When using the pump-down function with the Optyma™ controller there are several aspects of the application you must take into consideration when setting up and wiring in the controller. In this article we will look at the differences in setting up the Single phase and 3-phase 4hp & 7.5hp controllers.
Pump-Down with the single phase Optyma™ Controller
The first thing to consider when using the single phase Optyma™ controller for pump down is whether the compressor is connected directly to the output of the Optyma™ controller or if the power to the compressor is already on the condensing unit (contactor or relay).
Where the Optyma™ controller is directly connected to the compressor, of the condensing unit, the compressor is powered from the internal relay of the controller, therefore, it is necessary to set the programming variable AU to activate the pump down function. To set the AU variable you will need to access the Level 2 programming (Installer level), this is done by selecting the UP (^) and DOWN (v) keys and the LIGHT key simultaneously for a few seconds.
When the first programming variable appears the system automatically goes to stand-by.
1. To select the required variable to be modifi ed press the UP (^) and DOWN (v) keys. When the variable is selected it is possible to:
2. View the setting by using the SET key.
3. Modify the setting by holding the SET key and pressing the (^) or (v) key.
4. When configuration settings have been completed you can exit the menu by pressing the (^) and (v) keys simultaneously and keep them pressed until the room temperature reappears.
5. Changes are saved automatically when you exit the configuration menu.
6. Press the STAND-BY key to enable electronic control.
As previously stated the variable for selecting pump-down is AU which must have
a value of 4 as shown in the list below:
With AU = 4 the pump-down function is activated (for version with AUX/Alarm relay only). Connect the pump-down pressostat on the digital input INP-1. The compressor is directly controlled by this pressostat.
Connect the evaporator solenoid valve on the AUX relay. The solenoid is controlled
directly by the thermostat.
In the case where the power to the compressor is already on the condensing unit, which is fitted with a contactor and pump-down pressostat that are directly controlling the compressor,
then no pressostat should be fitted to the Optyma™ controller and the AU variable must not be set to 4.
With this set-up the solenoid valve should be connected to the compressor output (14-15).
Pump-down with 3-phase Optyma™ controller
Select the PUMP-DOWN function mode for the compressor working on X1 terminal block, change the selection connection as indicated in the wiring diagrams.
The AU parameter must never be set at 4, as the PUMP-DOWN function is made electro-mechanically inside the panel.