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8 Function of the check valves [specialist]
Within their application range, the check valves of 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 heat transfer fluid used
The diagram below indicates if the check valves integrated in the station are sufficient for your
installation. If the check valves are not sufficient, additional components must be installed in
order to prevent gravity circulation. Components such as syphons ("heat traps"), 2-way valves
(zone valves) or additional check valves can be installed for this purpose.
Example:
The station is equipped with two check valves (2 x 200 mm wc = 400 mm wc).
You use a mixture of water and 40% of propylene glycol as solar fluid.
The installation height between the collector and the storage tank is 10 m.
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 storage tank is larger, the
difference in density of the solar fluid will be so large that the check valves are pushed open.
26
Circulation
Temperature difference collector/storage tank in K
996091425-mub-en – V04
8 Function of the check valves [specialist]
Solar fluid
2016/05
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