20
SPACE HEATING/COOLING AND DHW
(9) Check Water Volume:
The unit has a built-in 8L expansion vessel, and default
initial pressure is 1 bar. To ensure the unit works
normally, the initial pressure of expansion vessel should
be adjusted according to the circulated water volume.
Use water volume checklist below to decide whether
initial pressure of expansion vessel needs to be
adjusted.
of water in installation system is below the allowed
maximum water volume.
highest point of water circulation and the unit. If the unit
is mounted at the highest point, above all water pipes,
the installation height is deemed to be 0 m.
Calculate initial pressure of expansion vessel. Decide
initial pressure (Pg) according to the maximum
The process of calculating allowed maximum water
volume in whole circulation is:
- Calculate maximum water volume corresponding to
initial pressure Pg by using maximum water volume
curve as shown below.
-
circulation is smaller than above value. Otherwise,
the expansion vessel in the unit is smaller for
system.
0.3 bar is the minimum initial pressure and 1.5 bar is the
maximum initial pressure of expansion vessel set outside the
factory.
When initial pressure in expansion vessel is set as 0.3 bar
at minimum, the water quantity required by system is higher
than the limit value, it may be considered replacing expansion
vessel with bigger volume.
Pg=H/10+0.3
Unit: H (m), Pg (bar)
Water Volume Checklist
Safety Valve
(3 bar)
Installation
height
Water Volume
>220L
No need to adjust initial pressure of expansion
vessel
Things need to do :
Must reduce initial pressure.
Calculate it based on the section “Check
water volume”. Ensure water volume is lower
than allowed maximum water volume (using
>7m
Things need to do :
Must increase initial pressure.
Calculate it based on the section “Check
water volume”. Ensure water volume is lower
than allowed maximum water volume (using
The expansion vessel is too small to install.
(It needs proper expansion vessel or use
safety valve with high activated pressure that
is supplied from local place)
Maximum Water Volume Curve Graph
0.3
0.8
1.3
1.8
2.3
2.8
Initial Pressure (bar)
0 50 100 150 200 250 300 350
Maximum Water Volume(L)
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