99
JOHNSON CONTROLS
FORM 100.50-EG12 (918)
6.
Steam Heating Coil:
A steam heating coil shall be installed in the single package
unit discharge plenum.
Construction:
The steam coil shall be constructed in the non-freeze style. The
steam coil shall have six fins per inch, an 2-inch inlet, and 1-1/2-inch outlet connec-
tion. Tubes shall be 1-inch OD seamless copper tubing with a minimum wall thick-
ness of 0.035-inch and expanded into the fin collars for maximum fin-tube bond.
Inner distributing tubes shall be 5/8-inch OD seamless copper tubing with a minimum
wall thickness of 1/4 inch. All header connections shall be of red brass or steel, with
male pipe threads and silver braze to headers. Casing shall be galvanized steel. The
core shall be pitched in the direction of the condensate connection for proper drain-
age. Freezestat shall be provided to prevent coil freeze-up.
Testing:
The completed coil, including headers and connections, shall be tested
underwater with 325 pounds. compressed air to ensure a leak free coil.
7.
Diffuser Section:
For applications with an extended discharge plenum with down-
stream filtration or heating, a diffuser section is provided. A diffuser shall be included
to distribute the airflow from the fan evenly across the heating coil or filter bank to
optimize coil/filter life and effectiveness. The diffuser shall be sized for 50% free
area and provide adequate upstream and downstream clearance to minimize air
-
side pressure drop.
For Extended Discharge Plenums, Select One of the Following:
1.
Downstream Final Filter Rack:
A 12-inch rigid filter rack and filters shall be provid
-
ed downstream of the supply fan and diffuser segment for hospital applications. The
filter shall be 90–95% efficient MERV 14. A magnahelic pressure gauge shall be
included and visible from the outside of the unit for servicing and code compliance.
2.
Blank Section:
A blank section shall be provided downstream of the supply fan and
diffuser section.
Condenser Section
1.
Condenser Fans:
Condenser fans shall be matched up with compressors to op-
timize system control. Condenser fans shall be propeller type, directly driven by
permanently lubricated TEAO motor.
2.
Condenser Coil:
Microchannel condenser coils shall be constructed of parallel flow
aluminum alloy tubes metallurgically brazed to enhanced aluminum alloy fins. Coils
are configured in a V-bank configuration, with individual flat coils rotated from the
vertical plane for protection from hail damage for each condensing circuit. Condens-
ing coils shall have a subcooler for more efficient, stable operation.
3.
Compressors:
Units shall use industrial-duty hermetic scroll compressors, piped
and charged with P.O.E. oil and R-410A refrigerant. Compressors shall have an
enlarged liquid carrying capacity to withstand rugged operating conditions. Com
-
pressor frame shall be cast iron, with cast iron fixed and orbiting scrolls. Each com
-
pressor shall feature a solid state protection module, designed to protect the com-
pressor from over-temperature and over-current conditions. Compressors shall be
vibration-isolated from the unit, and installed in an easily accessible area of the unit.
All compressor-to-pipe connections shall be brazed to minimize potential for leaks.
Each compressor shall include a replaceable suction screen, discharge line check
valve, and oil sight glass.