7 - STANDARD CONTROL OPERATIONS AND OPTIONS
7.4 Water pump control
The unit can control one water exchanger pump which can be
either a fixed speed pump or a variable speed pump.
The pump can be factory-installed (“internal pump”) or it can be
supplied by the customer (“external pump”).
Pump control logic Internal pump
External pump
Constant speed control
yes
-
Variable speed control
yes
yes
The pump is normally turned on when the unit is running in Heating
mode. The pump control method may vary depending on the
type of the pump (internal or external) and the pump control logic
set by service technicians. When the unit is “Off”, the pump is
stopped; however, the pump can be started in particular operating
conditions when freeze protection of the heat exchanger is active
(see section 7.4.3).
7.4.1 Constant speed control
Fixed speed pump can be controlled through the “Pump 1 Output”
parameter in the Outputs menu. Fixed speed pump control
applies only to internal pumps.
7.4.2 Variable speed control
The water flow is controlled based on Delta T (differential
temperature) on the water exchanger; however, the control logic
may differ depending on the type of the pump (internal/external).
Variable speed control
Internal pump
External pump
LEN drive
yes
-
0-10V drive: Step control
-
yes
0-10V drive: PID control
optional
yes
Internal pump control
The speed of the internal pump may vary depending on the current
unit capacity and service configuration. For example, in defrost
mode higher pump speed equals better efficiency; therefore,
during defrost the pump speed will be set to the maximum speed
that is allowed. At the same time, when the unit is running, but
there is no heating demand, the pump speed will be low.
Under normal operating conditions, the unit’s nominal water flow
should correspond to the minimum pump speed.
Depending on factory installation, the internal pump can be
controlled either through the standard LEN drive or the optional
0-10V drive. The internal pump control can be set only by
service technicians.
When controlled through the LEN drive:
•
The status of the internal pump is displayed in the Pump
Status menu under “Drive pump status”.
•
“External Pump Output” (PUMP_EXT, Pump Status menu)
and “External Pump Output” (PUMP_EXT, Outputs menu)
will be set to “0”.
When controlled through the 0-10V drive:
• The drive output is controlled through 0-10V output,
i.e. “External Pump Output” (PUMP_EXT, Outputs menu).
•
“External Pump Output” (PUMP_EXT, Pump Status menu)
displays its value in %.
•
The output is controlled by a PID to satisfy the Water Delta T
Setpoint defined by service technicians. When the unit is
ready, the pump speed is set to pump saving speed
(minimum pump speed). When the unit is running, water
pump speed is clamped between the minimum and
maximum pump speed.
External (customer) pump control
The control allows for managing the external 0-10V pump via
the 0-10V Pump Config menu (FLOWCONF).
When controlled through the 0-10V drive:
•
The pump is controlled through 0-10V output, i.e. “External
Pump Output” (PUMP_EXT, Outputs menu).
•
“External Pump Output” (PUMP_EXT, Pump Status menu)
displays its value in %.
The customer pump can be controlled by:
•
Step control logic:
• a step value is added to the output each time the
“Reschedule timer” has elapsed and
Delta T > Water Delta T Setpoint [dt_stp] + Deadband
• a step value is removed from the output each time the
“Reschedule timer” has elapsed and
Delta T < Water Delta T Setpoint [dt_stp] - Deadband
•
PID control logic:
The output is controlled by a PID to
satisfy Water Delta T Setpoint.
To set 0-10V pump control method
1. Navigate to the Configuration menu.
2. Select
0-10V Pump Config
(FLOWCONF).
3. Set the pump control logic [logictyp].
Logic: 0=No,1=STEP,2=PID [logictyp]
0 = no (no external pump)
1 = Step control logic
2 = PID control logic
7.4.3 Pump protection (pump anti-stick function)
The control provides a means to automatically start the pump
each day at 14:00 for 2 seconds when the unit is off.
Starting the pump periodically for a few seconds extends the
lifetime of the pump bearings and the tightness of the pump seal.
To set pump automatic rotation delay
1. Navigate to the Configuration menu.
2. Select
Pump Configuration
(PUMPCONF).
3. Set
Pump Sticking Protection
[pump_per] to “yes”.
Pump Sticking Protection [pump_per]
no/yes
yes
EN - 21 AQUACIAT
CALEO
