Vitosol 100-FM/200-FM Installation, Operating and Service
35
5786 604 - 02
Additional Installation Information
For layout of the expansion tank, see “sample system
layout” on page 32.
The expansion tank can be calculated once the steam
spread has been determined and any heat sinks that may
be used have been taken into consideration.
The required volume is determined by the following
factors:
– Expansion of the heat transfer medium in its liquid state
– Liquid seal
– Expected steam volume, taking account of the static
head of the system
– Pre-charge pressure
V
dev
= (V
col
+ V
dpipe
+ V
e
+ V
fv
)·D
f
V
dev
Nominal volume of the expansion tank in USG (L)
V
col
Liquid content of the collectors in USG (L)
V
dpipe
Content of the pipework subject to steam loads
in L. V
dpipe
is zero, because there is no steam
generation for the Vitosol-FM.
V
e
Increase in the volume of the heat transfer
medium in its liquid state in USG (L)
V
e
= Va ·
β
V
a
System volume (content of the
collectors, the heat exchanger and the
pipework, from page 34).
β
Expansion factor
β
= 0.13 for Viessmann heat transfer
medium from -4 to 248°F (-20 to 120°C)
V
fv
Liquid seal in the expansion tank [4% of the
system volume, min. 0.8 USG (3 L)]
D
f
Pressure factor (pe + 1): (p
e
−
p
o
)
p
e
Max. system pressure at the safety valve
in bar (90% of the safety valve response
pressure)
p
o
System pre-charge pressure
p
o
= 44 psi + 0.45 psi/ft static head
(3 bar + 0.1 bar/m static head)
To determine the system and steam volume in the pipework, the content per ft (m) of pipe must be taken into
consideration.
Copper pipe,
Dim.
type M
in.
(mm)
e
(9.5)
b
(12.7)
c
(19.1)
1
(25.4)
1
a
(31.8)
1
b
(38.1)
Capacity
USG/ft
(L/m)
0.0083
(0.103)
0.013
(0.161)
0.027
(0.335)
0.045
(0.558)
0.068
0.844)
0.095
(1.18)
Corrugated stainless
steel pipe
Dim.
DN 16
0.629 in. (16 mm) I.D.
Capacity
USG/ft
(L/m)
0.02
(0.25)
For the liquid content of the following components see
“System fluid calculator” on page 34.
- Solar piping
– Collectors
– Solar-Divicon and solar pump assembly
– DHW tank and heating water buffer tank
Selection of the expansion tank
The details in the following table are standard values.
They allow quick estimates at the design and calculation
stage. These values must be verified by appropriate
calculations.
Note:
Check the size of the expansion tank on site.
Expansion Tank
Note:
Contact your local Viessmann sales representative
for expansion tank sizing assistance.
