General Information
RT-SVX35H-EN
11
Supply and Exhaust Airflow Proving Switches
(3S68 and 3S69)
3S68 is a binary input device used on CV & VAV
applications to signal the RTM when the supply fan is
operating. It is located in the supply fan section of the unit
and is connected to the RTM (1U48). During a request for
fan operation, if the differential switch is detected to be
open for 40 consecutive seconds; compressor operation is
turned "Off", heat operation is turned "Off", the request for
supply fan operation is turned "Off" and locked out,
exhaust dampers (if equipped) are "closed", economizer
dampers (if equipped) are "closed", and a manual reset
diagnostic is initiated.
3S69 is a binary input device used on all rooftop units
equipped with an exhaust fan. It is located in the exhaust
fan section of the unit and is connected to the RTM (1U48).
During a request for fan operation, if the differential switch
is detected to be open for 40 consecutive seconds, the
economizer is closed to the minimum position setpoint,
the request for exhaust fan operation is turned "Off" and
locked out, and a manual reset diagnostic is initiated. The
fan failure lockout can be reset; at the Human Interface
located in the unit's control panel, by Tracer, or by cycling
the control power to the RTM (1S70 Off/On).
Supply and Exhaust Fan Circuit Breakers
(1CB1, 1CB2)
The supply fan and exhaust fan motors are protected by
circuit breakers 1CB1 and 1CB2 respectively. They will trip
and interrupt the power supply to the motors if the current
exceeds the breaker's "must trip" value. The rooftop
module (RTM) will shut all system functions "Off" when an
open fan proving switch is detected.
Saturated Condenser Temperature Sensors
(2RT1 and 2RT2)
Are analog input devices used on CV & VAV applications
mounted inside a temperature well located on a
condenser tube bend. They monitor the saturated
refrigerant temperature inside the condenser coil and are
connected to the SCM/MCM (1U49). As the saturated
refrigerant temperature varies due to operating
conditions, the condenser fans are cycled "On" or "Off" as
required to maintain acceptable operating pressures.
Outdoor Air Humidity Sensor (3U63)
Is an analog input device used on CV & VAV applications
with 100% economizer. It monitors the outdoor humidity
levels for economizer operation. It is mounted in the fresh
air intake section and is connected to the RTM (1U48).
Return Air Humidity Sensor (3U64)
Is an analog input device used on CV & VAV applications
with the comparative enthalpy option. It monitors the
return air humidity level and compares it to the outdoor
humidity level to establish which conditions are best
suited to maintain the cooling requirements. It is mounted
in the return air section and is connected to the ECEM
(1U52).
Status/Annunciator Output
Is an internal function within the RTM (1U48) module on
CV & VAV applications that provides:
•
diagnostic and mode status signals to the remote
panel (LEDs) and to the Human Interface.
•
control of the binary Alarm output on the RTM.
•
control of the binary outputs on the GBAS module to
inform the customer of the operational status and/or
diagnostic conditions.
Space Pressure Transducer (3U62)
Is an analog input device used on CV & VAV applications
with the Statitrac option. It modulates the exhaust
dampers to keep the space pressure within the building to
a customer designated controlband. It is mounted in the
filter section just above the exhaust damper actuator and
is connected to the ECEM (1U52). Field supplied
pneumatic tubing must be connected between the space
being controlled and the transducer assembly.
Morning Warm-Up - Zone Heat
When a system changes from an unoccupied to an
occupied mode with the MWU option, the unit heater or
external heat (i.e. VAV reheat boxes) will be brought on if
the space temperature is below the MWU setpoint. The
heat will remain on until the temperature reaches the
MWU setpoint.
Supply Air Temperature Low Limit
Uses the supply air temperature sensor input to modulate
the economizer damper to minimum position in the event
the supply air temperature falls below the occupied
heating setpoint temperature.
Freezestat (4S12)
Is a binary input device used on CV & VAV units with
Hydronic Heat. It is mounted in the heat section and
connected to the Heat Module (1U50). If the temperature of
the air entering the heating coil falls to 40°F, the normally
open contacts on the freezestat closes signalling the Heat
Module (1U50) and the Rooftop Module (RTM) to:
Transducer Voltage Output vs Pressure Input
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
-0.5 0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Pressure (inches w.c.)
Volts
Summary of Contents for IntelliPak WEHE Series
Page 15: ...General Information RT SVX35H EN 15 Figure 1 Unit component layout and ship with locations...
Page 17: ...Installation RT SVX35H EN 17 Figure 2 Typical control module location...
Page 44: ...Installation 44 RT SVX35H EN Figure 27 Typical field power wiring for W_HE casings 2 through 6...
Page 56: ...Installation 56 RT SVX35H EN Figure 32 Wiring notes for CV controls...
Page 60: ...Installation 60 RT SVX35H EN Figure 35 Wiring notes VAV...
Page 68: ...System Start up 68 RT SVX35H EN Figure 38 Typical fenwall ignition control system...
Page 69: ...System Start up RT SVX35H EN 69 Figure 39 Typical Fenwall ignition control system...
