07/2015
Temperature Difference Controller TDC 3
Page 37 of 47
6.7 Anti-Legionella
With the “AL function” activated the TDC3 makes it possible to heat the storage tank up once
at certain intervals (the “AL frequency”) to a higher temperature (“AL Tset point S2”), assuming
that the energy source allows this.
AL function setting range: On or Off/default setting: Off
AL Tsetpoint S2 setting range: from 60 °C to 99 °C/default setting: 70 °C
AL frequency setting range: from 1 to 28 days/default setting: 7 days
AL Heat (not settable): Shows the last time the AL function was active
Caution
The anti-Legionella function is switched off at delivery. This function is only relevant
for storage tanks where sensor 2 is installed. Whenever heating-up has been
carried out with the anti-Legionella function switched on, an information message
with the date appears on the display.
Danger
During the anti-Legionella function the storage tank is heated up over the set
value “Tmax S2”, which can lead to scalding and damage to the system.
Caution
This anti-Legionella function does not provide complete protection against Legionella,
because the controller is dependent on sufficient energy being fed in, and it is not
possible to monitor the temperatures in the entire range of the storage tanks and the
connected piping system. To provide complete protection against Legionella bacteria,
it must be ensured that the temperature is raised to the necessary temperature, and
at the same time there must be water circulation in the storage tank and piping
system
by means of other additional energy sources and control units.
