JOHNSON CONTROLS
40
FORM 100.50-EG5 (108)
2. Barometric Relief Damper: Building air exhaust shall
be accomplished through barometric relief damp-
ers installed in the return-air plenum. The dampers
open relative to the building pressure. The opening
pressure shall be adjustable.
2. On/Off, Fan-Powered Exhaust: A DWDI Class I or
II forward-curved centrifugal exhaust fan shall be
provided to exhaust building return air to relieve
building static pressure. The fans shall be constant
volume and operate based on either a building static
pressure, or outside air-damper position.
2. Powered Exhaust with Modulating Discharge Damp-
er: A DWDI Class I or II forward-curved centrifugal
exhaust fan shall be provided to exhaust building
return air to relieve building static pressure. The
fans shall operate at a constant volume and operate
based on building static pressure. Exhaust airfl ow
shall be modulated via a parallel-acting, control
damper. The exhaust-air dampers shall be sized
for 100% of the exhaust airfl ow.
2. Powered Exhaust with Variable-Frequency-Drive: A
twin DWDI Class I or II forward-curved centrifugal
exhaust fan shall be provided to exhaust building
return air to relieve building static pressure. Exhaust
airfl ow shall be modulated via a factory-installed
and commissioned variable-frequency-drive with
the same nameplate horsepower as the supply fan
motor.
[FOR POWERED-EXHAUST OPTIONS ABOVE,
USE THE FOLLOWING]
3. Fan Motor: Fan motors shall be NEMA design ball-
bearing types with electrical characteristics and
horsepower as specifi ed. Motors shall be 1750
RPM, ODP [TEFC] open drip-proof type. The mo-
tor shall be located within the unit on an adjustable
base.
Mountings: Fan and fan motor shall be internally
mounted and isolated on a full width isolator sup-
port channel using 1-inch [2-inch] springs. The fan
discharge shall be connected to the fan cabinet
using a fl exible connection to insure vibration-free
operation.
Bearings and Drives: Fan bearings shall be self-
aligning, pillow block or fl anged type regreaseable
ball bearings and shall be designed for an average
life (L50) of at least 200,000 hours. All bearings shall
be factory lubricated and equipped with standard
hydraulic grease fi ttings and lube lines extended
to the motor side of the fan. Fan drives shall be
selected for a 1.5 service factor and antistatic belts
shall be furnished. All drives shall be fi xed pitch.
Fan shafts shall be selected to operate well below
the fi rst critical speed and each shaft shall be fac-
tory coated after assembly with an anticorrosion
coating.
Filter Section:
[SELECT A FILTER RACK, FILTER MEDIA, AND
SWITCH IF DESIRED]
1. Angled Filter Rack: two-inch throwaway fi lters shall
be provided in an angled fi lter rack.
1. Angled Filter Rack: two-inch carbon media fi lters
shall be provided in an angled fi lter rack.
1. Angled Filter Rack: two-inch cleanable fi lters shall
be provided in an angled fi lter rack.
1. Angled Filter Rack: two-inch high-effi ciency (30%)
pleated fi lters shall be provided in an angled fi lter
rack.
1. Flat Filter Rack: 60-65% effi cient rigid fi lters with a
two-inch, high-effi ciency pleated pre-fi lters shall be
provided in a fl at fi lter rack.
1. Flat Filter Rack: 90-95% effi cient rigid fi lters with a
two-inch, high-effi ciency pleated pre-fi lters shall be
provided in a fl at fi lter rack.
2. Dirty Filter Alarm: A dirty-fi lter switch shall be pro-
vided and wired to the rooftop unit control panel.
Upon closure of the switch, the controller shall
display a dirty-fi lter fault. The setting of the switch
can be changed manually to close at a specifi ed
pressure drop across the fi lters.
Evaporator Section
1. Cooling Coil: Evaporator coils shall be direct-expan-
sion type with intertwined circuiting to assure com-
plete coil-face activity during part-load operation.
Coil tubes shall be 3/8” OD copper, with internally
enhanced tubes. Fins shall be enhanced mechani-
cally expanded to bond with the copper tubes.
Coil casing shall be fabricated from heavy-gauge
galvanized steel. All coils shall be pressure tested
at a minimum of 450 PSIG.
2. IAQ Drain Pan: The main coil drain pan shall be
double-sloped with a condensate connection
through the base rail of the unit. Clearance between
the evaporator coil and the drain pan shall allow
for easy access to the drain pan for cleaning, and
shall be visible for inspection without the removal
of components.
3. Intermediate Drain Pan: Coils with fi nned height
greater than 48” shall have an intermediate drain
pan extending the entire fi nned length of the coil.
Guide Specifi cations
(continued)
