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1. Group of modules control
The module controller provides group control over multiple modules.
(1) Controlling the number of modules by detecting the flow rate
The module controller detects the flow rate required by the load side to determine how many modules need to be
operated. It provides rotation control, which prioritizes modules with the shortest cumulative running hours to
balance running hours among all modules. The required flow rate is determined as follows:
[Duplex pump system]
The module controller measures the temperature
balance via the entering and leaving thermistor
sensors for water temperature inside the heat
pump and the thermistor sensors for water
temperature on the supply and return pipes
(external sensors attached to the module
controller). Based on this measurement, the
module controller determines the number of
modules to be operated and their respective flow
rates in such away as to minimize the imbalance
between the estimated load-side flow rate
requirement and the heat pump-side flow rate.
[Single pump system]
The module controller measures the temperature
balance via the entering and leaving thermistor
sensors for water
temperature inside the heat pump
and the thermistor sensors for water temperature on
the supply and return pipes (external sensors
attached to the module controller). Based on this
measurement, the module controller determines the
number of modules to operate and their respective
flow rates in such a way as to make the water flow
close to the estimated load-side flow rate.
※
1 You can perform variable flow rate control even without sensors. You can connect to the MC to perform tasks such as
measuring the amount of heat on the load side.
※
2 If a system has a flow meter, module control based on a direct measurement of the load-side flow rate
can be made
possible by connecting the flow meter output to the module controller. Flow rate measurement using thermistor
sensors for water temperature incur sensing delays and errors: thus in cases where the bypass pipe is narrow or load
fluctuations are fast, the internal pumps may stall, resulting in an abnormality such as a low flow rate error. For this
reason, use of a flow meter is recommended. See the Installation Manual for module control for other types of system
such as those in which: a) a water piping system is associated with multiple USX groups, b) this heat pump is used
together with another model, or c) the system is a constant-flow system.
Control Flow
Control of the number of unit controllers by operating capacity
5 connected modules
N
u
m
ber
of
op
er
ati
n
g u
n
it con
tr
o
lle
rs
[u
ni
ts]
Operating capacity [%]
When
increasing
When
decreasing
Heat so
ur
ce sid
e
flow r
a
te [
L
/m
in.]
Flow control by bypass 0 control
10 connected modules
Load side flow rate [L/min.]
Module controller
Leaving water
temperature
sensor
Entering water
temperature
sensor
Expansion tank
Pressure relief circuit
Free bypass circuit
Heat pump side flow rate > load side flow rate
Heat pump side flow rate < load side flow rate
Air conditioner
Air conditioner
Flow meter
Module controller
Entering water
temperature
sensor
Expansion tank
Air conditioner
Air conditioner
Differential pressure
sensor
Leaving water
temperature sensor
Flow meter
Bypass valve
※
1
※
1
※
1
※
1
