Orion System VCM Controller - Manual (Page 34)

Technical Guide
VCM Controller 34
Inputs & Outputs
VCM Controller
AIN1 - Space Temperature Sensor Input
If you want to generate Occupied or Unoccupied Heating and Cooling
demands based on Space Temperature, select this Sensor for the HVAC
Mode enable. The Space Temperature Sensor can be used for Night
Setback control regardless of the HVAC Mode Sensor selected. If the
Space Temperature Sensor used is equipped with the optional Push-
button Override Feature, this input will detect user overrides from Un-
occupied back to Occupied operation for a user adjustable amount of
time. This Sensor is not required for Cooling Only HVAC units config-
ured for Supply Air Temperature control as the HVAC Mode Enable
Sensor, unless Night Setback operation is required. The Space Tem-
perature can also be configured to reset the Supply Air Temperature
Setpoint. The Space Temperature Sensor is the only Sensor that can be
used for Night Setback operation during the Unoccupied Mode.
AIN2 - Supply Air Temperature Sensor Input
The Supply Air Temperature Sensor is the default HVAC Mode Enable
Sensor. For typical VAV units that are Cooling Only with Morning Warm-
up, this Sensor should be configured as the HVAC Mode Enable Sen-
sor. Heating will only occur during Morning Warm-up. After Morning
Warm-up expires, the Supply Air Temperature will be maintained at the
Supply Air Temperature Cooling Setpoint. The HVAC unit must al-
ways have a Supply Air Temperature Sensor installed.
AIN3 - Return Air Temperature Sensor Input
If you want to generate occupied Heating and Cooling demands based
on Return Air Temperature, select this Sensor as the HVAC Mode En-
able Sensor. The Return Air Temperature Sensor is also used to initiate
or cancel the Morning Warm-up Period. This temperature must be at
least 5°F above the Outdoor Air Temperature to allow Economizer-
Cooling operation.
AIN4 - Outdoor Air Temperature Sensor Input
The Outdoor Air Temperature is used to lockout Heating or Cooling to
conserve energy at whatever temperature the user deems appropriate
for each Mode of operation. The Outdoor Air Temperature Sensor can
also be used to provide Low Ambient Temperature Protection in the
building. If the Outdoor Air Temperature is below the Low Ambient
Temperature Setpoint, the Preheat Relay Output will be maintained dur-
ing Occupied operation and will not be allowed to stage off unless the
Supply Fan is turned off. When using 100% (MUA Units) Outdoor Air
applications, the Outdoor Air Temperature Sensor should be config-
ured as the HVAC Mode Enable Sensor. The Outdoor Air Temperature
Sensor is also used in combination with the Outdoor Air Humidity Sen-
sor for Dewpoint calculations.
AIN5 – Suction Pressure Sensor Input
A Suction Pressure Sensor can be connected to this input. This Sensor
is required when using Dehumidification with DX Cooling units. The
VCM controller converts the Suction Pressure reading to Suction Tem-
perature. This calculated Evaporator Coil Temperature, is considered to
be the Saturation Vapor Pressure of the refrigerant leaving the evapora-
tor coil. In most cases, the Supply Air Temperature leaving the Evapo-
rator coil will be 10°F to 15°F higher than the calculated Evaporator
Coil Temperature.
Note: All temperature Sensors must be Thermistor Type III
which provide 77.0°F @ 10 K Ohms Resistance.
AIN6 - Duct Static Pressure Sensor Input
This special phone jack style input connection accepts a Duct Static
Pressure Sensor input modular cable. The Duct Static Pressure Sensor
reading is used to determine current Duct Static Pressure. This Static
Pressure reading is used to control the output signal supplied to the
Supply Fan VFD or Zoning Bypass Damper Actuator. If you have con-
figured the HVAC unit for Constant Volume operation, this Sensor is
optional. If it is installed on a Constant Volume unit, it will not affect
operation, it will be used as a status only reading.
AIN7 – Space Temp. Sensor Slide Adjust or
Remote SAT Reset Signal Input
AIN 7 on the VCM controller is a dual purpose input. It can be used for
the Space Sensor Slide Adjust option or for connection of the Remote
Supply Air Setpoint Reset Signal option. Only one or the other can be
used not both.
Space Temperature Sensor Slide Adjust
If the Space Temperature Sensor being used has the optional Slide Ad-
just feature, its AUX output is connected to this input. The Slide Adjust
control is used to vary the HVAC Mode Heating and Cooling Setpoints
by a user configured maximum amount. The Slide Adjustment adjusts
whichever Temperature Sensor that has been configured as the HVAC
Mode Enable Sensor even if that Sensor is not the installed Space Tem-
perature Sensor.
If Space Temperature is configured as the SAT/Reset Source, the Slide
Adjustment adjusts both the HVAC Mode Enable Heating and Cooling
setpoints and the SAT/Reset Source Heating and Cooling setpoints si-
multaneously by a user configurable maximum amount.
Remote Supply Air Temperature Reset Signal
When a 0-5 VDC Remote Supply Air Temperature Reset Signal is to be
used, the controller must be configured for it and the Room Sensor
Slide Offset setpoint must be set to zero for this option. If the slide
offset is not set to zero, the Supply Air Temperature Reset will not func-
tion.
The Remote Supply Air Temperature Reset signal must be configured
so its setpoint will be at the coldest Supply Air Temperature at 0 VDC
and its setpoint will be at the warmest Supply Air Temperature at 5
VDC.
If a 0-10 VDC reset signal is used, a resistor network will need to be
installed on AIN 7. See the VCM wiring diagram for details.
AOUT1 - Economizer Control Signal
This voltage signal (2-10 VDC) is used to position the Outdoor Air
Damper during Economizer Control. It is also used to maintain the
Outdoor Air Damper at its Minimum Position during the Occupied Mode
when the Outdoor Air Temperature and/or Outdoor Humidity is not
suitable for Economizer Cooling purposes.