Supplementary Information (Pump Down) - Mitsubishi Electric EHST20-Serie Installationshandbuch

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Supplementary information
refrigerant recovery (pump down) for split systems only
For split system the following procedures should be followed to recover system refrigerant:
note) Pump down operation can not be activated by switching the pump down switch (SWP) or test run switch on the outdoor unit PCB.
ensure both the outdoor unit and the indoor unit are in emergency mode before carrying out the following.
For pump down operation in split systems both the indoor and the outdoor unit must be in emergency mode.
Please see the following instructions on how to activate emergency mode.
Before carrying out the pump down, ensure the water pump is functioning correctly and l9 error code is not displayed on the main controller.
If there is insufficient water circulation, the circuit may freeze causing damage to the plate HEX.
if there is a fault with the pump or l9 error code is displayed on the main controller, do not attempt pump down operation.
in this case a refrigerant recovery machine must be used.
. Isolate outdoor unit from power supply by switching OFF relevant circuit breaker.
If the indoor unit is powered independently to the outdoor unit, ensure that both units are isolated from the power supply.
2. Fully close the stop valve on the refrigerant (liquid) pipe and attach the pressure gauge to the port on the low pressure side of the compressor refrigerant pipe work.
Change the position of the connector CN3 to ON and change DipSW4-2 to OFF on the outdoor unit PCB.
Change the DipSW4-5 on the indoor unit to ON.
3. Switch ON power to the outdoor unit.
If the indoor unit is powered independently, switch on power to the indoor unit first, then switch on power to the outdoor unit.
Outdoor and indoor unit will start operating in emergency mode.
note) if the outdoor unit is operated whilst the indoor unit is switched off, this could cause serious damage to the plate HeX.
Always ensure the indoor unit power supply is On and water pump is operating before switching On power to the outdoor unit.
After reconnecting power supply, ensure the water pump is operating correctly.
if the water pump is not operating normally, then this could cause the water circuit to freeze damaging the plate HeX.
4. When the pressure gauge reads close to 0MPa (G), close the valve on the refrigerant (gas) pipe and then switch power to outdoor unit OFF.
If the indoor unit is powered independently ensure power supply for unit is OFF.
note) it is important that after closing the valve on the refrigerant (gas) pipe the power supply is quickly switched OFF.
if the system is running at a pressure of 0MPa (G) or lower, it may cause damage to the compressor.
5. After completing the pump down operation, return the position of the connector CN3 on the outdoor unit PCB to OFF.
Change the Dip SW4-5 on the indoor unit to OFF.
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