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TAP INTO TOP OF MAIN
RETURN MAIN
LIFT NOT TO EXCEED 1 FT FOR
EACH POUND PRESSURE
DIFFERENCE BETWEEN STEAM
AND RETURN MAINS
SWING CHECK VALVE
STEAM TRAP WITH AIR VENT
STRAINER AND DRAIN VALVE
Figure 3 – Unit heater connections to overhead steam and return mains.
NOTES:
C.7 Wiring Schematics
1. This piping arrangement is only for two-position-type
control. Modulating steam control may not provide
Ruffneck
fan-forced unit heaters and heat exchangers may be
TM
sufficient pressure to lift condensate to return main.
TM
Ruffneck
fan-forced unit heaters and heat exchangers may be thermostatically controlled if required. Usually the flow of
TM
Ruffneck
thermostatically controlled if required. Usually the flow of heat
fan-forced unit heaters and heat exchangers may be thermostatically controlled if required. Usually the flow of
2. Do not use with fluids corrosive to steel.
transfer fluid is allowed to pass through the heat exchanger
heat transfer fluid is allowed to pass through the heat exchanger without interruption. The fan motor, in such cases, shuts
heat transfer fluid is allowed to pass through the heat exchanger without interruption. The fan motor, in such cases, shuts
3. Install using proper piping practices.
without interruption. The fan motor, in such cases, shuts on and
on and off by an electrical thermostat. Air flow through the heater is thus controlled. A small amount of heat will radiate
4. In horizontal pipe runs use eccentric reducers only.
on and off by an electrical thermostat. Air flow through the heater is thus controlled. A small amount of heat will radiate
off by an electrical thermostat. Airflow through the heater is thus
5. Use a properly sized steam trap.
from the heat exchanger when the fan is inoperative but this is usually tolerable. Absolute control of heat output from the
from the heat exchanger when the fan is inoperative but this is usually tolerable. Absolute control of heat output from the
controlled. A small amount of heat will radiate from the heat
heat exchanger would require that steam or flow of hot liquid to the heat exchanger be shut off. Such control of the heat
exchanger when the fan is inoperative but this is usually tolerable.
heat exchanger would require that steam or flow of hot liquid to the heat exchanger be shut off. Such control of the heat
transfer medium is possible by thermostatic valve control, separately or in combination with thermostatic fan control.
transfer medium is possible by thermostatic valve control, separately or in combination with thermostatic fan control.
Typically a manual shut-off valve is placed in the steam or liquid line for control purposes.
Typically a manual shut-off valve is placed in the steam or liquid line for control purposes.
FAN
FAN
MOTOR
MOTOR
THERMOSTATIC CONTROL FOR
THERMOSTATIC CONTROL FOR
NOTE:
Installation must comply with local electrical code.
–
–
For internal wiring of control devices and starters, consult
MOTOR C/W EXTERNAL
device manufacturer.
HIGH-LIMIT WIRES
MOTOR C/W EXTERNAL
HIGH-LIMIT WIRES
–
The thermostat must have an electrical rating equal to or
MOTOR
exceeding the HP, line voltage and current expected.
FAN
MOTOR
230 VOLT
5. Use a properly sized steam trap.
SHUT-OFF VALVE
THERMOSTATIC AIR
VENT OR PETCOCK.
(INSTALL IF TRAP DOES
PITCH
NOT HAVE AIR VENT)
DOWN
UNION
ELECTRICAL WIRING
ELECTRICAL WIRING
THERMOSTATIC CONTROL
for 115V, 1 Phase
SUPPLY VOLTAGE
NEUTRAL
SUPPLY VOLTAGE
NEUTRAL
115 VOLTS
115 VOLTS
1 PH
1 PH
115 VOLT
THERMOSTAT
115 VOLT
THERMOSTAT
115 VOLTS, 1 PHASE
115 VOLTS, 1 PHASE
FAN
3 POLE CONTACTOR RELAY
(NOT SUPPLIED)
3 POLE CONTACTOR RELAY
(NOT SUPPLIED)
EXTERNAL CONTROL PANEL
SHUT-OFF VALVE
PITCH DOWN
UNION
UNION
FULL SIZE DROP LEG
10.0 in. Min.
(254 mm)
6 in. (152mm) LONG
FULL SIZE
DIRT POCKET
Absolute control of heat output from the heat exchanger would
require that steam or flow of hot liquid to the heat exchanger be
shut off. Such control of the heat transfer medium is possible
by thermostatic valve control, separately or in combination with
thermostatic fan control. Typically a manual shut-off valve is placed
in the steam or liquid line for control purposes.
FAN
FAN
MOTOR
MOTOR
230 VOLT
230 VOLT
THERMOSTAT
THERMOSTAT
THERMOSTATIC CONTROL FOR
For wiring of fan motor, refer to diagram on the motor name
–
plate.
Some motors may be equipped with external high-limit wires.
–
These wires must be connected in series with the motor
SUPPLY
VOLTAGE
FAN
SUPPLY
control circuit. (see appropriate diagrams)
MOTOR
208/230
VOLTAGE
FAN
VOLTS
MOTOR
208/230
3PH
VOLTS
3PH
208/230 VOLT
CONTACTOR COIL
208/230 VOLT
CONTACTOR COIL
230 VOLT
NOTE:
1.
This piping arrangement is only for
two-position-type control. Modulating
steam control may not provide sufficient
pressure to lift condensate to return main.
2.
Do not use with fluids corrosive to steel.
3.
Install using proper piping practices.
4.
In horizontal pipe runs, use eccentric
reducers only.
5.
Use a properly sized steam trap.
THERMOSTATIC CONTROL
for 208/230V, 1 Phase
SUPPLY VOLTAGE
208/230V
1PH
(NOT SUPPLIED)
(NOT SUPPLIED)
EXTERNAL CONTROL PANEL
EXTERNAL CONTROL PANEL
(NOT SUPPLIED)
(NOT SUPPLIED)
THERMOSTATIC CONTROL FOR
208/230 VOLTS, 1 PHASE
208/230 VOLTS, 1 PHASE
208/230 VOLT
CONTACTOR COIL
3 POLE CONTACTOR RELAY
(NOT SUPPLIED)
3 POLE CONTACTOR RELAY
(NOT SUPPLIED)
EXTERNAL CONTROL PANEL
SUPPLY VOLTAGE
208/230V
1PH
208/230 VOLT
208/230 VOLT
CONTACTOR COIL
CONTACTOR COIL
SUPPLY VOLTAGE
208/230
SUPPLY VOLTAGE
VOLTS
208/230
3PH
VOLTS
3PH
208/230 VOLT
CONTACTOR COIL
7 7
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