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LA 25TU-2 - LA 40TU-2
6.2 Connection on heating side
The heating system connections on the heat pump are to be
made inside the device. Refer to the device information for the
connection sizes. Route the connection hoses out of the device
in a downwards direction. An optional pipe kit is available as an
accessory, which can be used to lead the connections out to the
side.
Use a spanner to firmly grip the transitions when connecting the
heat pump.
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
liquefier could cause the heat pump to completely break down.
ATTENTION!
!!
The dirt trap included in the scope of supply is to be installed in the heat
return before the heat pump.
Cleaning and maintenance instructions can be found in the dirt
trap's installation and operating instructions.
Once the heat pump has been connected to the heating system,
it must be filled, de-aerated and pressure-tested.
Consideration must be given to the following when filling the sys-
tem:
Untreated filling water and make-up water must be of drink-
ing water quality (colourless, clear, free from sediments)
Filling water and make-up water must be pre-filtered (pore
size max. 5µm).
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 performance
range (heat pump + boiler combination), flow temperatures 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 hard-
ness values can be found in the table.
Fig. 6.1: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.
ATTENTION!
!!
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.
Minimum heating water flow
The minimum heating water flow rate through the heat pump
must be assured in all operating states of the heating system.
This can be accomplished, for example, by installing either a dual
differential pressureless manifold or an overflow valve. The pro-
cedure for setting an overflow valve is described in the chapter
"Start-up". When the minimum heating water flow rate is under-
shot, 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 ac-
count 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.
NOTE
º
The use of an overflow valve is only recommended for panel heating and
a max. heating water flow of 1.3 m³/h. System faults may result if this is
not observed.
Antifreeze
Heat pump systems, which cannot be guaranteed to be frostfree,
should be equipped with a drainage option (see Fig.). The anti-
freeze function of the heat pump manager is active whenever the
manager and the heat circulating pump are ready for operation.
The system has to be drained if the heat pump is taken out of ser-
vice or in the event of a power failure. The heating circuit should
be operated with a suitable antifreeze if heat pump systems are
implemented in buildings where a power failure cannot be de-
tected (holiday home).
Total heat
output in kW
Total alkaline
earths in mol/m³
and/or mmol/l
Specific system volume
(VDI 2035) in l/kW
< 20
20 < 50
50
Total hardness in °dH
< 50
2,0
16,8
11,2
< 0,11
50 - 200
2,0
11,2
8,4
200 - 600
1,5
8,4
< 0,11
> 600
< 0,02
< 0,11
1
1. This value lies outside the permissible value for heat exchangers in heat
pumps.
1
2
3
Summary of Contents for LA 25TU-2
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