Honeywell SDC Service Manual page 199

SDC / DHC Hydraulic Components
Solar tank maximum If the temperature in the solar tank (hot-water tank or buffer tank)
temperature limit exceeds the set value, an active forced switch-on of the solar
loading pump (see description for collector maximum temperature
limit) is interrupted. This forced switch-on is enabled again as
soon as the solar tank temperature falls more than 10 K below its
set limit.
Solar control mode This function defines the solar loading mode.
Solar priority mode (disabling of heat generator)
During solar loading, all demand for the heat generator is
suppressed.
Solar parallel operation
During solar loading, demand for the heat generator is permitted.
Solar priority mode - hot water (setpoint control)
During solar loading, demand for the hot-water control at the heat
generator is suppressed.
Solar priority mode - buffer (setpoint control):
During solar loading, demand for the buffer control at the heat
generator is suppressed.
Heat generator cycle
Heat generator cycle disable (only with solar control mode =
disable priority mode)
The cycle disable serves to prevent frequent switching between
solar loading and loading by the heat generator. After a solar
loading pump switch-off, the set time has to pass before the solar
buffer tank can be loaded again by the heat generator (boiler).
EN2H-0221GE51 R0812 199