24
Fill water
According to EN 1717 with DIN 1988-100, as a heat
transfer medium for DHW heating, the heating water
must meet fluid category ≤ 3. This requirement is met if
water of potable quality is used as heating water. For
example, if additives are used, the additive manufac-
turer must specify which category the treated heating
water comes under.
!
Please note
Unsuitable fill water increases the level of
deposits and corrosion and may lead to appli-
ance damage.
■
Flush the heating system thoroughly before
filling.
■
Only use fill water of potable water quality.
■
Special antifreeze suitable for heating systems
can be added to the fill water. The antifreeze
manufacturer must verify its suitability.
■
Fill and top-up water with a water hardness in
excess of the following values must be soft-
ened, e.g. with a small softening system for
heating water.
Total permissible hardness of the fill and top-up water
Total heating output
Specific system volume
kW
< 20 l/kW
≥
20 l/kW to < 50 l/kW
≥
50 l/kW
≤
50
≤
3.0 mol/m
3
(16.8 °dH)
≤
2.0 mol/m
3
(11.2 °dH)
< 0.02 mol/m
3
(0.11 °dH)
>
50 to
≤
200
≤
2.0 mol/m
3
(11.2 °dH)
≤
1.5 mol/m
3
(8.4 °dH)
< 0.02 mol/m
3
(0.11 °dH)
>
200 to
≤
600
≤
1.5 mol/m
3
(8.4 °dH)
≤
0.02 mol/m
3
(0.11 °dH)
< 0.02 mol/m
3
(0.11 °dH)
>
600
< 0.02 mol/m
3
(0.11 °dH)
< 0.02 mol/m
3
(0.11 °dH)
< 0.02 mol/m
3
(0.11 °dH)
Fig. 22
1.
Check the pre-charge pressure of the diaphragm
expansion vessel.
If the pre-charge pressure is lower than the static
system pressure, top up with nitrogen. The pre-
charge pressure must be 0.1 to 0.2 bar (0.01 to
0.02 MPa) higher. If the pre-charge pressure is too
high, adjust it accordingly.
2.
Open the non-return valves.
3.
Fill the heating system with water and vent the sys-
tem. The charge pressure must be 0.1 to 0.2 bar
(0.01 to 0.02 MPa) higher than the pre-charge
pressure of the diaphragm expansion vessel.
Permissible operating pressure: 3 bar (0.3 MPa)
Test pressure: 4 bar (0.4 MPa)
4.
Mark the charge pressure at pressure gauge
A
.
5.
Return the non-return valves to their operating
position.
Checking all connections on the heating water side for leaks
Commissioning, inspection, maintenance
Filling the heating system
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