Honeywell SDC Service Manual page 189

SDC / DHC
Hot-water circuit - night-
Legionella protection
NOTE
Temperature
measurement
NOTE
Maximum hot water
temperature
EN2H-0221GE51 R0812
Hot-water economy temperature is the setpoint for the hot-water
time
tank between the active operating mode times in automatic mode.
If a hot-water thermostat is used to determine the water heater
temperature, the parameter for the setting of the economy
temperature is skipped.
In order to kill Legionella germs in the tank, a Legionella
protection function can be activated. Activation is carried out in
the "Hot Water" menu, parameter 2.
To ensure full destruction of germs, the set value of the Legionella
protection temperature must be at least 65°C.
The setting is carried out with two parameters. The weekday for
Legionella protection can be selected by the user with a freely
accessible parameter. With parameters 03 and 04, the time and
temperature can be set by the heating technician.
The thermostat which controls the max. limit of the heat generator
must be set to a higher setpoint than the setpoint of the legionella
temperature.
Type of temperature measurement
This function determines the type of temperature measurement in
the hot-water tank.
In general, an electronic temperature sensor (immersion sensor in
hot-water tank) is used. The temperature is measured via the
change in resistance of this sensor here.
Alternatively, hot water provision can also be controlled by a
mechanical temperature controller (thermostat switching contact).
A hot-water thermostat is connected to tank sensor input and set
to the required setpoint hot-water temperature. When the
thermostat requires energy via the tank sensor input (contact
closed), the tank is loaded with hot water at the set hot water
maximum temperature until the contact opens again.
With hot water control through a thermostat, the current hot water
temperature cannot be measured and registered and will
therefore not be displayed as part of the system information. Also,
the hot water nominal temperatures cannot be set.
Hydraulic Components
189