Connection On Heating Side; Water Quality In Heating Systems - Dimplex LI 1422C Installation And Operating Instruction

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6.3 Connection on heating side

The heating system connections on the heat pump have a
1 1/4" external thread. A spanner must be used to firmly grip
the transitions when connecting the heat pump.
CAUTION!
Fault on the safety switching equipment of the hydraulic
circuit intended for pressure limitation. Risk of injury!
 The safety switching equipment of the hydraulic circuit
intended for pressure limitation must be checked for
proper installation
commissioning.
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.
For systems in which the heating water flow rate can be shut off
via the radiator or thermostat valves, an overflow valve must be
installed by the customer in a heating bypass downstream from
the heat pump. This ensures a minimum heating water flow rate
through the heat pump and helps to avoid faults.
Once the heat pump has been connected to the heating sys-
tem, it must be filled, purged and pressure-tested.
6.4 Water Quality in Heating
Systems
6.4.1 Scale Formation
Scale formation in heating systems cannot be avoided, but in
systems with flow temperatures below 60 °C the problem is so
small that it is negligible. With high-temperature heat pumps
and in particular with bivalent systems in the higher perfor-
mance range (heat pump + boiler combination), flow tempera-
tures of 60 °C and more can be achieved. One preferred
method for preventing scale formation is softening because
this permanently removes alkaline earths (calcium and magne-
sium ions) from the heating system.
The following values for water quality in heating water and cold
water must be observed and checked during an on-site check:
Degree of hardness

Conductivity

 pH value
Filterable materials

The following (limit) values must absolutely be observed:
Maximum degree of hardness in filling water and supple-

mentary water 11 dGH.
 The conductivity in demineralised water (DM water) (low-
salt) may not be greater than 100 μS/cm.
The conductivity in partially demineralised water (saline)

may not be greater than 500 μS/cm.
The pH value must be between 8.2 and 9.

 The limit value for filterable materials in heating water is <
30 mg/l
If necessary, for example in bivalent systems, the specifications
listed in the table below must also be observed, or the precise
guidelines for filling water and supplementary water and the
total hardness must be taken from the table in accordance with
VDI 2035 – Sheet 1.
EN-10
and functionality before
452170.66.01-EN · FD 0303
NOTE
The specific volumes of a heating system must be determined
before filling the system.
The saturation index SI is used to determine whether water has
a tendency towards lime dissolution or lime separation. This
shows whether the pH value corresponds to a neutral pH point
or by how much it undershoots it due to excess acid or by how
much it exceeds it due to carbonic acid deficit. At a saturation
index below 0, the water is aggressive and will tend towards
corrosion. At a saturation index above 0, the water is calcare-
ous.
The saturation index SI should be between - 0.2 < 0 < 0.2
Filling and supplementary water as well as heating water, depending on
heat output
Overall heat output in kW
50
specific water content
2
heat generator > 0.3 k per kW
50
specific water content
2
heat generator > 0.3 k per kW
(e.g. circulating water heaters)
and systems with electric heat-
ing elements
> 50 kW to 200 kW
> 200 kW to 600 kW
> 600 kW
Heating water, depending on heating output
Operating mode
3
Low-salt
Containing salt
1. For the purpose of calculating the specific system volume, the smallest indi-
vidual heat output is to be used for systems with several heat generators.
2. In systems with several heat generators with different specific water con-
tents, the smallest specific water content is decisive.
3. Full softening is recommended for systems with aluminium alloys.
Fig. 6.1:Guideline values for filling and supplementary in accordance with
VDI 2035
CAUTION!
When using demineralised water, ensure that the minimum
permissible pH value of 8.2 is not undershot. Failure to comply
with this value can result in the heat pump being destroyed.
LI 1422C - 1826C
Total alkaline earths in mol/m³
(Total hardness in dGH)
 20 20 to 50 50
Specific system volume in l/kW
1
Heat output
3.0 (16.8)
none
 3.0 (16.8) 1.5 (8.4)
< 0.05 (0.3)
2.0 (11.2) 1.0 (5.6)
1.5 (8.4)
< 0.05 (0.3)
< 0.05 (0.3)
Electrical conductivity in µS/cm
> 10 to  100
> 100 to  1500
Appearance
clear, free from sedimentary substances
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