Panasonic WH-UD07FE5 - Hydraulic Decoupling for Standard Pumps and High-Efficiency Pumps; Without Differential Pressure Control; Hydraulic Decoupling for High-Efficiency Pumps with Differential Pressure Control

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Aquarea air / water heat pump – design handbook 07 / 2014
Project Design
Hydraulics
Hydraulic integration
In individual cases, one or more water circulation pumps may be needed
for the respective heating circuits in addition to the device-internal water
circulation pump. If this is the case, the heat pump circuit and the heat
emitter circuit must be hydraulically decoupled via a buffer tank or a
hydraulic switch (low loss header). When integrating without hydraulic
decoupling, it must be ensured that the minimum circulation specied for
the respective heat pump (see technical data) is maintained at all times.
Automatic mixers or thermostatic valves can restrict the hot water circu-
lation to such an extent that the ow falls below the minimum circulation.
To prevent this, Panasonic recommends always combining heat transfer
systems without hydraulic decoupling with an auto-bypass valve
between the heating supply ow and return ow. The auto-bypass
valve must be designed for the nominal volume circulation of the
respective heat pump.
In contrast to standard pumps, high-efciency pumps with differential
pressure control have an independent controller. If the resistance in the
heating circuit increases, e.g. because thermostatic valves close, the
high efciency pump detects an increased differential pressure and auto-
matically reduces the speed and volume ow. That ensures that the
water circulation pump does not consume electricity unnecessarily.
The pump supplies the heat transfer system with a lower volume ow
until the valves re-open and the speed increases automatically due to
the decreasing differential pressure until the nominal volume ow or
the target differential pressure is reached.
The high-efciency pumps with differential pressure control used in
the Aquarea heat pumps have two control modes that can be set at
the pump.
Hydraulic decoupling
for standard pumps and
high-efciency pumps
without differential
pressure control
Hydraulic decoupling
for high-efciency pumps
with differential pressure
control
Q [l / min]
H [kPa]
max
Δ p-c
n
max
Q [l / min]
max
Δ p-v
n
max
H [kPa]
Δ p-v – variable differential pressure:
The electronic system changes the differential pressure target to be
maintained by the pump (congurable between levels 2 to 6), whereby
the differential pressure decreases simultaneously with the volume ow
to max. half of the differential pressure target.
Δ p-c – constant differential pressure:
The electronic system holds the differential pressure target to be
maintained by the pump at the value set (level 1 to 7) up to the
maximum point. Panasonic recommends this type of control.