Installation manual
128
4.2
4.2 Water Quality Requirements
Irrespective of any legal regulations, the ground water should not
contain any substances that could form deposits. Iron (<0.2 mg/
l) and Manganese (<0.1mg/l) limit values must be adhered to in
order to prevent iron ochre sedimentation in the heat source
system.
Experience has shown that contamination with grains larger than
1mm (organic components in particular) can easily cause
damage. Granular material (fine sand) does not deposit if the
specified water flows are adhered to.
The dirt trap included in the scope of supply of the heat pump
(mesh size 0.6mm) protects the evaporator of the heat pump; it
should be installed in the heat pump inflow.
ATTENTION!
Fine, colloidal contaminants that cause the water to become turbid also
tend to stick and can deposit in the evaporator, thereby impairing heat
transfer. These contaminants cannot be removed cost-efficiently using a
filter.
The use of surface water or water containing salt is not
permissible. Your local water utility can provide you with general
information regarding the possible use of ground water.
a) Water-to-water heat pumps with welded stainless steel
coil heat exchangers (to WI 27TE)
It is not necessary to carry out a water analysis with regard
to evaporator corrosion if the annual mean temperature of
the ground water is below 13 °C. In this case, the limit
values for iron and manganese must be adhered to (iron
ochre sedimentation).
For temperatures greater than 13°C (i.e. waste heat
recovery), a water analysis according to Table 4.2 on p. 128
must be carried out and the stability of the heat pump's
stainless steel evaporator should be determined. If one
characteristic in the column "stainless steel" is negative "-"
or two characteristics are "0", then the analysis should be
considered negative.
b) Water-to-water heat pumps with copper-soldered
stainless-steel plate heat exchangers (WI 40CG /
WI 90CG)
Irrespective of any legal regulations, a water analysis
according to Table 4.2 on p. 128 must be carried out to
determine the resistance for the heat pump's copper-
soldered evaporator. If one characteristic in the column
"copper" is negative "-" or two characteristics are "0", then
the analysis should be considered negative.
NOTE
If the necessary water quality is insufficient or if this cannot be
guaranteed long-term, it is recommended that a brine-to-water heat pump
equipped with an intermediate circuit is installed.
Table 4.2: Resistance of copper-soldered or welded stainless-steel plate heat exchangers to substances contained in the water
“+” normally good resistance;
„0“ corrosion problems can arise, particularly if several factors receive a evaluation of "0".
“-” should not be used [< smaller than, > greater than]
4.3 Tapping the Heat Source
4.3.1 Ground water as heat source
Extraction well
The ground water for the heat pump is extracted from the earth
via an extraction well. The well output must guarantee
continuous extraction to ensure the required minimum water flow
rate of the heat pump.
Evaluation
characteristic
Concentration
range (mg/l)
Copper
Stainles
s steel
> 13°C
Evaluation
characteristic
Concentration
range (mg/l)
Copper
Stainles
s steel
> 13°C
Substances that can
settle
(organic)
00 Oxygen
< 2
> 2
+
0
+
+
Ammonia
NH3
< 2
2 to 20
> 20
+
0
–
+
+
0
Hydrogen sulphide
(H2S)
< 0.05
> 0.05
+
–
+
0
Chloride
< 300
> 300
+
0
+
0
HCO3- / SO
4
2
-
< 1
> 1
0
+
0
+
Electr. conductivity
< 10 µS/cm
10 to 500 µS/cm
> 500 µS/cm
0
+
–
0
+
0
Hydrogen carbonate
(HCO3-)
< 70
70 to 300
> 300
0
+
0
+
+
0
Iron (Fe), dissolved
< 0.2
> 0.2
+
0
+
0
Aluminium (Al),
dissolved
< 0.2
> 0.2
+
0
+
+
Free (aggressive)
carbonic acid
<5
5 to 20
> 20
+
0
–
+
+
0
Sulphate
Up to 70
70 to 300
>300
+
0
–
+
+
0
Manganese (Mn),
dissolved
< 0.1
> 0.1
+
0
+
0
Sulphite (SO3), free < 1 + +
Nitrate (NO
3
),
dissolved
< 100
> 100
+
0
+
+
Chlorine gas (Cl2)
< 1
1 to 5
> 5
+
0
–
+
+
0
PH value
< 7.5
7.5 to 9
> 9
0
+
0
0
+
+