Backup Control; Water Pump Protection Control - Mitsubishi Electric CMB-WP1016V-GA1 Service Handbook

[ VI Control ]

Backup control

-9- Backup control
The following backup control is started on the HBC as necessary.
(1) Backup mode for plate heat exchanger protection
The following control is performed depending on the outlet pipe temperature of the plate heat exchanger for freeze-up pro-
tection.
[Cooling-main/Heating-main operation]
1) Outdoor unit (Heat source unit)
Cooling-main operation: Continued; Heating-main operation: Continued
2) HBC controller
Outdoor unit Operation
(Heat source mode
unit)
HBC controller 21S4Ma
21S4Mb
LEV1
LEV2
LEV3
SVM1
PUMP1
PUMP2
VB3a~p
(2) Heating water temperature backup mode
When the heating operation can be continued without receiving heat from the refrigerant due to water temperature rise during
heating operation (the outlet pipe temperature of the plate heat exchanger is 50ºC or above), the outdoor unit goes into the
Thermo-OFF mode, and the heating operation is performed only by circulating the hot water by the water pump. When the
water temperature decreases to a certain level (the outlet temperature of the plate heat exchanger is 45ºC or below), the out-
door unit starts up.

Water pump protection control

-10- Water pump protection control
When the circuit is clogged or air enters the water circuit, the protection control starts on the HBC controller to protect the
water pump and the system is stopped depending on the situation.
(1) When the internal temperature of the water pump increases
When the detection temperature of the water pump outlet pipe is above a certain level, the water pump is stopped to protect
it from the heat.
(2) When the revolutions of the water pump increases
When the revolutions of the water pump is above a certain level (The value changes depending on the specified voltage.),
the water pump is stopped to reduce the risk of air infiltration and water leaks.
HWE1410A
Cooling-main/Heating-main
Continues the current operation
Heating side: open (de-energized)
Cooling side: open (de-energized)
Maintains the opening that was used in the
previous operation mode
41 pulses: fully closed
3000 pulses: fully open
Closed
Continues the heating operation
Continues the cooling operation
The opening depending on the indoor unit
operation mode
- 78 -
Control mode
Cooling-only
Cooling-only Thermo-OFF
Cooling side: open (energized)
Cooling side: open (de-energized)
Opening during Cooling-only Thermo-OFF
Opening during Cooling-only Thermo-OFF
Opening during Cooling-only Thermo-OFF
Open
Continues the cooling-only operation
Continues the cooling-only operation
The opening depending on the indoor unit
operation mode
GB