Toshiba HWS-802XWHM3-E - Page 81

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7. HYDRO UNIT INSTALLATION MANUAL
Engineering Data Book
Expression for expansion vessel selection
V: Necessary total tank capacity ( )
: Water expansion coefficient at average hot water temperature
Vs: Total water amount in the system
P1: System pressure at tank setting position (MPaabs.)
(Pipe inner pressure during pump operation before heating device operates = water supply pressure)
P2: Maximum pressure used during operation at tank setting position (MPaabs.)
(= safety valve setting pressure)
* The absolute pressure value (abs.) is obtained by adding the atmospheric pressure (0.1 MPa (1 bar)) to the
gauge pressure.
▼ Tank selection method
Install an external expansion vessel when the capacity of the expansion vessel is insufficient.
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 0.0961
40 0.0078 95 0.0967
45 0.0100
0
2
4
6
8
10
12
14
16
18
0 50 100 150
250200 300
*Hot water temperature 55ºC
▼ Fig. 7-15
Expansion vessel volume( )
Water volume ( )
17-EN