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10 Function of the check valves [Expert]
Within their application range, the check valves of this station prevent unwanted gravity
circulation. The functioning 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 siphons ("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 tank is larger, the difference in density of
the solar fluid will be so large that the check valves are pushed open.
28
Circulation
Temperature difference storage tank/collector in K
997xx3xx-mub-en – V01
10 Function of the check valves [Expert]
Solar fluid
2020/08
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