46
Step 3 — Make Electrical Connections —
Refer
to unit nameplate for required supply voltage, fan and heater
amperage and required circuit ampacity. Refer to unit wir-
ing diagram for unit and field wiring. Since each project is
different and each unit on a project may be different, the in-
staller must be familiar with the wiring diagram and name-
plate on the unit before beginning any wiring. Make sure all
electrical connections are in accordance with unit wiring di-
agram and all applicable codes. The type and sizing of all
wiring and other electrical components such as circuit
breakers, disconnect switches, etc. should be determined by
the individual job requirements, and should not be based on
the size and/or type of connection provided on the equip-
ment. All installations should be made in compliance with
all governing codes and ordinances. Compliance with all
codes is the responsibility of the installing contractor.
The fan motor(s) should never be controlled by any wiring
or device other than the factory-supplied switch or thermostat/
switch combination unless prior factory authorization is
obtained. Fan motor(s) may be temporarily wired for use
during construction only with prior factory approval and only
in strict accordance with the instructions issued at that time.
All components furnished for field installation by either the
factory or the controls contractor should be located and
checked for proper function and compatibility. All internal
components should be checked for shipping damage, and any
loose connections should be tightened to minimize problems
during start-up.
Any devices such as fan switches or thermostats that have
been furnished from the factory for field installation must be
wired in strict accordance with the wiring diagram that appears
on the unit. Failure to do so could result in personal injury or
damage to components, and will void all manufacturer's
warranties.
Units with factory-supplied and factory-installed aquastats
may be shipped with the aquastats mounted on a coil stub-out.
If this is the case, remove the aquastat before installing valve
package. When reinstalling aquastats, consult the factory-
piping diagram in the submittal for proper location. If the valve
package is field-supplied, the aquastat must be installed in a
location where it will sense the water temperature regardless of
the control valve position. A bleed bypass may be required to
guarantee proper aquastat operation. The aquastat bypass line
allows a small amount of water to flow from the supply to the
return piping when the control valve is closed.
FACTORY-INSTALLED OPTIONS
Condensate Overflow Switch — The condensate overflow
switch is used to detect a clogged condensate drain pan. The
condensate switch uses a normally closed contact to allow the
system control power to pass through the switch energizing the
water valves and fans allowing normal operation. When an
overflow condition is detected by the switch, it opens the NC
contact and de-energizes the water valve and fans.
Aquastat — The aquastat must be able to sense whether the
flowing water is being chilled or heated and switches a contact
closed to provide automatic summer or winter changeover for
the system. When a two-pipe cooling/heating system with
optional auxiliary electric heat is desired, an additional
aquastat is required.
Units with optional factory furnished and installed aquastats
may be shipped with aquastats mounted on the coil stub out. In
this situation, remove the aquastat before valve package instal-
lation. Refer Fig. 35 for factory piping diagram for proper loca-
tion when reinstalling the aquastats. If the valve package is
field supplied the aquastat must be installed in a location where
it will sense the water temperature regardless of control valve
position. A bleed bypass should be provided for proper opera-
tion of aquastat. The bleed line allows a small amount of water
to flow from supply to return piping when the control valve is
closed for loop temperature sensing.
All field wiring must be in accordance with governing
codes and ordinances. Any modification of unit wiring without
factory authorization will invalidate all factory warranties and
nullify any agency listings. The manufacturer assumes no re-
sponsibility for any damages and/or injuries resulting from im-
proper field installation and/or wiring.
Units may be equipped with line voltage controls or
24 VAC control systems. The following descriptions are for
typical control sequences only. For detailed control operating
sequence, refer to thermostat operating instructions.
STANDARD WIRING PACKAGES
Manual Fan Control — On vertical cabinet units, a fan-speed
switch may be furnished unit-mounted and wired. On vertical
furred-in units and horizontal units, the switch may be shipped
separately on a decorative wall plate for field mounting and
wiring.
The standard switch has LOW, MEDIUM, HIGH and OFF
positions plus an auxiliary contact to energize thermostats,
valves, dampers, etc.
NOTE: Wiring diagrams are for typical applications. If other
voltages for heaters or controls are specified, wiring may differ
from that shown. Refer to wiring diagram on unit blower hous-
ing for unit specific wiring.
Thermostatic Electric Valve Control, 2-Pipe — A thermo-
statically controlled 2-position valve provides superior control
to fan cycling. With this control, the fan runs continuously un-
less it is manually switched to the OFF or AUTO position. The
fan must be on before the valve can be opened to supply water
to the coil.
This system can be used for normal 2-pipe changeover systems
and can also be furnished for cooling-only or heating-only ap-
plications by omitting the changeover and specifying which
application is intended. Wiring diagrams show typical applica-
tions. Refer to wiring diagram on unit blower housing for unit
specific wiring.
Thermostatic 2-Pipe Auxiliary Electric Heat with Valve Con-
trol — This system, also called twilight or intermediate season
electric heat, goes a long way towards solving the spring and
fall control problems of 2-pipe systems.
Chilled water can be run late into the fall, turned on early in
the spring and electric heat will still be available to all units
whenever required.
Field
Tubing
Wet Rag
Torch
Supply
or
Return
Adaptor
(Factory Installed)
Stub
From Coil
Fig. 40 — Field Piping Connections
IMPORTANT: Refer to unit wiring label for specific
functions. Standard wiring diagram configurations are
maintained in separate Fan Coil Wiring Diagram litera-
ture.
