Sequence Of Legionella Function - Siemens Synco 700 Basic Documentation

Practical problems in
connection with legionella
protection
Starting the legionella
program
Ending the legionella
program
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Building Technologies
HVAC Products
The legionella protection function contradicts with requirements in terms of energy
savings, the formation of scale (the higher the storage tank temperature, the more
scale) and protection against scalding (above 60 °C).
Attention must be drawn to the risk of scalding when opening taps on completion of the
legionella function.

10.6.2 Sequence of legionella function

Using the legionella program, the DHW storage tank and, optionally, the circulation piping
(with the help of the circulating pump) can be maintained at the legionella protection
setpoint for the required period of time.
Legionella protection is also available with direct DHW heating, but a holiday time (period
of time legionella protection is provided) is possible only when the circulating pump runs.
The legionella program can be enabled either daily or weekly at a selectable point in
time.
As with forced charging, storage tank charging is started as soon as the storage tank
temperature (or one of the 2) lies 1 K below the legionella protection setpoint.
The legionella program will not be performed in the following cases:
• When the DHW operation selector is set to Protection mode
• During holiday mode when the selected DHW holiday mode is Protection
• When the DHW operating mode contact forces DHW heating to Protection mode
• When the plant operation selector is set to "Off"
• When storage tank charging is effected with an electric immersion heater, but with-
out storage tank sensor
If, during the period of time the legionella protection program is performed, the storage
tank temperature (or both storage tank temperatures) can be kept at the required
setpoint, the legionella function will be ended.
If, in addition, consumer control with a circulating pump has been configured, the
consumer's flow temperature sensor is also required to acquire the legionella protection
setpoint for the legionella protection period. If the circulating pump is switched off
during the time the legionella function is active, consumer control will be exempted from
legionella protection.
The legionella function is ended only when, during the time of legionella protection, all
temperatures have been at their legionella protection setpoint, or above it.
TDhw
TDhwSetpt
TDhwSetpt - SDDhw
TDhwSetpt - SDDhw - 2 K
ON
1
OFF
ON
2
OFF
3
Switching differential DHW heating
SDDhw
t
Time
TDhw DHW temperature
TDhwSetpt DHW temperature setpoint
TiLegioHld Holding time of legionella function (period of time legionella protection is provided)
Circulating pump
Enabling the legionella function
Start conditions for legionella function satisfied
Modular Heating Controller RMH760B
10 DHW heating
TiLegioHld TiLegioHld
t
CE1P3133en
05.02.2007