Orion System Two Condenser Head Pressure II Module - Manual (Page 9)

Two Condenser Head Pressure II Module Technical Guide
SEQUENCE OF OPERATION
9
VCM-X Input Commands and Modes of Operation
Input Commands (VCM-X Connection)
Condenser A & B On/Off
Instead of a hard wired input signal to the Condenser Enable input,
the VCM-X Modular Controller, VCM-X WSHP Controller, or SA
Controller communicates to the Module via E-BUS communications.
This signal indicates the compressor(s) are called to run and drives the
condenser A & B On/Off function.
Reversing Valve Enable A & B On/Off
As with the Condenser Signal On/Off function, the VCM-X Modular
Controller, VCM-X WSHP Controller, or SA Controller communicates
to the Module via E-BUS communications and signals that the reversing
valve has been energized and that heating has been enabled.
NOTE: When the term “ON” is used, it means there is either 24
VAC on the appropriate Binary Input or a call-to-run
signal is being received from a VCM-X series or SA
series controller. When the term “OFF” is used, it means
there is either 0 VAC on the appropriate Binary Input or
the call-to-run signal from a VCM-X series or SA series
controller has been removed.
Sensor Reading Routine
The Two Condenser Head Pressure Module is used on units with two
physically separate condenser sections. Up to (2) Head Pressure Sensors
can be monitored in each section. The highest of the two readings in
each section will be used to control the condenser fan(s) in that section.
Air from the condenser fan(s) in each section fl ows through both con-
denser coils. As a result, if you modulate the fan(s) based on the highest
reading, you will have enough air fl ow for both coils.
The highest reading of Head Pressure Sensors 1 & 2 controls Condenser
Fan A. The highest reading of Head Pressure Sensors 3 & 4 controls
Condenser Fan B.
Modes of Operation
OFF Mode
The Head Pressure Control Board is in the OFF Mode when the Con-
denser Input Signals are “OFF.” In this mode, all relays are off, the
Analog Output is 0 VDC, and the PWM Output is 0% Duty Cycle.
Cooling Mode
If the Head Pressure Controller has been confi gured for the Reversing
Valve to be energized in the Cooling Mode and to Fail to the Heat Mode
(Dipswitch 4 is set ON), then the Head Pressure Controller will be in
the Cooling Mode when one or both of the Condenser Signal inputs is
“ON” and the Reversing Valve Enable Signal is “ON”. In this circum-
stance, the Reversing Valve Enable Relay Output(s) will energize for
indication purposes.
If the Head Pressure Controller has been confi gured for the Reversing
Valve to be energized in the Heating Mode and to Fail to the Cool Mode
(Dipswitch 4 is set OFF), then the Head Pressure Controller will be in
the Cooling Mode when one or both of the Condenser Signal inputs is
“ON” and the Reversing Valve Enable Signal is “OFF”.
The Condenser Enable Relays will energize to enable the Condenser
Fans or Water Valves. In a water system, the Water Flow Valve will
start at 75% for 3 minutes. The Condenser Output Signals will then
automatically adjust between 0 and 100% to maintain the desired Head
Pressure Setpoint. The Condenser Output Signals can be a 0-10 VDC,
2-10 VDC or 0-100% PWM signal provided by the appropriate output.
Both outputs mirror each other.
Heating Mode
If the Head Pressure Controller has been confi gured for the Reversing
Valve to be energized in the Cooling Mode and to Fail to the Heat Mode
(Dipswitch 4 is set ON), then the Head Pressure Controller will be in
the Heating Mode when one or both of the Condenser Signal inputs is
“ON” and the Reversing Valve Enable Signal is “OFF”.
If the Head Pressure Controller has been confi gured for the Reversing
Valve to be energized in the Heating Mode and to Fail to the Cool Mode
(Dipswitch 4 is set OFF), then the Head Pressure Controller will be in
the Cooling Mode when one or both of the Condenser Signal inputs is
“ON” and the Reversing Valve Enable Signal is “ON”. In this circum-
stance, the Reversing Valve Enable Relay Output(s) will energize for
indication purposes.
In this mode, the Condenser Output Signals will go to 100% and remain
there until it leaves the Heating Mode.
NOTE: The Reversing Valve Dipswitch 4 setting determines
whether the Reversing Valve Dipswitch 4 Relay is ON
to Heat / OFF to Cool or ON to Cool / OFF to Heat.
NOTE: The Reversing Valve Enable outputs are for indication
only and are not wired to anything.