Grant Aerona 3 HPID10R32, Instructions Manual, Page: 21 / 100

Page 21 Section 5: Domestic Hot Water
5.3 LEGIONELLA
It is possible to use the heat pump to raise the HW cylinder to
around 50 to 55°C.
For protection against Legionella the temperature can be
periodically raised to 60°C using a 7-Day Immersion Programmer,
available from Grant UK (product code: HPIDT205).
This programmer also allows the cylinder immersion element to be
used to raise the temperature to 60°C for one hour either daily or
weekly to sterilise the cylinder against Legionella.
! NOTE !
For this system to operate, the existing immersion switch
must be left set permanently to ON.
To totally prevent operation of the immersion element, the
existing immersion switch must be set to OFF.
5.3.1 LEGIONELLA SANITISATION REGIME
Care must be given to vulnerable people who may be exposed
to potentially life-threatening legionella. This group of people
include the elderly, pregnant women, young children and those with
breathing difficulties.
Care must also be given to households who do not use a lot of
water on a daily basis. While this chart is not exhaustive, it is
important that you discuss any potential issues with the occupants
before deciding on the appropriate regime. It is important that
this decision is based on the welfare of the occupants and not on
energy saving measures.
Table 5-2: Legionella group sanitisation regime
Uses less than 50
litres of hot water
per day
Uses more than 50
litres of hot water
per day
Vulnerable Group
Store at 50°C and
raise hot water
cylinder to 60°C for 1
hour every day
Store at 50°C and
raise hot water
cylinder to 60°C for 1
hour every 3 days
Non-Vulnerable Group
Store at 50°C and
raise hot water
cylinder to 60°C for 1
hour every week
Store at 50°C and
raise hot water
cylinder to 60°C for 1
hour every 2 weeks
! WARNING !
If the hot water stored in the cylinder has not been used for a
prolonged period of time (e.g. a few days) and has not been
stored at 60°C, then it is important that the temperature is
raised to at least 60°C for a period of one hour before using
the hot water.
5.4 7-DAY IMMERSION PROGRAMMER
(LEGIONELLA)
This system uses the existing cylinder immersion heater, which is
switched via a small timeswitch enclosed in a separate unit to be
mounted next to the cylinder. Thus the immersion element can be
programmed to operate for the required period on either a daily or
weekly basis.
Once set, this system is fully automatic but can be overridden by
the user if required. Also, the user can still switch the immersion
element off, via the double pole isolation switch incorporated into
the design of the programmer (see Figure 5-1), irrespective of the
programmer or cylinder thermostat setting or whether the heat
pump is operating.
5.4.1 INSTALLATION
The Greenbrook T205-C timer (Grant UK product code: HPIDT205)
comes ready for installation. The connections to the Immersion
heater power supply and Immersion heater must be made after it is
installed on site.
When installed, this programmer interrupts the electrical supply
between the existing immersion heater power supply and immersion
heater. Refer to Figure 5-2 for electrical connection details.
! NOTE !
The Greenbrook T205-C immersion heater timer incorporates
a double pole isolation switch and a 13 Amp fuse into its
design.
For more detailed information on the installation of the Greenbrook
T205-C 7-day immersion programmer, please refer to the
instructions supplied with the programmer.
! WARNING !
Where a 3-phase supply is present, ensure that BOTH the
immersion heater power supply and heating system controls
are taken from the same phase. If in doubt, contact a
qualified electrician.
5.4.2 SETTING
For detailed information on setting the Greenbrook T205-C 7-day
immersion programmer, please refer to the instructions supplied
with the programmer.