610.020-IOM (NOV 19)
Page 7
EVAPORATOR AND AIR COOLER
INSTALLATION - OPERATION - MAINTENANCE
NOTICE
Use copper conductors only.
WARNING
Before performing any service work on the equipment,
particularly in the vicinity of the fans or any other mov-
ing part, ensure that the correct electrical precautions
are adhered to. All electrical switchgear for the fans
must be disconnected, locked out and tagged out.
MOTOR WIRING
All external rotor motors are shipped with internal thermal
contacts. These contacts are not an internal overload pro-
tection device, but thermal contacts that open when over-
heated. The thermal contacts can be incorporated into the
control circuit wiring for added motor protection. Motor
start protection (MSP) and thermal overload protection
can be supplied upon request. NEMA motors are shipped
without internal overload protection, except for the AGBF
product line, but can be supplied upon request.
Branch circuit, feeder circuit, motor starters, overload
relays, and all wire sizes must be in accordance with all
applicable local and national codes.
FANS
The EC and ZA fans are essentially maintenance free and
are provided with durable lubrication appropriate to the
temperature range of their application. For NEMA motors,
periodic manual lubrication may be necessary according to
the maintenance schedule.
For thermal motor protection, use and wire the installed
thermo contacts according to the circuit diagram in the
submittal drawing package.
Refrigerant piping
Install all refrigerant piping and piping components in
accordance with either the IIAR Refrigeration Piping
Handbook (Ammonia or Carbon Dioxide) or the relevant
Systems and Practices chapters of the ASHRAE Handbook
(Halocarbons or Brines). Insulate all piping in accordance
with ASHRAE standards.
Units are supplied with multiple refrigerant connections,
factory sealed and pressurized to 30 psig (+/- 2 psig) to
remain sealed until ready for piping into the refrigeration
system. The connections on the units are not designed to
support any field piping or piping components. Design and
support field piping independent of the unit to minimize
the transmission of vibration and allow for thermal expan-
sion and contraction, and to inflict no load on the unit
connections.
Units with stainless steel tubes and piping are supplied
with black steel stubs at the end of each connection piece
to facilitate field piping or welding. These can be supplied
as stainless steel if required. Do not use the supplied con-
nections as a reference for system piping. Base the system
piping dimensions on industry accepted, good engineering
design principles.
For direct expansion units, select expansion valves in ac-
cordance with selection data and as required by expansion
valve manufacturer. Use expansion valves with external
equalizers. After the temperature has reached design
condition, adjust the expansion valve to obtain 8°F to 10°F
superheat at the suction line. For ammonia direct expan-
sion with superheating less than 18°F, use an electronic
expansion valve. Use suction traps when and if the suction
line rises above the unit cooler or heat exchanger.
Defrost piping
CONDENSATE DRAIN PIPING
Keep condensate drain lines as short as possible within the
refrigerated space and trap individually. Pitch all conden-
sate drain lines at a 3/8 in. inclination per linear ft (3 cm
inclination per linear m). Pipe drain lines from each unit to
an independent trap to prevent the migration of warm air
through the condensate drain lines. This is critical when
multiple units' drain lines are piped to a common drain line
header. The reverse flow (migration) causes ice buildup
in the drain pans if the room temperature is below 32°F
(0°C). This ice buildup blocks the drain outlet and traps the
condensate within the drain pan. Preferably, position traps
outside of freezer spaces and in warm locations. When
the trap is located in an area where the temperature never
drops below freezing, do not heat the trap. If heated, there
is a possibility of the condensate within the trap boiling off
and drying out the trap.
To prevent freezing, heat and insulate all condensate drain
piping and traps in spaces with temperatures below 34°F
(1°C). Heating elements must be energized continuously.
The values below are generally industry accepted for drain
line heater wattages:
+20°F (-7°C):
10W / linear ft (33 W/m)
0°F (-18°C): 20W / linear ft (65 W/m)
-20°F (-29°C): 30W / linear ft (100 W/m)
Ensure the condensate drain line sizing is the same dimen-
sion, at a minimum, as the outlet connection on the unit. A
union piped into the outlet from the unit is recommended
and enables disconnect of the drain line for heater repair,
replacement, and maintenance.
NOTICE
Always use two wrenches to fasten the condensate
drain pipe union. Do not apply torque to the fitting on
the drain pan.
WATER DEFROST PIPING
All water lines within refrigerated spaces must be insu-
lated and heat traced to prevent these lines freezing. Lines
must also be pitched up to 1/2 in. per linear ft to allow the
water to drain at the completion of the defrost period.
Install a solenoid valve in the water supply line to each
unit, which opens under the control of an automated timer
to allow water flow to the units. See the Water Defrost
section for more details on pipe sizing and control require-
ments.