M thermal Mono
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4 Normal Operation Control
4.1 Component Control during Normal Operation
Table 3-4.1: Component control during heating and domestic hot water operations
Component
Wiring diagram label
18/22/26/30kW
Control functions and states
Inverter compressor
COMP
Controlled according to load requirement from hydronic
system
DC fan motor
FAN_UP / FAN_DOWN
Controlled according to outdoor heat exchanger pipe
temperature, ambient temperature and compressor speed
Electronic expansion valve
EEV1
Controlled according to discharge temperature, discharge
superheat, suction superheat and compressor speed
Four-way valve
ST
On
Table 3-4.2: Component control during cooling operation
Component
Wiring diagram label
18/22/26/30kW
Control functions and states
Inverter compressor
COMP
Controlled according to load requirement from hydronic
system
DC fan motor
FAN_UP / FAN_DOWN
Controlled according to outdoor heat exchanger pipe
temperature, ambient temperature and compressor speed
Electronic expansion valve
EEV1
Controlled according to discharge temperature, discharge
superheat, suction superheat and compressor speed
Four-way valve
ST
Off
4.2 Compressor Output Control
The compressor rotation speed is controlled according to the load requirement. Before compressor startup, the M thermal
Mono outdoor unit determines the compressor target speed according to outdoor ambient temperature and discharge
temperature and then runs the appropriate compressor startup program. Refer to Part 3, 3.2 Compressor Startup
Program . Once the startup program is complete, the compressor runs at the target rotation speed.
During operation the compressor speed is controlled according to the setting and actual water temperature, the
refrigerant system pressure, refrigerant temperature and ambient temperature.
4.3 Compressor Speed Control
The running speed of six-pole compressors (used on all models) in rotations per second (rps) is one third of the frequency
(in Hz) of the electrical input to the compressor motor. The frequency of the electrical input to the compressor motors can
be altered at a rate of 1Hz per second.
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