Mitsubishi Electric CAHV-R450YA-HPB Service Manual page 115

[ VII Control ]
Cooling/heating Circuit Control and General Function of System Equipment
-13- Water-temperature control
Water temperature can be controlled in the following three ways. Select one that works best.
Outlet-water-temperature-based control
Inlet-water-temperature-based control
Water temperature control based on the
external water temperature reading
Outlet-water-temperature-based control
Inlet-water-temperature-based control
Water temperature control based on the
external water temperature reading
*1 When dip switch SW5-8 is set to ON, the ON/OFF operation of the units is controlled based on the external water
temperature sensor reading.
How the operating frequency of the compressor is controlled depends on the SW6-3 setting (outlet-/inlet-based control
option).
(Sub units will be controlled based on the water-temperature control method that has been selected for the Main unit.)
1. When the units are restarted after stopping for under a condition other than Thermo-OFF
Conditions for the units to stop other than the Thermo-OFF condition
The control option was changed from built-in thermistor reading based control to the external thermistor reading based
control.
Pump interlock is off.
When one of the units in a set is forced to stop
When the Capacity priority/Cop priority setting was changed.
When the units were stopped under the following conditions:
1. Tmax has reached 65ºC (when the outside temperature ≤ -25ºC) or
2. Tmax has reached 70ºC (when the outside temperature > -20ºC.
DIFF1 = 2 ºC (Initial setting): "1015" Digitally set value
DIFF2 = 2 ºC (Initial setting): "1016" Digitally set value
Tmax (Outside temperature
Single/Multiple system
Individual system
Multiple system
HWE22020
Switch
SW6-3
SW5-8
SW6-3
OFF
ON
Arbitrary
≤
-25 ºC: 65ºC, Outside temperature > -20 ºC : 70ºC)
sensor
Built-in thermistor
Representative water
temperature
Representative water
temperature
Factory setting
OFF
-
OFF
SW5-8
OFF
OFF
*1
ON
Control method
Outlet water temperatures
< (Preset water temperature - DIFF1ºC)
Inlet-water-tempera-
AND
ture-based control
Inlet water temperatures
< (Preset water temperature - DIFF1ºC)
Outlet water temperatures
< (Preset water temperature - DIFF1ºC)
AND
Outlet-water-tem-
Inlet water temperatures
perature-based con-
< (Preset water temperature - DIFF1ºC)
trol
AND
Average outlet water temperature
≤ (Preset water temperature+ DIFF2ºC)
Representative water Representative water temperature
temperature < (Preset water temperature - DIFF1ºC)
Representative water temperature
< (Preset water temperature - DIFF2/2)
AND
Representative water
The number of units to run an optimal opera-
temperature
tion will be determined by the main unit.
(The unit with the least amount of cumulative
operation hours will go into operation first.)
- 106 -
Thermo-ON conditions
GB