RT-SVX24Q-EN
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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.
Discharge Line Thermostat for Evaporative
Condensers
The first compressor on each circuit is equipped with a
Discharge Line Thermostat. If the temperature of the
line exceeds 210°F the thermostat interrupts the 115V
circuit for the compressors and both of the
compressors on that circuit will be de-energized. Once
the temperature drops below 170°F the thermostat will
close and allow the compressor to be energized.
Freezestat
A binary input device used on CV and VAV units with
Hydronic Heat. It is mounted in the heat section and
connected to the Heat Module . If the temperature of
the air leaving the heating coil falls to 40°F, the
normally open contacts on the freezestat closes
signalling the Heat Module and the Rooftop Module
(RTM) to:
•
drive the Hydronic Heat Actuator to the full open
position
•
turn the supply fan “Off”
•
close the outside air damper
•
turn “On” the SERVICE light at the Remote Panel
•
initiate a “Low Temp Limit” diagnostic to the
Human Interface
Compressor Circuit Breakers
The Scroll Compressors are protected by circuit
breakers which interrupt the power supply to the
compressors if the current exceeds the breakers “must
trip” value. During a request for compressor operation,
if the Compressor Module detects a problem outside
normal parameters, it turns any operating compressor
(s) on that circuit “Off”, locks out all compressor
operation for that circuit, and initiates a manual reset
diagnostic (compressor trip).
Constant Volume (CV) Units
Zone Temperature — Cooling
Relies on input from a sensor located directly in the
space, while a system is in the occupied “Cooling”
mode. It modulates the economizer (if equipped) and/
or stages the mechanical cooling “On and Off” as
required to maintain the zone temperature to within the
cooling setpoint deadband.
Zone Temperature — Heating
Relies on input from a sensor located directly in the
space, while a system is in the occupied “Heating”
mode or an unoccupied period, to stage the heat “on
and off” or to modulate the heating valve (hydronic
heat only) as required to maintain the zone
temperature to within the heating setpoint deadband.
The supply fan will be requested to operate any time
there is a request for heat. On gas heat units, the fan
will continue to run for 60 seconds after the furnace is
turned off.
Supply Air Tempering
On CV units equipped with staged gas heat, if the
supply air temperature falls 10°F below the occupied
heating setpoint temperature while the heater is “Off”,
the first stage of heat will be turned “On”. The heater is
turned “Off” when the supply air temperature reaches
10°F above the occupied heating setpoint temperature.
Variable Air Volume (VAV) Units
Occupied Heating — Supply Air Temperature
When a VAV unit is equipped with “Modulating Heat”,
and the system is in an occupied mode, and the field
supplied changeover relay contacts have closed or per
a BAS command, the supply air temperature will be
controlled to the customer specified supply air heating
setpoint. It will remain in the heating status until the
changeover relay contacts are opened or BAS has
released the heat command.
Occupied Cooling — Supply Air Temperature
When a VAV unit is in the occupied mode, the supply
air temperature will be controlled to the customer
specified supply air cooling setpoint by modulating the
economizer and/or staging the mechanical cooling “On
and Off” as required. The changeover relay contacts
must be open, or BAS command set to auto or cool, for
the cooling to operate.
Daytime Warm-up
On VAV units equipped with heat, if the zone
temperature falls below the daytime warm-up initiate
temperature during the occupied mode, the system will
switch to full airflow. During this mode, the VAV box/
unocc relay will be energized (this is to signal the VAV
boxes to go to 100%). After the VAV box max stroke
time has elapsed (factory set at 6 minutes), the VFD
output will be set to 100%. The airflow will be at 100%
and the heat will be turned on to control to the
occupied heating setpoint.
When the zone temperature reaches the daytime
warm-up termination setpoint, the heat will be turned
off, the relay will be de-energized, releasing the VAV
boxes, the VFD output will go back to duct static
pressure control and the unit will return to discharge
air control. If the occ zone heating setpoint is less than
the DWU terminate setpoint, the heat will turn off when
the occ zone heat setpoint is reached, but it will stay in
DWU mode and cycle the heat to maintain setpoint.
Содержание IntelliPak 2 Series
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