Technical data

7.4.3
50
temperature range between min. 10 °C and max. 40°C. The heat
pump cools until the set return temperature is reached and then
shuts off automatically. If the return temperature rises by 4 Kelvin
above the set return temperature, the heat pump switches on
again automatically.
The heat pump also switches itself off if the heating water
reaches a flow temperature of approx. 7 °C or the air intake
temperature exceeds the upper operating limit.
After the heat pump has switched off, a restart of the cooling
operation is only possible after an idle time of 5 minutes. The
observation of this time interval is ensured by the control of the
heat pump.
To prevent condensation from forming on parts of the heat pump
system, it is recommended to monitor sensitive points of the cold
distribution system with the help of a dew point monitor and
corresponding dew point sensors. The cooling operation is
interrupted if the dew points sensors register humidity build-up
(see chapter 10, accessories).
Exception of room temperature control
(only LAK 10MR)
The room temperature control in cooling operation works
identically to the regulation in heating mode. Turn the rotary knob
(4) to preselect the desired room temperature. The request also
takes place via the potentiometer at the same temperature range
between min. 15 °C and max. 25 °C. The level required for the
cooling water is calculated from the deviation in the room
temperature. The heat pump is shut off when the set room
temperature has been reached. The heat pump is switched on
again when the room temperature rises by 2 Kelvin above the set
setpoint.
7.4.3 Hot water preparation operating mode
Start the heat pump by turning the switch (1) to the ON position
(I). Hot water can be prepared with the heat pump independently
of the currently set operating mode. The request must be
presented with the help of external thermostats to be provided in
the hot water cylinder. The request signal generated by the
thermostat is processed by the control of the heat pump by
switching the three-way reversal valve, required for hot water
preparation, and setting the return set temperature automatically
to the maximum value.
The request for hot water preparation has the highest priority so
that a possibly existing or occurring heating or cooling request is
put on hold for the duration of the hot water preparation. After the
hot water preparation has been concluded, an existing request
for heating or cooling is then resumed or the heat pump switches
off.
NOTE
The heat exchanger area installed in the hot water cylinder must be
dimensioned so that the maximum heat output of the heat pump can be
transferred when the temperature spread remains under 10 K. The heat
output especially of air-to-water heat pumps rises with the external
temperature. The required heat exchanger area of the hot water cylinder
must therefore be designed for the heating output of a heat pump in the
summer (outside temperature approx. 25 °C).
PAY SPECIAL ATTENTION TO:
If the hot water set temperature on the thermostat is set to a
value that is too high, this causes the heat pump to be shut off via
the high-pressure switch and the heating or cooling operation is
blocked.
7.5 Special accessories
7.5.1 Domestic hot water preparation
Hot water cylinder requirements
The standard continuous power ratings specified by the different
cylinder manufacturers are not a suitable criterion for selecting a
cylinder for heat pump operation. The following criteria must be
taken into consideration when selecting a cylinder: the size of the
heat exchanger area, the construction, the arrangement of the
heat exchangers in the cylinder, the continuous power rating, the
flow rate and the installation position of the thermostat.
The following criteria must be taken into
consideration:
 The heat output of the heat pump at the maximum heat
source temperature (e.g. air +35 °C) must also be
transferable at a cylinder temperature of +45 °C.
 The cylinder temperature is lowered when a circulation pipe
is used. The circulation pump should be time-controlled.
 It must be possible to tap the required amount of hot water
even during shut-off times without the heat pump having to
reheat.
Hot water cylinder minimum requirements
(On the basis of the integration set-ups recommended in this
manual and standard boundary conditions)
The table shows the allocation of hot water cylinders to the
individual heat pumps where a hot water temperature of approx.
45 °C is reached by the operation of the heat pump (max.
temperatures of the heat sources: Air: 25 °C, Brine 15 °C).
The maximum hot water temperature that can be attained with
heat-pump-only operation is dependent on:
 The heat output of the heat pump
 The heat exchanger area in the cylinder
 The volume flow in relation to the pressure drop and the
capacity of the circulating pump.
NOTE
Higher temperatures can be reached by larger exchanger areas in the
cylinder and/or by increasing the volume flow.
Heat pump Volume Order designation
LA 6MR / LA 8MR / LA 10MR 300 l WWSP 332 / PWS 332
LA 12TR / LA 16TR 400 l WWSP 880
SI 8MR / SI 10MR / SI 12TR 300 l WWSP 332 / PWS 332
SI 14TR / SI 16TR 400 l WWSP 880
SI 20TR 500 l WWSP 900