Description; General Information; Refrigerant Circuit (Heat Pump Operating Principle); Safety And Control Devices - Dimplex BWP 20A Instructions D'installation Et D'utilisation

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Description

2.1 General Information

The hot-water heat pump is a ready-to-use heating device and
mainly consists of hot water cylinders, the components for the re-
frigerant, air and water circuits, as well as all of the control, regu-
lation and monitoring devices required for automatic operation.
Using electrical energy, the hot-water heat pump heats water
using the heat stored in the air which is sucked in. Hot water heat
pumps have an additional ventilation function. The devices are
also equipped with an electric heating element (1.5 kW) as stan-
dard.
The temperature of the air sucked in (the heat source) is used as
reference value for energy consumption and DHW preparation
heat-up time.
For this reason, an air duct system (DN 125, max. length 10 m)
can be connected to the standard spigot of the hot-water heat
pump for specific waste heat recovery. In principle, effective op-
eration of the heat pump requires that there is no air short-circuit
between the air that is sucked in and the air that is blown out.
This can, for example, be achieved by a flexible air hose on the
intake and outlet side.
The falling temperature of the drawn-in air reduces the heat
pump output and extends the heating-up periods. Air inlet tem-
perature should not fall below 18 °C for economical heat pump
operation. If the temperature of the drawn-in air falls below 12 C
±1.5 (switch-back value 3 K) the heat pump is switched off.
Under this operating limit, domestic hot water preparation can be
carried out using a standard heating element (1.5 kW) by manual
regulation.
The electric heating element fulfils three additional
functions:
 Supplementary heating
The heating-up period is approx. halved by switching on the
heating element (using the switch "Heating Element") in ad-
dition to the heat pump.
Emergency heating

The water supply is maintained by the electric heating ele-
ment if the heat pump is out of order.
 Higher water temperature
If the required hot water temperature is higher than the tem-
perature achievable by the heat pump (approx. 60 °C), it can
be raised to a max. of 85 °C by using the heating element.
ATTENTION!
When the hot water temperature reaches > 60 °C, the heat pump switches
off. An additional hot water temperature increase can only be done by
switching on the heating element.The heating element controller is
factory set to 65 °C.
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2.2 Refrigerant Circuit (Heat Pump
Operating Principle)
The refrigerant circuit is a closed-loop system in which the refrig-
erant R134a is the energy source. The finned heat exchanger ex-
tracts heat from the air sucked in at a low evaporation tempera-
ture, and transfers it to the refrigerant. The vaporous refrigerant
is sucked in by a compressor where it is compressed to a higher
pressure and temperature level before being transported to the
liquifier, where the heat taken up in the evaporator and part of the
compressing energy is transferred to the water. Subsequently,
the high condensation pressure is lowered to the evaporation
pressure via a throttle mechanism (expansion valve). In the
evaporator, the refrigerant will again take up heat from the air
that is sucked in.

2.3 Safety and Control Devices

The hot-water heat pump has the following safety features:
High-pressure switch
The high-pressure switch protects the heat pump against imper-
missibly high operating pressure in the refrigerant circuit. In the
event of fault, the pressure switch will switch off the heat pump.
The heat pump is restarted automatically if there has been a
pressure drop in the refrigerant circuit.
Safety temperature limiter for heating element
(STL)
The STL protects the hot-water installation against impermissible
temperature increases.
The heating element is switched off if the set switching value
(99 °C) is exceeded.
The heating element cannot be re-started until the hot-water tem-
perature has decreased to  90 °C and the reset button (see il-
lustration) on the STL is pressed (this may be done by qualified
personnel only).
The hot-water heat pump is equipped with the following regula-
tion and control devices:
Heating element temperature controller (TC)
The heating element temperature controller regulates the hot
water temperature during heating element operation. The maxi-
mum controller temperature is factory set to 65 °C (the controller
and the STL are installed together in a casing). Temperature set-
tings can be changed using suitable tools (see Fig. in 2.3).
Changes to this setting may be carried out by qualified personnel
only!
2.3
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