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7.3 Heating System Connection
Before connecting the heating water system to the heat pump,
the heating system must be flushed to remove any impurities,
residue from sealants, etc. Any accumulation of deposits in the
liquifier could cause the heat pump to completely break down.
CAUTION!
The supplied dirt trap should be installed in the return before
the heat pump.
With the insertion piece with cap nut (also supplied), the dirt
trap can be flush-mounted directly on the heat pump return.
An overflow valve is installed in the device for systems in which
the heating water flow can be shut off via the radiator or ther-
mostat valves. This ensures a minimum heating water flow rate
through the heat pump and helps to avoid faults.
Once the heating system has been installed, it must be filled,
de-aerated and pressure-tested.
Consideration must be given to the following when filling the
system:
Untreated filling water and make-up water must be of
drinking water quality (colourless, clear, free from sedi-
ments)
Filling water and make-up water must be pre-filtered (pore
size max. 5 µm).
Scale formation in domestic hot water heating systems cannot
be avoided, but in systems with flow temperatures below 60 °C,
the problem can be disregarded. With high-temperature heat
pumps and in particular with bivalent systems in the higher per-
formance range (heat pump + boiler combination), flow tem-
peratures of 60 °C and more can be achieved. The following
standard values should therefore be adhered to with regard to
the filling and make-up water according to VDI 2035, sheet 1:
The total hardness values can be found in the table.
Total alkaline earths
Total heat
in mol/m³ and/or
output in kW
mmol/l
2.0
< 50
2.0
50 - 200
200 - 600
1.5
> 600
< 0.02
1. This value lies outside the permissible value for heat exchangers in heat
pumps.
Fig. 7.1:Guideline values for filling and make-up water in accordance with
VDI 2035
For systems with an above-average specific system volume of
50 l/kW. VDI 2035 recommends using fully demineralized
water and a pH stabiliser to minimize the risk of corrosion in the
heat pump and the heating system.
CAUTION!
With fully demineralized water. it is important to ensure that
the minimum permissible pH value of 7.5 (minimum
permissible value for copper) is complied with. Failure to
comply with this value can result in the heat pump being
destroyed.
EN-8
Specific system volume
(VDI 2035) in l/kW
< 20
20 < 50
50
Total hardness in °dH
16.8
11.2
11.2
8.4
1
< 0.11
8.4
1
< 0.11
1
< 0.11
452160.66.75a · FD 0112
The integrated expansion vessel has a volume of 24 litres.
The volume should be checked by the heating system engi-
neer. If necessary. an additional expansion vessel must be in-
stalled (according to DIN 4751. Part 1). The tables listed in the
manufacturers' catalogues simplify dimensioning the system
on the basis of the water content. Allow for a buffer tank volume
of 55 litres when making the calculation.
CAUTION!
In the case of large-volume heating circuits. an additional
expansion vessel must be used to supplement the installed
expansion vessel (24 litres. 1.0 bar admission pressure).
Minimum heating water flow rate
The minimum heating water flow rate through the heat pump
must be assured in all operating states of the heating system.
When the minimum heating water flow rate is undershot. the
plate heat exchanger in the refrigeration circuit can freeze.
which can lead to total loss of the heat pump.
The nominal flow rate is specified depending on the max. flow
temperature in the device information and must be taken into
account during planning. With design temperatures below
30 °C in the flow. the design must be based on the max. volume
flow with 5 K spread for A7/W35.
The specified nominal flow rate (See "Device Information" on
page 13.) must be guaranteed in every operating status. An in-
stalled flow rate switch is used only for switching off the heat
pump in the event of an unusual and abrupt drop in the heating
water flow rate and not to monitor and safeguard the nominal
flow rate.
Antifreeze
Heat pump systems. which cannot be guaranteed to be frost-
free. should be equipped with a drainage option (see Fig.). The
antifreeze function of the heat pump manager is active when-
ever the heat pump manager and the heat circulating pump are
ready for operation. When decommissioning the heat pump, or
in the event of a power failure, the system must be drained
through the indicated points (see illustration); it may be neces-
sary to purge the system with compressed air. If heat pump
systems are implemented in buildings where a power failure
cannot be detected (holiday homes etc.), the heating circuit
should be operated with suitable frost protection.
1
2
LIK 12TU
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