMPORTANT:
YMGI Group is the MEDIA AUTHORITY:
YMGI Group, located in O'Fallon, MO 63366 is the author of all media produced for its products and is the only party able
to give any additional explanation for any data, definitions and or descriptions found within any of its media, including but
not limited to YMGI product brochures, manuals, pamphlets, catalogs, and videos. YMGI's distributors, installers, dealers,
agents, customers or any other third parties will not supersede YMGI in anyway concerning YMGI published materials and
their meaning. Any concerns or questions arising from YMGI distributors, installers, dealers, agents, customers or any other
third parties, should be presented directly to YMGI. YMGI will respond to any concerns or questions, if necessary, about
any of its media in writing.

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Be sure to only hire a certified and currently licensed HVAC Company to complete 100% of the installation so that all
details of the installation are performed correctly and completely.
Factory Warranty will be void if any portion of the installation is not performed by a licensed HVAC contractor/technician.
DIY or partial DIY will also void ALL factory warranties.
Hiring an HVAC technician that is offering their services as a "side job" rather than a licensed HVAC company may
pose possible risk. This may result in an incomplete or unsatisfactory installation, no guarantee for workmanship,
maintenance or further service to your unit.
Have the installation technician read in full the installation manual and all supplied documents for the product model
you purchased. Details within the provided documentation contributes greatly to the success and quality of the
installation. Experience with other manufacturers may not be applied fully to another manufacturer, although there will
be similarities there will also be differences. Ignoring the provided installation procedures is an act of negligence and
may cause unit failure or damage which could be permanent.
It is possible for a licensed contractor/technician to make a mistake during the installation. YMGI does not supervise
nor is able to control the contractor/technician’s installation. It is critical that the installer take each variable into account
during the initial installation. This will ensure a complete and professional installation and that all units work properly.
The following will damage the unit and its key components resulting in loss of factory warranty:
1. Any foreign substances introduced into the system because of failure to seal the ends of the refrigeration piping before
pulling the piping through any structures at time of installation.
2. Not installing an oil P-trap in the copper suction line where the indoor unit is located 18 feet or more below the outdoor
unit.
3. Cross piping and/or cross wiring of any units including more than one single zone or a multi zone system.
4. Not conducting a positive leak check prior to the negative leak check.
5. Not conducting a positive leak check by charging the system with dry-nitrogen 350 PSI to hold for 3+ hours, and
performing soap bubble testing.
6. Not conducting a negative leak check by evacuating the copper lines for 30 minutes for each zone. Vacuum must be
held at 500 microns or better for at least 60 minutes, starting 60-minute timer after the vacuum pump is turned off.
7. Not selecting the correct size of wire or circuit breaker.
8. Not answering ALL questions in the technician's checklist located inside the warranty registration form.
The following may be overlooked, ignored, or considered unimportant during your installer's installation, but will
cause your unit to underperform and may cause unit failure.
1. Any kinks in or improper bending of the copper piping.
2. Any poorly formed flares, not centering the flare with the flare nut, or not tightening all connections.
3. Not trial testing each indoor unit individually.
4. Not reading technical data (temp/time/pressure/current) after the system is stabilized (normally the compressor needs
to run at least 10 minutes before reading the data). If the data is read too early, it may lead to inaccurate assessments
about the unit.
In an effort to help protect our customers from possible faulty installations that can lead to premature unit failure, YMGI
provides the above information for you (the owner) and the technician. You can observe while your system is being installed,
even though your observation is not a guarantee your system is being or has been installed properly and professionally.
With the information provided above, you will know some things to look for and questions you can ask. If at any time you
feel there may be an issue with the installation, please have your technician contact YMGI at [phone] x 703 with any
questions, issues or concerns you may have.

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INSTALLING TECHNICIAN/CONTRACTOR'S RESPONSIBILITIES
Discuss with the customer detailed information about the structure to be conditioned, local weather (typical design, extreme
temperature/humidity conditions, cooling and heating hours), previous and existing HVAC equipment (if any), usage and dependence on
new HVAC equipment or YMGI products.
Performing a cooling/heating load calculation by using commercially available professional programs/methods such as Right-J (Manual J)
for residential HVAC applications and Right-CommLoad (ASHRAE RTS/CLTD) for light commercial and commercial HVAC applications.
Contact your YMGI distributor/sales department or contact YMGI directly to obtain additional information to fully understand your YMGI
products, including but not limited to product features, cooling/heating performance at standard ratings/conditions and extreme conditions,
allowed indoor and outdoor temperature and humidity ranges, installation, operation, maintenance, service, warranty, parts and any other
issues pertaining to YMGI products.
Select the correct (most suitable) YMGI product unit models and accessories necessary for your HVAC applications and list them in the
proposal/quote, in writing, on company's quotation form or letterhead, based upon the information you collected from 1, 2 and 3 listed above.
5. List your currently valid HVAC license number and EPA number in your proposal/quote.
Make sure you are the only party to perform the entire installationand you will not sub-contract any part of the installation to any non-licensed
parties or persons. You will be solely responsible for the entire installation that you have been contracted.
Make sure you have all the materials you need to properly, completely and correctly finish the installation. The YMGI units and accessories
may be just a portion of what you will need for the project. When support issues arise, remember YMGI employees and YMGI
distributors/sales, dealers and agents are not installers and may only provide suggestions. You are the only one qualified to determine what
other materials you need to complete the installation.
When connecting electrical wires, follow all NEC, state and local codes and ensure the installation of all YMGI units and accessories meet
these requirements.
Connect the unit to a correctly sized electrical power source. If the unit is installed in an area where lightning or storms occur frequently, a
correctly sized and type of power surge protector must be installed between the outdoor unit and the power source.
Select the correct types and sizes of HVAC circuit breakers, disconnect switch boxes, wires and conduit from circuit breaker to disconnect
box and then from disconnect box to outdoor unit.
Select the proper location for installing indoor units and outdoor units with all factory requirements being followed (cooling/heating air inlets
and outlets are not blocked, or restricted, mounting structure is secure, installation for convenience is considered, allow adequate clearance
for maintenance/service and all applicable codes are met).
Cap/tape the two ends of every copper line before running them through any structure to keep any foreign substances from entering the
copper line causing contamination. Label the copper lines A-A, B-B, C-C, D-D, or any other identifying marks on each pair of copper lines
and wiring cable sets to keep from cross-piping or cross-wiring in multiple zone installations or where pipes for different single zone systems
are close to one another.
Secure the wiring cables that connect between the indoor unit and outdoor unit, following all applicable NEC, state and local codes for your
installation. If there are no special NEC, state or local codes to govern how these wires are to be installed, you can tape/cable tie them along
with insulated copper line.
Tighten all pipe and wire connections ensuring there is no leakage or false/loose connections.
Conduct a positive pressure leakage test, checking each of the inter-connecting copper lines between each indoor unit and outdoor unit by
charging with dry-nitrogen at the outdoor unit’s service port (NOTE: do not back-seat stopping valve). A liquid soap solution shall be
applied at all pipe connections to check for leakage. A 1/4” - 5/16” hose/valve adaptor may be needed if you have a 1/4” traditional manifold
hose connection.
If there is no positive leaking, then conduct a negative pressure leakage test, checking all inter-connecting copper lines between each indoor
unit and outdoor unit by pulling vacuum at the outdoor unit’s service port (NOTE: do not back-seat stopping valve) and checking that a
vacuum level of 500 Microns can be held for at least 60 minutes.
If there is no leakage found at any of the refrigeration pipe connections, flip up the indoor unit’s face panel and remove its filter, carefully pour
some clear water onto the up-right aluminum coil surface to test if the water can drain freely out of each of the indoor unit’s without finding
any leakage.
If there is water leakage found, locate the source of the leak and correct it. Only after everything is clear and all the necessary inspections
made, engage the correct electrical power to the system.
Then back-seat stopping valves of the outdoor unit to release refrigerant from the outdoor unit into the inter-connecting pipes and the indoor
unit.
Make sure both the indoor unit and outdoor unit are powered on correctly, operating the indoor unit in fan mode first. Then move on to test
cooling, dehumidifying/drying, heating and other modes.
Read refrigerant pressures and pipe/valve temperatures only after the system is stabilized (normally 10 minutes after cooling/heating mode
is started successfully). Record this data into the technician checklist in the lower half section of the Limited Product Warranty Registration
Card/Form.
Adjust refrigerant charging level (remove refrigerant if pipe is shorter, the temperature is colder; add refrigerant if pipe is longer the
temperature is warmer), following the manufacturer's instructions. If the average pipe length is shorter or longer than 25' and
pressure/temperature readings at the outdoor unit service valves are not falling into normal ranges.
Explain to the user/owner about proper unit operation and maintenance. Leave your contact information to allow them to reach you. If the
customer finds the unit does not work properly and cannot resolve the issue themselves, check the customer's units/parts/accessories and
correct the issue if there is one. Communicate with YMGI-technical support line at [phone] x 703, if further help if necessary.
Following these requirements will aid in ensuring that the units to be installed meet general HVAC practicing standards and necessary factory
requirements. Finding any possible problems early and preventing any further damage to the unit will help to ensure a properly working unit
for many years.

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LIMITED PRODUCT WARRANTY
Once the installation and successful testing of the system has been completely performed by a qualified licensed/certified
HVAC technician/contractor, the registration card/form is filled out completely and correctly, mailed and filed along with a
valid installation invoice from the contractor within 7 days of the original installation, the following standard Limited Product
Warranty is qualified: 10-years on the compressor and 5-year on PARTS ONLY. There is no labor coverage.
YMGI products are designed and manufactured free from defects in workmanship, and materials for normal use. However,
if for any reason, including occasionally transporting between YMGI factories/warehouses and your delivery location, you
discover the unit has issues, YMGI Group will help field a solution by following YMGI’s established warranty procedures:
Compressor: YMGI will warrant the compressor of a YMGI-validated and approved warranty filing, for a period of 10 years
from the date of successful installation at its original installation location.
Parts: YMGI will warrant parts of a YMGI-validated and approved warranty filing, for 5 years from the date of successful
installation at original installation location.
All warranty compressors and parts replaced will become the sole property of YMGI Group and must be returned upon
request. Warranty parts may be new or refurbished. All parts are tested and approved before shipping. At no time does
YMGI Group warrant labor cost of any type. Warranty will start from the date of a successful installation at the
original installation location, or 90 days as of original shipping date from YMGI Group, whichever comes first.
This is a standard limited liability warranty and DOES NOT cover the following:
Any damage or repairs to properties, or persons as an incident of or consequence of improper faulty transportation,
installation, operation, maintenance or service.
Any damage caused by frozen or broken water hoses or refrigeration pipes in the event of equipment failure.
Any damage due to floods, fire, wind, lightening, accidents, corrosive atmosphere.
Any damage due to interruption or inadequate electrical service to equipment.
Any products that are installed outside the US or Canada.
Any unit that has been moved from its original installation address.
Any labor costs associated with the installation or service of the unit.
Poor unit performance due to improper unit selection (SEER, Unit size).
To validate the above warranties, ALL of the following conditions must all be fulfilled:
1. The unit was fully (100%) and successfully installed by a licensed or certified HVAC technician.
2. The unit was installed following all NEC, state and local codes.
3. The unit was installed following all the information within the Instructions and User Manuals provided by YMGI Group.
4. ALL fields, especially the technician-checklist, of the Limited Warranty Registration Card/Form were filled out
completely by the installing technician and signed by both the installing company’s technician and the unit owner.
5. The Limited Warranty Registration Card/Form and a copy of the original installing company's invoice have been
received by YMGI Group-Warranty Dept., POB 1559, O'Fallon, MO 63366, within 7 days of successful installation.
No warranty filing will be validated or approved, if any one of the above conditions are not met. Product
registration does not guarantee the validity of this limited warranty statement.

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Steps to follow for warranty part replacement:
1. The installing or service technician must contact YMGI tech support at 1-866-833-3138 ext. 703 from the
installation location to check and confirm with YMGI Technical support the exact part(s) needed to fix the
problem(s).
2. YMGI will check the customer's warranty filing. There will be no charge for Parts with a validated and approved
warranty. Any Parts needed for warranties that have not been validated and approved or have an invalid warranty
filing (resulting in an unapproved warranty request), will be charged accordingly.
3. YMGI will ground ship the parts ASAP. Expedited shipping is available at the customer's expense.
4. Replacement parts that have an approved warranty registration are to be warranted for the remainder of the 5-
year on parts and a 10-year compressor warranty. Purchasing of replacement parts without a valid warranty filing
or unapproved warranty request, will be sold as is and are not covered by any warranty.
5. YMGI is continually improving products with various engineering changes and these changes are made without
prior notice. Such improvements or changes include but are not limited to product specification, appearance,
functionality, size, packaging, etc. These improvements or changes will not void the limited warranty stated herein.
YMGI is the final authority concerning this warranty policy.

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WHY DOES YMGI GROUP REQUIRE INSTALLATION AND SERVICE TO BE PERFORMED 100%
BY CURRENTLY LICENSED OR CERTIFIED HVAC TECHNICIANS/CONTRACTORS?
Expertise and Safety:
They have the training and experience to accurately and safely install and service your equipment. The equipment runs
with high-pressure refrigerant, oil and electrical current. The copper lines must be installed properly to prevent leakage
and foreign substances from contaminating the refrigerant system.
You will save money in the long run:
If any problem occurs with the unit that has been fully installed by a currently licensed or certified technician/contractor,
contact the original licensed or certified HVAC technician to evaluate the unit as they have the training and experience
to correct the problem quickly and efficiently. A technician may be unwilling to repair an issue on a unit that they did not
install. If you do find a technician willing to perform this service, there is an increased possibility of higher service fees,
increased service visits, or delayed service from that technician.
It's the law!
The federal, state and/or local government and authorities have various governing laws or regulations, guidelines,
ordinances, etc. These laws may require only licensed or certified professionals can install and service this type of high
pressure HVAC equipment.
SUGGESTIONS TO AID YOU IN HIRING AN HVAC CONTRACTOR:
Hire a currently practicing, licensed/certified HVAC professional technician/contractor. Technicians, who are no longer
practicing (retired, etc.) in this field, may not have current technical knowledge or may lack experience on the equipment
you have purchased.
Hiring a licensed technician to install your unit as a "side job" rather than a licensed HVAC company may pose possible
risk. This may result in an incomplete or unsatisfactory installation, no guarantee for workmanship and lack of
maintenance and further service to your unit.
Hire a technician/contractor who services customers in your local area and one you are familiar with. Local contractors
have a faster response time and it will be easier for you to determine if they are reputable.
Use only a reputable licensed/certified HVAC installation professional to prevent any unexpected charges because of
unethical business practices.
Check their references, verify they provide professional service for their customers. N.A.T.E or A.C.C.A certified
technicians are strongly recommended.
Some contractors/technicians maynot feel comfortable installing equipment that has been purchased by someone other
than themselves. You can contact YMGI directly to check and see if there are contractors in your area who have installed
our products or any similar products.
Ask for a detailed quote for the complete installation project. A flat rate quote is the safest contract for both you and the
contractor.
Local HVAC technicians may charge you on a project basis or on an hourly basis. It has been our general experience;
a full single head installation normally can cost $800 to $1500. These costs are estimates, and your actual costs
may differ due to your specific job requirements and installation location.
Number of hours can vary depending upon each individual situation, some factors are, but not limited to:
•Difficulty or complexity of securely installing the indoor unit.
•Difficulty or length of the inter-connecting pipes and wires to be installed.
A successful installation is dependent on all these suggestions and necessary steps are followed.
If the contractor(s)/technician(s) are experienced with the systems/brands you purchased. You might save on the
installation cost but remember to always ask for and verify references.
The contracts should list and detail all work to be performed and the standards they will follow. Some contractors are
willing to include a 1-year installation/service warranty at no extra charge. Check to see if this is an available option. If
available, make sure it is included in the contract.
Verify and confirm the installation is completed and all the unit functions have been tested and working properly. All
items on the checklist should be checked and clearly marked in the warranty registration card/form, prior to paying the
contractor in full.
The cost of not having your unit professionally installed can be more expensive than the additional cost of hiring a certified
contractor. Protect your investment and warranty eligibility by doing it right the first time.

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Safety Precautions
Follow these instructions to complete the necessary installation progress. Carefully read this manual before installation
and unit startup or servicing.
Wire size of power cord should be properly sized to meet the required electrical loads. Should the power cord get
damaged, the power cord should be replaced with a manufacturer approved cable.
After connecting the power cord, attach the electric box cover and secure properly.
Always meet the nitrogen charge requirements when welding pipes.
Never short-circuit or cancel the pressure switch as this will result in damage to the unit.
Connect the wired controller before energizing, otherwise the wired controller cannot be used.
Before using the unit, verify the piping and wiring are correct. This will avoid water leakage, refrigerant leakage, electric
shock, fire, etc.
Do not insert fingers or objects into the air outlet or inlet grille.
Open a door or window for ventilation for allowing fresh air to enter the room to avoid depleting the oxygen while gas/oil
supplied heating equipment is used during the installation.
Never start up or shut off the unit by means of directly plugging into or unplugging the power cord from the power outlet.
Turn off the unit after it runs at least five minutes, otherwise it will influence the oil return of the compressor.
Do not allow children to operate this unit.
Do not operate this unit with wet hands.
Turn off the unit or disconnect the power supply before cleaning the unit. This will avoid possible electric shock or
personnel injury.
Never spray or splash water towards the unit. This can cause a malfunction in the unit or can result in electric shock.
Do not expose the unit to moist or corrosive environments.
While operating in cooling mode, do not set the indoor unit room temperature too low. Keeping the temperature
difference between indoor and outdoor unit within 41°F (5°C).
YMGI Group recommends that only properly trained and authorized personnel be allowed to repair or service the unit.
Improper repairs or servicing can result in electric shock or fire hazards. Please contact YMGI Group if you need help
locating a qualified repair or service technician.
Before installation, check the power supply to ensure it is sufficient to meet and is in accordance with the requirements
specified on the nameplate of the unit. Ensure the power overload is functioning correctly and make sure it is properly
maintained.
Installation must be performed only by an authorized installer or HVAC professional in accordance with the requirements
set by the NEC and CEC. Do not attempt to install the unit yourself. Improper handling may result in water leakage,
electric shock, fire, and voiding of the warranty.
Be sure to use only approved accessories and parts to prevent water leakage, electric shock and fire.
Make sure the unit is grounded properly prior to connecting to power source, to avoid electric shock. Do not connect
the ground wire to a gas pipe, water pipe, lightning rod or telephone line.
Energize the unit for 8 hours before operation. Turn off or disconnect the power within 24 hours to prevent short cycling
(to protect the compressor).
If refrigerant leakage happens in a confined space during installation, ventilate immediately. Poisonous gases can occur
if the refrigerant gas is exposed to fire.
Volatile liquids, (such as paint thinners or solvents) if exposed to the unit’s surface will damage to the surface finish.
Only use a soft cloth along with a mild non-abrasive detergent to clean the outer casing of the unit.
If the unit does not operate normally or if you notice any type of burning odor, power off the unit and turn off the main
power supply, then immediately contact your YMGI authorized repair service center or HVAC professional.
YMGI Group will not be responsible for any personal injury or any property damage caused by improper or
incorrect installation, improper service or maintenance or by not following the instructions listed in this manual.

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BRIEF INTRODUCTION TO MINI SPLIT CEILING CASSETTE SYSTEM
Ceiling Mount Cassette Systems are designed for high performance, easy installation and service. Each system consists
of one or several indoor units and one outdoor unit, which are connected by one set or several sets of interconnected
refrigerant pipes and electric wires.
As shown in the following sample picture, air is drawn through the center grilles/filters and then discharged at 4 vents in
4 directions. In cooling mode, air passing through coil is cooled; in heating mode, air passing through coil is heated.
Sample Ceiling Cassette Mini Split System (For Continuous Engineering Improvement and Various Marketing
Needs and Actual Part Availability, Unit Appearance Subject to Change or Update Continuously without Prior
Notice)
The electrical and thermal power for the whole system comes from the outdoor unit. Electrical and thermal components
such as compressors and motors and heat exchange coils and others, are incorporated into the cabinet in an optimized
order. They can be either hung on the wall or installed on the ground. Once stacking or bracket kit is used, some outdoor
units can be stacked 2 or 3 units high, depending upon unit size and applications. Air is discharged horizontally, quietly
and smoothly. These units are a perfect fit in locations where installation and applications of general up-flow condensing
units are limited, such as apartments, condos, lofts, multi-families and high-rise buildings and others.
Indoor unit(s) delivers the thermal and acoustical comfort to the rooms. Air is drawn through the coil from the front or
topside and then discharged from the bottom. In cooling mode, air passing through coil is cooled; in heating mode, air
passing through coil is heated. Air is filtered or treated by the built in mechanism (washable or enzyme equipped or
electrostatic powered filter, varies from model to model), before being delivered into the room, with more than enough
comfort and care, at a wide angle (swing or not, varies from model to model).
Apartments
Offices, Restaurants, Gyms, etc.
Homes
NOTES:
Since ductless system is not designed to incorporate or use with ducted return or discharge tunnels, one single-zone unit
SHOULD NOT be used to take care of the cooling or heating load of more than one-story room. Several single-zone
ductless systems or multiple-zone ductless systems shall be proper in this regard.
These units are designed for applications at:
Residential
Light commercial
Institutional
Industrial
Commercial
Hospital

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Indoor Unit Diagram

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Specification Sheet
Items
Unit / Conditions
WMMS-12EC-V2B(59)2
WMMS-18EC-V2B(59)2
WMMS-24EC-V2B(59)2
Power Supply
Voltage/Ph/Hz
208-230/1/60
208-230/1/60
208-230/1/60
Allowed Voltage Range
187-253V
187-253V
187-253V
Cooling Capacity (Btu/h)
High/Standard/Low
13900/12000/5200
20800/17200/6200
26500/22800/9600
Heating Capacity (Btu/h)
ID 70/60, OD 47/43F
13000
18100
27400
ID 70/60, OD 17/15F
11600
16200
23800
ID 70/60, OD 17/5F
9000
13100
20600
SEER
Btu/h.W
16
16
16
HSPF
Btu/h.W
8.2
8.2
8.2
Dehumidifying Capacity
Pints/Hr.
2.96
3.8
5.28
Air Flow (CFM)
High/Medium/Low
353/312/245
353/312/245
694/522/366
Air-throw (Ft.)
Horizontal Installation
25-18 Upon Mounting
Height/Speed/Temp.
External Static Pressure
Water In.
0
0
0
Sound Level
Pressure dB(A) (H/M/L)
39/37/35
39/37/35
45/43/41
Power dB(A) (H/M/L)
49/47/45
49/47/45
55/53/51
Fan Motor
Model
FN11T-2
FN11T-2
FN35B-1
Shaft
Single
Single
Single
Speed (RMP, H/M/L)
700/600/515
700/600/515
570/520/280
Output (W)
11
11
50
Input (W)
50
50
165
Capacitor (uF)
1
1
3
Fan Wheel
Type-Piece
Centrifugal-1
Centrifugal-1
Centrifugal-1
Diameter x Height (In.)
11.1 x 5.8
11.1 x 5.8
17.7 x 4.4
Swing/Step Motor
Model
MP35CB
MP35CB
MP35CB
Piece
2
2
2
Output (W)
2
2
2
Input Power of
Elec. Heater
Type-W
NA
NA
NA
Electrical Protection Fuse
PCB / Transformer
T3.15A 250V / 0.2A
Evaporator Coil
Type
Aluminum Fin/Inner Grooved Copper Tube
Color
Blue
Copper Line Connections
Sealed by Dry Nitrogen
Yes
Yes
Yes
Flare/Nut-Liquid + Gas
1/4" + 3/8"
1/4" + 1/2"
1/4" + 5/8"
Drain Hose Connection
OD (In.)
1.22
1.22
1.22
Condensate Pump
Installed-Lift (In.)
Yes-25
Yes-25
Yes-25
Refrigerant Environmental
Friendly
R410A
Yes
Yes
Yes
Filter
Type-Feature
Standard-Washable
Standard-Washable
Standard-Washable
Size W x H (In.) / Qty.
13.56 x 13.13 / 1
13.56 x 13.13 / 1
21.38 x 21.34 / 1
Clean Coil Surface
Anti-Mildew Function
Yes
Yes
Yes
Pre-heating Function
Anti-Cold Blowing
Yes
Yes
Yes
Memory of
Previous Set-ups
Power is Lost/Resumed
Yes
Yes
Yes
Auto-Restart Function
If Power is Resumed
Yes
Unit Dimensions
Net L x W x H (In.)
22.4 x 22.4 x 9.1
22.4 x 22.4 x 9.1
33.1 x 33.1 x 9.4
Package L x W x H (In.)
33.4 x 28.7 x 12.2
33.4 x 28.7 x 12.2
37.8 x 37.8 x 12.2
Unit Weight
Net (LBs)
39.7
39.7
66
Packaged (LBs)
50.7
50.7
84
Face Panel Dimensions
Net L x W x H (In.)
25.6 x 25.6 x 2
25.6 x 25.6 x 2
37.4 x 37.4 x 2.4
Package L x W x H (In.)
28.7 x 26.4 x 4
28.7 x 26.4 x 4
40.9 x 40.4 x 4.5
Face Panel Weight
Net (LBs)
5.5
5.5
14
Packaged (LBs)
8.1
8.1
22
Notes:
1. Performance rated for matched system at standard conditions-cooling ID 80/67°F, OD 95°F; heating ID 70/60°F, OD 47/43°F,
25 ft. copper lines and IDU 7ft. above ODU. Unit performance varies when weather changes from the standard one.
2. Select equipment capacity sizes per space load calculation schedule and cooling & heating hours. Not to over size or under
size equipment.
3. Watch unit operation during extreme weather conditions in summer and winter. Wind baffle helps system cooling & heating
performance in low ambient temperature ranges.
4. Heating capacities up to 85% @ 17°F ambient temperature, up to 60% @ -4°F varying upon geographic location and actual
installation.

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UNIT DIMENSIONS
12k and 18k Btu/h units
Model
L
W
W1
W2
W3
W4
H
H1
H2
H3
H4
WMMS-12EC-V2B(59)2
25 19/32”
25 19/32”
23 5/8”
23 5/8”
16 3/8”
2 1/2”
9 3/32”
7 1/16”
1 27/32”
4 3/8”
5 5/32”
WMMS-18EC-V2B(59)2
25 19/32
25 19/32
22 13/32”
22 13/32
16 3/8”
2 1/2”
9 3/32
7 1/16”
1 27/32”
4 3/8”
5 5/32”
24k Btu/h units
Model
L
W
W1
W2
W3
W4
H
H1
H2
H3
H4
WMMS-24EC-V2B(59)2
37 13/32”
37 13/32”
33 3/32”
33 3/32”
9 13/32”
1 27/32”
4 3/8”
5 5/32

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Wiring Connections
WMMS-12EC-V2B(59)2, WMMS-18EC-V2B(59)2
WMMS-24EC-V2B(59) 2
Model
Power Supply
MCA (A)
MOP (A)
WMMS-12EC-V2B(59)2
208/230V-1ph-60Hz
1
15
WMMS-18EC-V2B(59)2
1
15
WMMS-24EC-V2B(59)2
1
15

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RECOMMENDED TOOLS FOR INSTALLATION
1. Mounting Indoor & Outdoor Units and
Running Piping/Wiring
Ruler
Stud-Finder
Dry-Wall Saw
Electric Drill
3” Hole Saw
Drill Extension
Hammer Drill and Bit
Measuring Tape
Level
Flash Light
Screw Driver (Phillips and Flat)
Hammer
Knife
Scissors
Goggled Glasses
Mask
Gloves
Ladder
2. Refrigeration Related Work
Flat Surface Wrench (Two)
Flare-Nut Tool Set
Hex Head Key Set
Torch for AC Application
Heat Absorption Flux
Nitrogen
Soap Bubble
Vacuum Pump
Helium Leakage Check
Manifold
3. Electrical Related Installation
Wire Cutter
Wire Stripper
Sharp Plier
Cable Ties
Black Tape for Electrical Use
Electrical Meter
4. Trial Running Units and Inspection
Clamp Meter
Manifold
Infrared Thermometer

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INSTALLATION NOTES
All Units Shall Be Installed by Licensed Contractors or Technicians.
Read Manuals before Installation.
•The location and structure should also be convenient for both installation and service.
•The location should NOT be where discharge air and noise could annoy a neighbor.
•The location should NOT be where drain may cause any damage to property or annoy a neighbor.
•The location should NOT be where brazing work may cause fire or smoke to the surrounding materials.
•The location should NOT be near flammable gases.
•The location should NOT be in or close to corrosive gases.
•The location should NOT be where children can access.
CAUTION & SUGGESTIONS TO FOLLOW PRIOR TO INSTALLATION
Check the unit for damage and missing parts or accessories. If there is damage is found or parts are found missing,
call the distributor right away.
Spin fan wheels or blades to check if they can rotate freely. If the fan wheel scratches the housing, call the distributor
right away and do not proceed with the installation until it is fixed.
Check the unit to make sure no foreign materials have been left inside the unit.
Check to be sure you have all the additional parts and accessories that are required for the installation and those
provided with the unit.
It is strongly recommended to only use YMGI supplied or approved parts and accessories.
Be sure a properly sized circuit breaker is installed for the electric power suppling the units.
Pre-build the support platform on the ground or bracket for the wall before or during construction and before
installation.
Read installation instructions for all units thoroughly.
Ask rep./distributor/YMGI Group anything you are not sure about.
Get your tools and parts ready and start the installation.
BASIC REQUIREMENTS FOR THE INSTALLATION LOCATION
Choose a location where there are no strong heat sources, vapors, flammable gas or volatile objects.
Choose a location where there are no high-frequency waves being generated by radio equipment, welders and
medical equipment.
Choose a location where there are not a lot of salinities. Avoid exposure to ocean spray near coastal areas.
Choose a location where there is no oil (machine oil) contained in the air.
Choose a location where there is no Sulfur gas present, such as areas close to hot springs.
Choose a location where there is no other special circumstance.
SELECTION OF INDOOR UNIT INSTALLING LOCATION
The air inlet and outlet vent should be far from any obstructions, making sure that the air can be blown through the
entire room.
Select a location where the condensate water can be easily drained, and can be easily connected to the outdoor unit.
Select a location where children cannot reach the unit.
Select a location that is strong enough to support the full weight of the unit and the vibration which will allow the unit to
operate more quietly.
Be sure to leave enough space to allow access for routine maintenance. The height of the installed location should be
80 inches or more from the floor.
Select a place about 3 feet or more away from television or any other electric appliances.
Select a place where the filter can be easily maintained.
Make sure that the indoor unit is installed in accordance with the dimensioned diagram.

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INSTALLATION ACCESSORIES
No.
Name
Image
Quantity
Notes
1
Drainage hose
1
For indoor side pipe joint
2
Clamp
1
For hole
3
Nylon fastener
4
L=200
4
Washer
10
10
5
Paper template for
installation
1
6
Screws
4
ST4.8*13-F
Use for Paper pad for
installation
7
Heat preservation
Sponge for pipe
2
Encase the tie-in
8
Big sealing pad
1
5*160*300
9
Sealing pad
1
5*45*300
v
10
Small sealing pad
2
3*30*150
11
Sealing bar
1
120*65*25
12
PVC tape
2
13
Screws
8
ST4.2 9.5PA
14
Remote control
1
For mounting the remote
control unit
15
Battery
2
AAA 1.5V
For remote control
16
Power control wire
1