Anti-Legionella Protection

To kill bacteria in domestic hot water, the water temperature must be heated above 70 °C for a minimum period
(recommended 3 minutes).

This protection function is activated once the

We recommend connecting the input "LegionellaEnable" to a time schedule. This can be a short pulse to start the legionella function. If the protection function is active, the domestic hot water setpoint will be set to the anti-legionella function setpoint defined by the parameter LEG-01.

The output "LegionellaActive" will be "1" as long as the anti-legionella function is active. Optionally it can be connected to the primary district heat exchanger to increase the return water temperature setpoint.

When the secondary supply reaches the value of the legionella setpoint LEG-01 minus 50 % of the proportional band SST-06, the function will stop after a time delay defined by parameter LEG-03 "duration legionella".

The circulation temperature if connected must reach the legionella setpoint - 50% SST-06 - 5 K to trigger the legionella duration timer.

Legionella Protection Function Failed Alarm

When one of the secondary supply or circulation temperature sensors doesn't reach the anti-legionella target setpoint, within the time to reach legionella setpoint, an alarm is generated at the output "DHWS_Leg_Alm" and the anti-legionella function will be stopped. This alarm can be reset via the input "Reset" or by restarting the anti-legionella function.

Table 17.   Parameter List

Description

Value Range

Default Value

Unit

SST-06: P-band SST control

1...1000

20

K

LEG-01: anti-legionella setpoint

0...90

70

°C

LEG-02: time to reach legionella setpoint

0 = disable

0...3600

1800

sec

LEG-03: legionella duration

0...3600

600

sec

SYS-03: automatic/ manual reset

0 = auto

0 /1

1

-