Honeywell SDC Service Manual page 190

Hydraulic Components
NOTE
Control mode
190
This function limits the temperature in the water heater upward
based on the set value. The desired water heater daytime
temperature to be set on the user level is limited by this set value.
ATTENTION
Hot water maximum temperature limit is a function protecting
the tank and terminates hot water loading. If overshooting
occurs, the tank loading pump switches off immediately. In
this case it cannot be ensured that the set extended running
time is adhered to.
If a hot-water circuit thermostat is used instead of an electronic
sensor, the hot water maximum temperature setting (plus the
specified temperature shift during loading) is forwarded to the
heat generator.
With this function it is set how the rest of the heating system
reacts to heat demand from the hot-water tank. There are 5
different setting options.
Parallel operation
During hot-water circuit loading, the heating circuits remain
operative.
Priority mode
During hot-water loading, the heating circuits are put out of
operation. They are restarted as soon as the hot-water circuit
loading pump extended running time is over.
If the hot-water setpoint temperature is not reached after 4 hours,
a fault message is indicated on the display.
Conditional priority
If the temperature of the heat generator has exceeded the loading
temperature for the hot-water tank, mixed heating circuits are
enabled. Non-mixed heating circuits (DHCP) remain disabled
during hot-water circuit loading. The heating circuits are enabled
according to the following criteria:
Enabling the heating circuits:
Heat generator actual temperature > hot-water setpoint
temperature + hot-water switching differential/2 + 10 K
SDC / DHC
EN2H-0221GE51 R0812