Sterling VS - Manual (Page 20)

20
HAZARDOUS VOLTAGE!
disconnect ALL ELECTRIC
POWER INCLUDING REMOTE
DISCONNECTS BEFORE
SERVICING. Failure to
disconnect power before
servicing can cause severe
personal injury or death.
Standard units are shipped for use on 115 volt, 60
hertz single phase electric power. The motor nameplate
and electrical rating on the transformer should be
checked before energizing the unit heater electrical
system. All external wiring must conform to the latest
edition of the National Electric Code, ANSI/NFPA No. 70
and applicable current local codes; in Canada, to
the Canadian Electrical Code, Part 1 CSA Standard
C22.1.
Do not use any tools (i.e .
screwdriver, pliers, etc.) across the terminals to
check for power. Use a voltmeter.
It is recommended that the electrical power supply
to each unit heater be provided by a separate, fused
and permanently live electrical circuit. A disconnect
switch of suitable electrical rating for each unit
heater should be located as close to the controls
as possible. Each unit heater must be electrically
grounded in accordance with the latest edition of
the National Electric Code, ANSI/NFPA No. 70
or and applicable current local codes; In Canada to the
Canadian Electrical Code, Part 1, CSA C22.1. Sample
wiring connections are depicted in Figures 14 through
24.
OPERATION
Most basic unit heater systems are controlled by a room
thermostat. Locate thermostat on inner wall or column
so that optimum control could be obtained for that area.
Set thermostat for desired temperature.
On steam systems a low limit may be used to prevent
fan from blowing cold air unless the heater has steam
passing through the coil.
Small hot water systems could have the circulating
pump controlled directly by the room thermostat. On
large systems, zone valves could be used to control the
individual unit heater where constant water circulation is
used on the main system.
ELECTRICAL CONNECTIONS
THERMOSTAT WIRING AND LOCATION
NOTICE: The thermostat must be mounted on a
vertical vibration-free surface free from air currents
and in accordance with the furnished instructions.
Mount the thermostat approximately 5 feet (1.5 m) above
the floor in an area where it will be exposed to a free
circulation of average temperature air. Always refer to the
thermostat instructions as well as our unit wiring diagram
and wire accordingly. Avoid mounting the thermostat in
the following locations:
1. Cold areas - Outside walls or areas where drafts may
affect the operation of the control.
2. Hot areas - Areas where the sun’s rays, radiation,
or warm air currents may affect control operation.
3. Dead areas - Areas where air cannot circulate
freely, such as behind doors or in corners.
NOTICE: For all wiring connections, refer to the wiring
diagram on the motor nameplate (refer to pages 21
and 22). Should any original wire supplied with the
heater have to be replaced, it must be replaced with
wiring material having a temperature rating of at
least 105° C.
MOTORS
The standard 115/1/60 motors provided on Vertical Unit
Heaters are totally enclosed, Class “B” insulated and
have built-in thermal overload protection.
Vertical Units 40 through 72 use sleeve type bearings.
Vertical Units 125 through 285 use permanent split
capacitor motors with ball bearings.
All sleeve bearing motors have oil holes to allow
lubrication. Ball bearing motors are per manently
lubricated although some three phase or special motors
have removable plugs which will allow fi eld installation
of grease fi ttings.
The standard 40 through 104 motors can be converted
to variable speed operation with the addition of the solid
state speed control.
See Figures 10 through 24 for typical wiring diagrams.