Check Valve - Cosmo Csus50Stg Montage- Und Betriebsanleitung

S O L A R T R A N S F E R S T A T I O N - 5 0 m
2
2 . 4 C H E C K V A LV E
Within their application range, the check valves of this station prevent unwanted gravity circula-
tion. The functioning of the check valves depends:
on the system height
on the temperature difference between storage tank and collector
on the solar 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 to
prevent gravity circulation. You can install, for example, syphons ("heat traps"), 2-way valves
(zone valves) or additional check valves.
Example:
The station contains two check valves (2 x 19.6 mbars = 39.2 mbars).
You use a mixture of water and 40% strength propylene glyclol as solar fluid.
The installation height between collector and storage tank is 10 m.
Temperature difference between 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.
Do you need to know it exactly?
The density of the solar fluid considerably decreases with increasing temperature. In systems
of high system heights and with large temperature differences, the difference in density causes
gravity circulation. This circulation can result in the storage tank cooling down.
Calculation example: Δp = Δρ * g * h
Collector temperature: 5 °C  Solar fluid density ρ1 = 1042 kg/m³
Storage tank temperature: 67 °C  Solar fluid density ρ2 = 1002.5 kg/m³
Δρ = ρ1 - ρ2 = 39.5 kg/m³
g = 9.81 m/s² (acceleration due to gravity)
Installation height h = 10 m
Δp = 3875 Pa = 38.7 mbars
The two check valves of the station (2 x 19.6 mbars) are sufficient for an installation height of
10 m and a temperature difference of up to 62 K between the collector and the storage tank.
Circulation
5 1
Solar fluid