Honeywell SDC Service Manual page 216

Hydraulic Components
Diverter valve
Test cycle
216
to support heating during periods when less solar power is
available.
To ensure that the solar tank in priority operation (temperature
sensing by the sensor of the solar loading switch-over, usually
hot-water tank) can be loaded, checks are performed at regular
intervals to determine whether sufficient solar power is available
(meaning the solar panel temperature is sufficiently high for
loading and the set switch-over temperature can be reached).
This function allows switching of a diverter valve according to the
load condition of two heat storage tanks (two-point output) so that
solar energy can be used to support heating during periods of low
solar intake.
If the switch-over condition is not fulfilled after a preset time
interval of 30 minutes (meaning the temperature in the first-priority
tank remains below the set switch-over temperature) and if the
loading conditions for the second-priority tank (temperature
sensing by the collector tank/buffer sensor, usually buffer tank for
heating support) are fulfilled, the solar loading pump (SOP) is
temporarily switched off after the time set in the "Solar" menu,
parameter 15. During the switch-off time, the differential between
the collector flow sensor (SPFS) and the sensor for solar loading
switch-over (SLVF) is determined. If the switch-on condition is
fulfilled, the first-priority tank is loaded. If the loading condition is
not fulfilled after the set time, loading is continued into the lower
priority tank as long as the loading conditions are not fulfilled.
These cyclical checks are suspended if the temperature at the
solar loading switch-over sensor plus the switch-on differential
becomes greater or equal the set final switch-off temperature.
Solar loading switch-over operation
Only a setting option if a solar loading pump is set on the
hydraulic level.
SDC / DHC
EN2H-0221GE51 R0812