349687-JTG-A-1007
Johnson Controls Unitary Products
37
GUIDE SPECIFICATIONS
GENERAL
Units shall be manufactured by Johnson Controls in an ISO
9001 certified facility.
Series 20 J**DJ units are convertible single package units. All
models have dual independent refrigerant circuits for efficient
part load operation and maximum comfort control. Although
the units are primarily designed for curb mounting on a roof,
they can also be slab-mounted at ground level or set on steel
beams above a finished roof. Cooling only, cooling with gas
heat and cooling with electric heat models are available with
a wide variety of factory-mounted options and field-installed
accessories to make them suitable for almost every applica-
tion. All units are self-contained and assembled on full perim-
eter base rails with holes in the four corners for overhead
rigging. Every unit is completely piped, wired, charged and
tested at the factory to simplify the field installation and to
provide years of dependable operation. All models (including
those with an economizer) are suitable for either bottom or
horizontal duct connections. Models with power exhaust are
suitable for bottom duct connections only. For bottom duct,
remove the sheet metal panels from the supply and return air
openings through the base of the unit. For horizontal duct,
replace the supply and return air panels on the rear of the unit
with a side duct flange accessory. All supply air blowers are
equipped with a belt drive that can be adjusted to meet the
exact requirements of the job. A high static drive option is
available for applications with a higher CFM and/or static
pressure requirement.
Each unit shall have 4 condenser fan motors. All compres-
sors include crankcase heat and internal pressure relief.
Every refrigerant circuit includes an expansion valve, a liquid
line filter-drier, a discharge line high pressure switch and a
suction line with a freezestat and low pressure/loss of charge
switch. The unit control circuit includes a 75 VA transformer,
a 24-volt circuit breaker and a relay board with two compres-
sor lockout circuits, a terminal strip for thermostat wiring, plus
an additional set of pin connectors to simplify the interface of
additional field controls. All units have long lasting powder
paint cabinets with 750 hour salt spray test approval under
ASTM-B117 procedures.All models are CSA approved. All
models include a 1-year limited warranty on the complete
unit. Compressors and electric heater elements carry an
additional 4-year warranty. Aluminized steel tubular heat
exchangers carry an additional 9-year warranty.
DESCRIPTION
Units shall be factory-assembled, single packaged, J**DJN
Electric Cooling/Gas Heat, J**DJC/E Electric Cooling/
Optional Electric Heat, designed for outdoor mounted instal-
lation. The 15,17.5, and 20 ton units shall have minimum
EER ratings of 11.1. The 25 ton unit shall have a minimum
EER rating of 10.5.
They shall have built-in field convertible duct connections for
down discharge supply/return or horizontal discharge supply/
return, and be available with factory installed options or field
installed accessories. The units shall be factory wired, piped,
charged with R-22 refrigerant and factory tested prior to ship-
ment. All unit wiring shall be both numbered and color coded.
All units shall be manufactured in a facility certified to ISO
9001 standards and the cooling performance shall be rated in
accordance with DOE and ARI test procedures. Units shall
be CSA listed, classified to ANSIZ21.47 standards, UL 1995/
CAN/CSA No. 236-M90 conditions.
UNIT CABINET
Unit cabinet shall be constructed of a combination of G60 and
G90 galvanized steel, with exterior surfaces coated with a
non-chalking, powdered paint finish, certified at 750 hours
salt spray test per ASTMB117 standards. Indoor blower sec-
tion shall be insulated with a minimum 1/2" thick insulation,
coated on the airside. Aluminum foil faced insulation shall be
used in the furnace compartment and be fastened with ridged
fasteners to prevent insulation from entering the air stream.
Cabinet panels shall be "large" size, easily removable for ser-
vicing and maintenance. Full perimeter base rails shall be pro-
vided to assure reliable transit of equipment, overhead rigging
and proper sealing on roof curb applications. Disposable 2" fil-
ters shall be furnished and be accessible through a removable
access door, sealed airtight. Units filter track shall be designed
to accommodate either 1" or 2" filters. Fan performance mea-
suring ports shall be provided on the outside of the cabinet to
allow accurate air measurements of evaporator fan perfor-
mance without removing panels or creating air by-pass of the
coils. Condensate pan shall be internally sloped and conform
to ASHRAE 62-89 self-draining standards. Condensate con-
nection shall be a minimum of 1" I.D. female and be a ridged
mount connection. Unit shall incorporate a fixed outdoor air
damper with an outdoor air intake opening covered with a bird
screen and a rain hood painted to match the exterior of the
unit.
INDOOR (EVAPORATOR) FAN ASSEMBLY
Fan shall be a belt drive assembly and include an adjustable-
pitch motor pulley. Job site selected (B.H.P.) brake horsepower
shall not exceed the motors nameplate horsepower rating, plus
the service factor. Units shall be designed not to operate above
service factor. Fan wheel shall be double-inlet type with for-
ward-curved blades, dynamically balanced to operate smoothly
throughout the entire range of operation. Airflow design shall be
constant air volume.
A variable air volume (VAV) option using a variable frequency
drive (VFD) is available for applications requiring a constant
supply duct static pressure. Units equipped for VAV shall be
controlled by a duct pressure transducer with a 0 - 5” WC
pressure range. The pressure transducer shall provide a 0 - 5
VDC output signal to a VAV control board which, in turn shall
provide a 2 - 10 VDC speed reference signal to the VFD. The
VAV control board shall operate using factory-installed Sup-
ply Air, Return Air and Outside Air Temperature Sensors.
