Section 11: Domestic Hot Water
Page 39
•
50°C for normal hot water heating
•
60°C for one hour either daily or weekly to sterilise the cylinder
against Legionella
Refer to Section 11.2.1 for details of how to assess the
Legionella sanitisation regime required for the installation
concerned.
A Grant heat pump cylinder, with a larger primary coil, MUST be
fitted when using this hot water control option.
Refer to Section 12, Figure 12-9 for wiring details.
For further details of the Grant Digital two-stage Cylinder thermostat
(Grant UK product code: GCSD2), refer to Section 11.4.
There must be a demand from the HW channel of the heating/
hot water programmer for the automatic anti-legionella
function of the Digital two-stage cylinder themostat to
operate. When setting the ON period(s) on the two-stage
cylinder thermostat timeswitch, ensure that they are within a
HW ON period on the programmer.
NOTE
!
With this hot water control system, the heat pump of the
VortexAir hybrid unit will NOT operate to heat the hot water
cylinder, in response to a DHW demand, unless the Oil/Hybrid
switch is set to ‘Hybrid’.
NOTE
!
Boiler only installations (heat pump not yet installed)
This hot water control system will NOT operate to heat the hot water
cylinder, in response to a DHW demand, when only the boiler is
installed (i.e. with no heat pump installed or connected).
A
temporary
change MUST be made to the control system
connections at the Heating system controls terminal block (in the
hybrid control panel) in order for the hot water heating function to
operate. Refer to Section 12.3.3 for details.
As soon as the heat pump is installed and connected to
the boiler, this temporary change to the control system
connections MUST be reversed. Refer to Section 12.3.2 for
details.
!
CAUTION
11.2 Legionella
It is possible to use the heat pump of the VortexAir hybrid to raise
the HW cylinder to around 50 to 55°C.
For protection against Legionella the temperature should be
periodically raised to 60°C.
This can be achieved by either:
•
Using the Grant Automatic DHW Boost Kit 2, available from
Grant UK (product code: HPDHWBK2), as mentioned in
section 11.1.2 above.
OR
•
Using the Grant digital two-stage cylinder thermostat with
built-in timer function, also available from Grant UK (Grant UK
product code: GCSD2), as mentioned in Section 11.1.3.
11.2.1 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 11-1:
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
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.
!
WARNING
11.3 Grant Automatic DHW Boost Kit 2
This system uses both the existing cylinder immersion heater and
cylinder thermostat. This is switched via a contactor operated by
a small digital timeswitch, both 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 immersion heater switch, irrespective of the programmer
or cylinder thermostat setting or whether the heat pump is operating.
11.4 Grant Digital 2-Stage Cylinder Thermostat
This consists of a digital two-stage thermostat, a single channel
digital timeswitch and relay fitted in an eletrical enclosure.
The digital temperature controller (on the front panel of the
thermostat enclosure) allows the setting of two temperatures in the
HW cylinder:
•
Normal hot water heating using the heat (factory default: 50°C)
•
High temperature to sterilise the cylinder against Legionella
using the boiler (factory default: 60°C)
Refer to the Installation Instructions supplied with the Grant digital
two-stage Cylinder Thermostat for details on how to set the digital
temperature controller, if required.
The frequency and length of the high temperature anti-legionella
operation is controlled by a digital timeswitch located inside the two-
stage cylinder thermostat enclosure.
Refer to the Installation Instructions supplied with the Grant digital
two-stage Cylinder Thermostat for details on how to set the digital
timeswitch.
There must only be ONE demand, for either heating (CH) or
hot water (HW), on the VortexAir hybrid at a time. In all cases,
the DHW demand MUST not clash with the CH demand,
i.e. set the programmer such that the HW ON period(s) are
different from the CH ON period(s) and do not overlap each
other.
!
WARNING
Summary of Contents for Aerona3 Series
Page 57: ...Section 13 Flue System and Air Supply Page 57 Figure 13 8 Flue clearances...
Page 77: ...Section 19 Spare Parts Page 77 Figure 19 4 15 21kW baffles Figure 19 5 21 26kW baffles...
Page 84: ...Appendix A Page 84 Appendix A...
Page 85: ...Appendix A Page 85...
Page 86: ...Appendix A Page 86...
Page 87: ...Appendix A Page 87...
