8 Function of the check valves [Expert]
2017/05
99609x4x5-mub-en – V05
29
8
Function of the check valves [Expert]
Within their application range, the check valves in this station prevent unwanted gravity
circulation. The efficiency of the check valves depends on:
the installation height
the temperature difference between the storage tank and the collector
the type of heat transfer medium
In the diagram below you can see whether the check valves integrated in the station are
sufficient. If the check valves are not sufficient, you need to install additional components to
prevent gravity circulation. You can mount components such as syphons ("heat traps"), 2-way
valves (zone valves) or additional check valves.
Example:
The station comprises two check valves (2 x 200 mm wc = 400 mm wc).
You use a mixture of water and 40% of propylene glycol as a solar fluid.
The installation height between the collector and the storage tank is 10 m.
Instal
latio
n hei
gh
t i
n
m
Temperature difference storage tank/collector in K
Result:
The check valves prevent gravity circulation up to a temperature difference of about 62 K. If the
temperature difference between the collector and the tank is larger, the difference in density of
the solar fluid will be so large, that the check valves are pushed open.
Circulation
Solar fluid
