Sunhome Tech SR1568, Operation Manual

Page: 64 / 87

Operation manual of solar controller SR1568
Page 63 of 87
Different cooling functions can be activated: system cooling, tank cooling and external
radiator heat transfer.

OSYC System cooling
The system cooling function aims to keep the solar system operational for a longer time. The
function overrides the maximum tank temperature to provide thermal relief of the collector
field and the heat transfer fluid on hot days. If the tank temperature is higher than the
adjusted maximum tank temperature and the switch-on temperature difference DTCO is
reached, the solar pump remains switched on or will be switched on. Solar loading is
continued until either the temperature difference falls below the adjusted value DTCF or the
collector emergency shutdown temperature CEM is reached.
Note: This function will only be available when the collector cooling function, external
radiator heat transfer functions are not activated.

OSTC Tank cooling
When the tank cooling function is activated, the controller aims to cool down the tank during
the night in order to prepare it for solar loading on the following day. If the adjusted maximum
tank temperature SMAX1, SMAX2 is exceeded and the collector temperature falls below the
tank temperature and down to the switch on temperature difference DTCO of this cooling
function, then system will be activated in order to cool down the tank by releasing the energy
through the collector.
Note: if tank temperature reaches to 95 oC, all cooling functions will be locked.
Hysteresis switch on temperature difference is 5K.

OHDP external radiator heat transfer
External radiator heat transfer function can be used to direct excess heat generated by
strong solar irradiation to an external heat exchanger (e. g. fan coil) in order to keep the
collector temperature within the operating range.
For this function, an extra output should be added.
External radiator heat transfer function can either control an additional pump or valve
( OTPUM ON = pump logic, OTPUM OFF = valve logic).