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Technical manual
The expansion volume of the system Vep can be calculated using Equation 7.
β
=
⋅
V
V
ep
sys
Where:
V
ep
V
sys
β
The pressure relief valve pressure p
ever, to allow for some tolerance it is recommended to calculate the pressure relief
valve pressure p
rv
=
⋅
1 ( −
p
p
0
) 1 .
rv
op
Where:
p
rv
p
op
The last parameter to be calculated for use in Equation 5 is the cold fill pressure p
the system. The cold fill pressure p
thermal system and the required pressure in the highest system point p
tion of the static height h
The pressure in the highest system point p
cold fill pressure p
bar
=
+
⋅
p
p
0
1 .
pc
min
m
Where:
p
pc
p
min
h
stat
Equation 9 concludes the calculation of parameters required for Equation 4 to calculate
the expansion vessel volume V
membrane pre-charge pressure p
[l]
system expansion volume
[l]
total system volume
[-]
heat transfer medium expansion coefficient (0.00085)
in accordance with Equation 8.
[bar]
relief valve pressure
[l]
opening pressure of relief valve (6 bar)
is depicted in Figure 33.
stat
Figure 33 – Definition of static height of solar system
can therefore be calculated as shown in Equation 9.
pc
h
stat
[bar]
cold fill pressure
[bar]
pressure in highest system point
[m]
static height of system
. To be able to commission the expansion vessel, the
EV
mp
can as first approximation be used as 6 bar. How-
rv
depends on the static height h
pc
should be between 1 and 1.5 bar. The
min
has to be calculated as shown in Equation 10.
SOLAR
stat
min
h
stat
ST0133 – A 02/09
[7]
[8]
of
pc
of the solar
. The defini-
[9]
Page 33 of 72
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