Anti-Legionella Settings - andrews MAXXflo EVO Lite Installation And Maintenance Manual

1
B39
B3 3
Tab. 36
Line Description
1640 Legionella Function
1641 Legionella function periodically 7 days
1642 Legionella function weekday
1644 Legionella function time
1645 Legionella function setpoint
1646 Legionella function duration
1647 Legionella function circulation
pump
8 Operation

8.3.2 Anti-Legionella settings

1 B39 Return sensor
2 Q4 Return pump
3 B3 DHW Tank sensor
Q4 2
When activated via the heater controls, the anti-legionella function will
be satisfi ed when the DHW tank temperature sensor (B3) has detected
that the anti-legionella setpoint has been reached for the length of time
set (1646 Legionella function duration). If the optional return sensor
(B39) has been installed and Q4 pump is turned on during the function
(1647 Legionella function circulation pump), the temperature require-
ment to satisfy the function moves from the DHW tank sensor (B3) to the
return sensor (B39).
Important
In a return system where the heat losses are greater than 3°C,
the temperature reached at B39 sensor may never be enough to
confi rm that the anti-legionella setpoint has been achieved.
For example: If the legionella requirement was for a 70°C setpoint for 1
minute (see Tab 35 below) and the heat losses on the return system were
5°C, The temperature leaving the tank would be at a maximum of 73°C
(anti-legionella setpoint + maximum boost) and this would return to the
tank at 68°C. The anti-legionella function would never be satisfi ed in this
scenario and the controls would attempt to achieve the anti-legionella
setpoint for a total of up to 48 hours before resuming normal operation
and displaying an error message .
Tab. 35
Temperature
70°C
66°C
60°C
55°C
An alternative solution when return pipe system heat losses are high, the
B39 return sensor is installed and the Circulation pump Q4 is required to
be on is suggested as follows:-
1. Set "1612 Reduced setpoint" as the normal DHW tank temperature
(e.g. 60°C).
2. Set "1610 Nominal setpoint" as the temperature required for an anti-
legionella cycle (e.g. 70°C).
3. Set "5070 Automatic push" to OFF.
4. Use time program 4 to set the length of time and the day that you want
to run your anti-legionella cycle (every day is recommended) – For
guidance on the length of time required please refer to the Tab 35
Default Notes
Off Function activated or deactivated with this parameter
No of days before the legionella function will activate
Sunday Fixed day the legionella function will activate
01:00 Time the legionella function will activate
70 O C Setpoint to be achieved for legionella function
10 mins Length of time DHW tank sensors/B39 circulation return sensor (if fi tted) should
achieve the setpoint, before the function is completed. If setpoint not reached
within a 48 hour period, an error message will be displayed.
Off Circulation pump Q4 can be ON or OFF when the legionella function is active
See Tab. 36 below for typical settings
Time required at setpoint
1 MINUTE
2 MINUTES
32 MINUTES
6 HOURS
61 MAXXfl o EVO Lite