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System Operation And Troubleshooting - Bosch BOVA Series Installation Instructions Manual

Split system heat pump condensing units up to 18 seer 2-3-4-5 ton capacity
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Installation Instructions

15 System operation and troubleshooting

15.1
Control logic description
The variable speed system adopts the same 24VAC control as any
conventional Heat Pump.
The compressor's speed is controlled based on coil pressures monitored
by pressure transducer. To insure stable and adequate capacity, the
compressor speed will modulate relative to evaporator pressure during
cooling operation and relative to condensing pressure during heating
operation. The target pressure can auto-matically adjust based on
compressor operation so optimal capacity can be achieved. Target pressure
can manually be adjusted (SW4) to achieve improved dehumidification and
capacity demands.
ON
1
2
3
4
OFF
Figure 40
Switch
SW4-1
SW4-2
ON
SW4-3
OFF
ON
SW4-4
OFF
Table 8
15.2
Sensors (thermistors/pressure transducer)
t3 = Outdoor Coil Temperature (Table 1)
High/Low temperature protection
Outdoor fan control (cooling mode)
Defrost control (heating mode)
Ambient Temperature forecast
T4 = Ambient Temperature (Table 1)
Operating condition permission
Defrosting condition permission
Outdoor fan control (heating mode)
T5 = Compressor Discharge Temperature (Table 2)
High/Low temperature protection
Electronic Expansion Valve (EEV) control (ODU)
Bosch Thermotechnology Corp. | 12.2016
Description
Not used
Not used
Adaptive capacity output disable
Adaptive capacity output enable
Accelerated cooling/heating
Normally cooling/heating
TF = IPM Radiator Temperature) (Table 2)
Inverter High Temperature Protection
Pressure transducer (Table 3)
Operating speed control
Electronic Expansion Valve (EEV) control (ODU)
High pressure protection (heating mode)
Low pressure protection (cooling mode)
15.3
Defrost description
The Demand Defrost Control (DDC) monitors the ODU coil temperature
using thermistor (T3). A second thermistor (T4) monitors outdoor ambient
temperature. Based on these parameters, as well as accumulative run time
and high pressure, the DDC calculates proper initiation of defrost.
The following three conditions are required to enter defrost:
1.
Outdoor coil temperature T3 < 34°F and a corresponding minimum
outdoor ambient temperature is met.
2.
After "Minimum Run Time" (MRT) is achieved. MRT is based on outdoor
ambient temperature (T4), for example:
MRT is 4 hours when: T4 < 23°F
MRT is 2 hours when: 23°F ≤ T4 < 42°F
3.
After the high pressure saturation temperature drops below 82°F for 20
minutes.
Defrost will terminate once outdoor coil temperature (T3) reaches 64°F for
a period of 1 minute or defrost time has exceeded 8 minutes.
Defrost Termination Settings (SW5) offers different defrost termination
options for enhanced defrost for different geographical &/or outdoor
conditions.
SW5
ON
1
2
OFF
Figure 41
Defrosting choice
SW5-1
Operating time is
ON
reduced by 10%
OFF
Normal
Remarks
Enter defrost
Table 8
Bosch IDS BOVA | 21
SW5-2
Remarks
Defrosting extended
for 60 seconds
Normal
Default
Quit defrost
Data subject to change

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This manual is also suitable for:

Bova-36Bova-60