Heating System Connection; Frost Protection - Bosch LWPS 3 Instructions D'installation Et D'utilisation

LWPS 3 - LWPS 14
5.3

Heating system connection

The heating system connections on the indoor unit have a 1"
flat sealing external thread. A spanner must be used to firmly
grip the transitions when making the connections.
There is a hose sleeve on the safety valve for on-site connection
of a plastic hose. This should be fed into a siphon or outflow.
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 may cause the heat pump to completely break down.
Once the heat pump has been connected to the heating sys-
tem, it must be filled, purged and pressure-tested.
The following points must be observed when filling the system:
Untreated filling water and make-up water must be of

drinking water quality
(colourless, clear, free of sediments)
Filling water and make-up water must be pre-filtered (max.

pore size 6 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
1.5
200 - 600
> 600 < 0.02
1. This value lies outside the permissible value for heat exchangers in heat
pumps.
Fig. 5.1: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.
NOTE
If the unit is connected to an existing hydraulic water circuit,
the hydraulic pipes must be cleaned to remove residues and
limescale.
The heating circuit must include a corresponding purging facil-
ity, a fill and drain valve and a dirt trap on-site.
It is also recommended to install a shut-off device in the return
before integration into the indoor unit is carried out.
www.boesch.at
Specific system volume
(VDI 2035) in l/kW
20 < 50 50
< 20
Total hardness in °dH
16.8 11.2
 11.2 8.4
< 0.11
8.4
1
< 0.11
1
< 0.11
452162.66.16a · FD 0108
Minimum heating water flow rate
The minimum heating water flow rate must be ensured in all op-
erating states of the heating system with at least 50 l (buffer
tank with individual room control or underfloor heating system
with 50 l minimum volume in open heating circuits). 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.
NOTE
The installation of a flow rate switch (DFS LAK or VSH LAK) is
absolutely necessary to ensure water flow before compressor
start and during defrosting.
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 18.) must be assured in all operating states. An installed
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.

Frost protection

A method of manual drainage must be provided for heat pump
internal components which are exposed to frost. The frost pro-
tection function of the heat pump manager is active whenever
the heat pump manager and the heat circulating pump are
ready for operation. The system has to be drained if the heat
pump is taken out of service or if a power failure occurs. The hy-
draulic network should be operated with suitable frost protec-
tion if heat pump systems are implemented in buildings where
1
a power failure cannot be detected (vacation homes etc.).
NOTE
Chemical treatment to protect from rust should be carried out
by the installer.
English
EN-7