Technical data
110 | Project planning manual for heat pumps for heating and domestic hot water preparation | 01.2012 www.dimplex.de
8.10 Integration of the heat pump in the heating system
8.10 Contaminants in the heating system
When installing a heat pump in a new or existing heating system,
the system should be flushed to remove deposits and suspended
matter. These types of contaminants can reduce the heat trans-
fer of the radiators, impede the flow or collect in the condenser of
the heat pump. In extreme cases, they can cause the heat pump
to switch off automatically. Oxidation products (rust) can form if
oxygen enters the heating water. Contamination caused by rem-
nants of organic lubricants and gasket material can also occur
frequently. Both sources of contamination can lead - either indi-
vidually or together - to a reduction in the efficiency of the heat
pump's condenser. In such cases, the condenser must be
cleaned.
Detergents should only be used with caution because of their
high acid content. The regulations of relevant employers' liability
insurance associations should be observed. Always consult the
manufacturers of the chemicals in case of doubt!
ATTENTION!
The heating system should be neutralised with suitable chemicals after
cleaning to avoid subsequent damage.
The heat pump should generally be disconnected from the heat-
ing system before flushing. Isolating valves should be fitted in the
flow and return to prevent the heating water from leaking. The
water connections on the heat pump are used for flushing.
In the case of heating systems equipped with steel components
(e.g. pipes, buffer tank, boiler, manifold, etc.), there is always the
danger of excess oxygen causing corrosion. This oxygen enters
the heating system via the valves, the circulating pumps and/or
plastic pipes.
NOTE
We therefore recommend equipping diffusion-open heating system with
an electrophysical anti-corrosion system. According to today's state of
knowledge, an ELYSATOR system is well suited for this kind of use.
8.11 Integration of additional heat generators
8.11.1 Constantly regulated boiler (mixer regulation)
When implementing this type of boiler, the boiler water is always
heated to a set temperature (e.g. 70 °C) when the command is
issued accordingly by the heat pump manager. This temperature
must be set so high that domestic hot water preparation can also
be carried out by the boiler (according to need).
Regulation of the mixer is undertaken by the heat pump man-
ager. If required, it calls for the boiler and adds more domestic
hot water until the desired set return temperature or domestic hot
water temperature is reached.
The boiler is called via the 2nd heat generator output of the heat
pump manager and the mode of operation of the 2nd heat gen-
erator is coded as being "constant".
NOTE
When the special program heat generator 2 is activated, the boiler is
maintained at operating temperature for at least 30 hours after the com-
mand is issued to prevent corrosion caused by short runtimes.
8.11.2 Variably regulated boiler (burner regulation)
In contrast to constantly-regulated boilers, variably-regulated
boilers supply domestic hot water at a temperature that is directly
based on the respective outside temperature. The three-way re-
versing valve has no regulatory function. However, it has the task
of directing the heating water flow past or through the boiler, de-
pending on the operating mode. In the case of heat-pump-only
operation, the heating water is directed past the boiler to avoid
losses caused by heat dissipation of the boiler. No separate
burner regulation is required for bivalent systems because con-
trol can be undertaken by the heat pump manager. If the system
is equipped with atmospherically controlled burner regulation,
the voltage supply for burner regulation should be disconnected
in the case of heat pump only operation. The boiler is controlled
via the 2nd heat generator output of the heat pump manager,
and the mode of operation of the 2nd heat generator is coded as
being “variable”. The characteristic curve of the burner regulation
is set according to the heat pump manager.
NOTE
It is not possible to control an additional immersion heater for supple-
mentary heating (E10.1) in a bivalent system.
Fig. 8.26: Circuit diagram for variably-regulated boiler operation
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