Dimplex LA 12 MI, Инструкция по установке и техническому обслуживанию

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Page 15
For efficient operation the DHW temperature should be
set to 45°C. Experience has found that this is more
than hot enough for showering and bathing.
If required, the hot water temperature can be set up to
75
º
C although this will utilise the immersion heater for
some of the heating period. By raising the storage
temperature, the volume of usable water is increased
which is useful is properties where a larger cylinder
can‟t physically be fitted.
The maximum temperature that the compressor can
achieve before the immersion needs to finish the
demand is variable based upon a number of factors. In
practice the LA MI heat pump is able to reduce its kW
output using the inverter compressor and can also
maintain its output above 55
º
C for a short period of
time.
It is therefore, not uncommon for the LA MI to achieve
cylinder temperatures of 50
º C using only the
compressor. It should however be noted that other
factors within the system can reduce the attainable
cylinder temperature so the customer expectation
should be managed to expect their hot water to be
stored at 45
º C.
The adjustable dial on the cylinder thermostat is not
wired in or used because the temperature of the
cylinder is controlled by a sensor. A notice such as that
shown in Figure 6 should be attached next to the
cylinder thermostat.
Figure 6: Notice to be fixed next to cylinder thermostat
Note that the manually resettable high temperature cut-
out in the cylinder thermostat is wired back to the heat
pump for G3 protection.
Sterilisation
For Domestic properties there is no official guidance on
the correct storage temperature or if thermal
sterilisation is required. There is a theoretical risk of
legionella growth, although no cases have yet been
reported in a domestic hot water system.
There is a trade off between maximising system
efficiency by reducing energy consumption and
minimising the theoretical risk of legionella growth. The
risk of legionella growth can be minimised by ensuring
that the cylinder does not remain stagnant for long
period of time. If the property is not occupied for a long
period, upon reoccupation, it would be prudent to raise
the cylinder temperature to 60°C and open the water
outlets to allow the connecting pipe work and outlets to
be sterilised.
For private domestic properties, Dimplex recommend
that the cylinder is raised to 60°C once per week
although the ultimate decision lies with the householder
to weight up the risk with the energy saving benefits.
For commercial properties the legislation requires for
the water to be stored at 60

C.
Secondary circulation pipes
A secondary circulation pipes is used to continuously
pump hot water around a closed loop, so that there is
not a long period of time from the taps opening to the
hot water being available. All of the EC-eau range of
cylinders larger than 210L feature a boss for connection
of a secondary return.
Heat consumption for a circulation pipe can be
considerable. The increase in consumption depends on
both the length of the circulation line and the quality of
the pipe insulation and on a large system should be
taken into account to ensure the heat pump is suitably
sized.
To maximise the efficiency of the system, if a circulation
system cannot be dispensed with because of long pipe
runs, the circulation pump should operate on a timed
basis.
The water drawn off immediately after
sterilisation will be much hotter than usual.
Consideration should be given to installing
a temperature limiting device at the outlets
to prevent scolding.
The schedule for sterilisation should be
determined by the installer to comply with
the necessary regulations.
TEMPERTURE ADJUSTMENT
The temperature of the hot water in this
cylinder is set using the wall mounted heat
pump controller. The setting shown on this
thermostat does not affect the hot water
temperature.
Setting the hot water temperature higher
than the heat pump alone can do with the
compressor would cause the immersion to
operate.
It is important to explain to an end user about
the correct cylinder temperature for economic
operation of the heat pump. They may have
previously been used to scolding hot
temperature that they mixed with cold water.