
WARNING:
HAZARDOUS VOLTAGE - DISCONNECT POWER and DISCHARGE
CAPACITORS BEFORE SERVICING
4YCZ6-IG-8-EN
18-EB28D1-8-EN
Installer's Guide
Single Packaged Gas/Electric 16 SEER
Convertible, 3 - 5 Ton, 60 - 115 KBTU
R-410A
ALL phases of this installation must comply with NATIONAL, STATE AND LOCAL CODES
IMPORTANT — This Document is customer property. Please return to service information pack and give this Installer's Guide to the homeowner
upon completion of work.
4YCZ6036 through 4YCZ6060
SAFETY HAZARD!
This information is for use by individuals having adequate
backgrounds of electrical and mechanical experience. Any
attempt to repair a central air conditioning product may result
in personal injury and/or property damage. The manufacturer
or seller cannot be responsible for the interpretation of this
information, nor can it assume any liability in connection
with its use.
HAZARDOUS GASSES!
Exposure to fuel substances, or by-products of incomplete
fuel combustion, is believed by the state of California to cause
cancer, birth defects, or other reproductive harm.
This warning complies with State of California law, Proposition 65.
This product must be gas piped by a Licensed Plumber or
Gas Fitter in the Commonwealth of Massachusetts.
HAZARDOUS VOLTAGE, MOVING PARTS, AND GAS!
Bodily injury can result from high voltage electrical components, fast moving fans, and combustible gas. For protection
from these inherent hazards during installation and service,
the electrical supply must be disconnected and the main
gas valve must be turned off. If operating checks must be
performed with the unit operating, it is the technician's responsibility to recognize these hazards and proceed safely.
SAFETY HAZARD!
Do not operate the unit without the evaporator fan or coil
access panels in place. Reinstall the access panels after
performing maintenance proceedures on the fan. Operating
the unit without the access panels properly installed may
result in severe personal injury or death.

Installer’s Guide
Safety Considerations
IMPORTANT: Read this entire manual before beginning installation procedures.
NOTICE
Warning and Cautions appear at appropriate
locations throughout this guide. Read these
carefully.
WARNING: INDICATES A POTENTIALLY HAZARDOUS SITUATION WHICH, IF NOT AVOIDED,
COULD RESULT IN DEATH OR SERIOUS INJURY.
CAUTION: Indicates a potentially hazardous situation
which, if not avoided, may result in minor or moderate injury. It may also be used to alert against unsafe practices
and where property-damage-only accidents could occur.
This product contains fiberglass wool insulation! Fiberglass
dust and ceramic fibers are believed by the state of California
to cause cancer through inhalation. Glasswool fibers may
also cause respiratory, skin, or eye irritation.
PRECAUTIONARY MEASURES
• Avoid breathing fiberglass dust
• Use a NIOSH approved dust/mist respirator
• Avoid contact with the skin or eyes. Wear long-sleeved,
loose fitting clothing, gloves, and eye protection.
• Wash clothes separately from other clothing, rinse
washer thoroughly.
• Operations, such as sawing, blowing, tear-out, and
spraying may generate fiber concentrations requiring
additional respiratory protection. Use the appropriate
NIOSH approved respirator in these situations.
FIRST AID MEASURES
Eye Contact: Flush eyes with water to remove
dust. If symptoms persist, seek medical
attention.
Skin Contact: Wash affected area gently with soap and
warm water after handling.
EXPLOSION HAZARD!
Propane gas is heavier than air and may collect in any low
areas or confined spaces. In addition, odorant fade may make
the gas undetectable except with a warning device. If the
gas furnace is installed in a basement, an excavated areas
or a confined space, it is strongly recommended to contact
a gas supplier to install a gas detecting warning device in
case of leak. The manufacturer of your furnace does not test
any detectors and makes no representations regarding any
brand or type of detector.
EXPLOSION HAZARD!
To prevent an explosion or possible injury, death, and equipment damage, do not store combustible materials, gasoline,
or other flammable vapors or liquids near the unit.
Page 2
CONTAINS REFRIGERANT!
SYSTEM CONTAINS OIL AND REFRIGERANT UNDER
HIGH PRESSURE. RECOVER REFRIGERANT TO RELIEVE
PRESSURE BEFORE OPENING SYSTEM. Failure to follow
proper procedures can result in personal illness or injury
or severe equipment damage.
RECONNECT ALL GROUNDING DEVICES.
All parts of this product that are capable of conducting
electrical current are grounded. If grounding wires, screws,
straps, clips, nuts, or washers used to complete a path to
ground are removed for service, they must be returned to
their original position and properly fastened.
Unit contains R-410A Refrigerant!
R-410A operating pressure exceeds the limit of R-22. Proper
service equipment is required. Failure to use proper service
tools may result in equipment damage or personal injury.
SERVICE
Use only R-410A Refrigerant and approved POE compres-
sor oil.
Hot Surface!
Do Not touch top of compressor. May cause minor to severe
burning.
Never use combustible cleaning fluids on any part of the
furnace.
Caution must be taken at all times to avoid personal injuries
and/or damage to equipment.
IMPORTANT: This product has been designed and manufactured
to meet ENERGY STAR criteria for energy efficiency. However,
proper refrigerant charge and proper air flow are critical to
achieve rated capacity and efficiency. Installation of this product
should follow the manufacturer’s refrigerant charging and air flow
instructions. Failure to confirm proper charge and airflow may
reduce energy efficiency and shorten equipment life.
IMPORTANT: Do not connect gas piping to the unit until a line pres-
sure test has been completed. This unit should never be exposed to
gas line pressure in excess of 14 inches water column (1/2 PSIG).
The furnace and its equipment shutoff valve must be disconnected
from the gas supply piping system during any pressure testing of
that system at test pressures in excess of 1/2 psi.
IMPORTANT: Reconnect all grounding devices. All parts of this
product capable of conducting electrical current are grounded. If
grounding wires, screws, straps, clips, nuts, or washers used to
complete a path to ground are removed for service, they must be
returned to their original position and properly fastened.
IMPORTANT: Wear appropriate gloves, arm sleeve protectors,
and eye protection when servicing or maintaining this equipment.
IMPORTANT: Air filters and media wheels or plates shall meet the test
requirements in UL 900.

Installer’s Guide
Contents
Safety Considerations 2
Introduction 3
Step 1-Inspect Shipment 3
Step 2-Determine Unit Clearances 4
Step 3-Review Location and Recommendation
Information 10
Step 4-Unit Installation 11
Install Flue Hood 11
Ground Level Installation 11
Rooftop Installation -- Curb Mounting 11
Covert Horizontal Airflow to Down Airflow 11
Install Full Perimeter Roof Mounting Curb 11
Lifting and Rigging 12
Placing the Unit on the Mounting Curb 12
Rooftop Installation -- Frame Mounting 13
Rooftop Installation -- No Frame/Curb 13
Ductwork Installation 16
Attaching Downflow Ductwork to Roof Curb 16
Attaching Downflow Ductwork to Roof Frame 16
Attaching Horizontal Ductwork to Unit 16
Condensate Drain Piping 16
Gas Piping Installation 16
Pipe Delivery Schedule (natural gas only) 17
Gas Pressure Set-up Precautions 17
Gas Supply Line Pressure (all fuels) 17
Verify Manifold Pressure 18
Input Check and Adjustment 18
High Altitude Installation 19
Air Filter Installation 19
Electrical Wiring 19
Electrical Connections 18
Electrical Power 19
Disconnect Switch 19
Over current Protection 19
Power Wiring 19
Control Wiring (Class II) 20
Thermostat Heat Anticipator 20
Step 5-Unit Startup 20
Pre-start Quick Checklist 20
Field Wiring Diagram 21
Starting the Unit in the Cooling Mode 22
Operating Pressures 22
Voltage Check 22
Cooling Shutdown 22
Starting the Unit in Gas Heating Mode 22
Final Installation Checklist 22
Sequence of Operation 23
Maintenance 24
Owner Maintenance 24
Filters 24
Service Maintenance 25
Cooling Season 24
Heating Season 24
Manifold Pressure Check and Adjust 25
Flue Hood and Combustion Blower Cleaning 25
Status LEDs 26
Introduction
Read this manual carefully before attempting to install, operate, or perform maintenance on this unit. Installation and
maintenance should be performed by qualified service technicians only. Do NOT use this furnace for temporary heating of
buildings under construction.
As shipped from the factory, this unit is for use with natural gas
only. It is listed by Underwriters Laboratory. An LP Gas conversion kit is available. Extreme mounting kits for slab and curbs
are also available.
Packedaged units are designed for outdoor mounting with a
vertical condenser discharge. They can be located either at
ground level or on a roof in accordance with local codes or
National Fuel Gas Code (ANSI-Z223.1A) Latest Revision.
Since these units are designed exclusively for outdoor operation, additional flue venting systems are not required. Each
unit contains an operating charge of refrigerant as shipped.
Extreme mounting kits are available for slab (BAYEXMK003A), utility curb (BAYEXMK002B), or curb (BAYEXMK001A) mountings.
This guide is organized as follows:
Step 1- Inspect Shipment
Step 2- Determine Unit Clearances
Step 3- Review Location and Recommendation Information
Step 4- Unit Installation
Step 5- Unit Startup
Sequence of Operation
Maintenance
Step 1—Inspect Shipment
1. Check for damage after the unit is unloaded. Report promptly
to the carrier any damage found to the unit. Do not drop the
unit.
IMPORTANT: To prevent damage to the sides and top of
the unit when hoisting, retain the top shipping skid on the
unit or use “spreader bars” as shown on page 14.
2. Check the unit nameplate to determine if the unit is correct for
the intended application. The power supply must be adequate
for the unit and all accessories.
3. Check to be sure the refrigerant charge has been retained
during shipment. Remove the Compressor access panel to
access the 1/4" flare pressure taps.
4. The Flue Hood is included with the unit's literature pack.
5. If this unit is being installed on a curb, verify that the correct
curb is provided for the unit.
•4YCZ6036 uses model BAYCURB050.
•4YCZ6048 and 4YCZ6060 use model BAYCURB051.
6. If the unit is being hoisted, accessory kit BAYLIFT002B is
recommended. It includes a kit of four (4) lifting lugs and
instructions.
NOTE: If practical, install any internal accessories to the
unit at the shop.
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Installer’s Guide
Step 2—Determine Unit Clearances
Figures 1 through 6 show the unit critical dimensions.
NOTE: The view labeled “Bottom
Side” represents the Base
as viewed looking up from
underneath the unit.
Figure 1. 4YCZ6036 (1 of 3)
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Installer’s Guide
NOTE: The view labeled “Bottom
Side” represents the Base
as viewed looking up from
underneath the unit.
Figure 4. 4YCZ6048 through 4YCZ6060 (1 of 3)
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