– 17 –
Hydro Unit
Installation Manual
Piping to hot water cylinder (option)
Water supplied to the hot water cylinder is branched by
a motorized 3-way valve (locally procured).
For the specifications of the motorized 3-way valve,
refer to “Control parts specifications” on page 22.
Connect the hot water cylinder to port A (open when
energized) of the valve.
▼
Fig. 7-13
Piping to 2-zone operation
To perform 2-zone temperature control, circulate water
by another pump (locally procured) through a
motorized mixing valve (locally procured) and a buffer
tank (locally procured).
For the specifications of the motorized mixing valve,
Refer to “Control parts specifications” on page 22.
▼
Fig. 7-14
Checking water volume and initial pressure
of expansion vessel
The expansion vessel of the Hydro Unit has a capacity
of 12 liters.
The initial pressure of the expansion vessel is
0.15 MPa (1.5 bar).
The pressure of the safety valve is 0.43 MPa (4.3 bar).
Verify whether the capacity of the expansion vessel is
sufficient using the following expression. If the volume
is insufficient, add the capacity locally.
Expression for expansion vessel selection
V: Necessary total tank capacity ( )
: Water expansion coefficient at each hot water
temperature
Vs: Total water amount in the system
P1: System pressure at tank setting position
(MPaabs.)
= water supply pressure = 0.3 (MPaabs.)
(recommended valve)
P2: Maximum pressure used during operation at tank
setting position (MPaabs.)
= safety valve setting pressure = 0.4 (MPaabs.)
* The absolute pressure value (abs.) is obtained by
adding the atmospheric pressure (0.1 MPa (1 bar))
to the gauge pressure.
▼
Tank selection method
▼
Fig. 7-15
Install an external expansion vessel when the capacity
of the expansion vessel is insufficient.
A
B
AB
to hydro unit
room heating or cooling
to hot water cylinder
Open when de-
energized
Open when energized
A
B
AB
Motorized mixing valve
(locally procured)
from hydro
unit
Buffer tank (locally
procured)
Zone
2
Water pump
(locally procured)
to hydro unit
Water temperature and expansion coefficient
Hot water
temperature
(°C)
Expansion
rate
Hot water
temperature
(°C)
Expansion
rate
0
0.0002
50
0.0121
4
0.0000
55
0.0145
5
0.0000
60
0.0171
10
0.0003
65
0.0198
15
0.0008
70
0.0229
20
0.0017
75
0.0258
25
0.0029
80
0.0292
30
0.0043
85
0.0324
35
0.0050
90
0.0361
40
0.0078
45
0.0100
0
2
4
6
8
10
12
14
16
18
0
50
100
150
250
200
300
*In case the maximum hot water temperature is 60ºC
V: Necessary total tank capacity
(
)
Vs: Total water amount in the system( )
17-EN
Summary of Contents for HWS-1405XWHM3-E
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