Planning
16 | WOLF GmbH 3066501_201910
Calculation example
System with a COB-2-20
System volume = 800 L
Max. rated heating output for COB-2-20 = 20 kW
Total hardness of untreated potable water C
potable water
= 18 °dH
Specific system volume V
A
V
A
= system volume / max. rated heating output
V
A
= 800 L / 20 kW = 40 L/kW
Maximum permissible total hardness C
max
Table 4.3 Electrical conductivity and water hardness
The specific system volume V
A
is between 20 and 50 L/kW when the total output is < 50 kW.
The total hardness for the fill and top-up water C
max
must therefore be ≤ 11.2 °dH.
If the total hardness of the untreated potable water is too high, some of the filling and top-up water must
be desalinated.
Proportion of desalinated water A
A = 100 % ‒ [(C
max
‒ 0.1 °dH) / C
potable water
‒ 0.1 °dH)] • 100 %
A = 100 % ‒ [(11.2 °dH ‒ 0.1 °dH) / 18 °dH ‒ 0.1 °dH)] • 100% = 38 %
38% of the filling and top-up water must be desalinated.
Volume of desalinated water V
treatment
V
treatment
= A • system volume
V
treatment
= 38% x 800 L = 304 L
At least 304 L of desalinated water must be added when filling the system.
The system can then be topped up with potable water.
Top-up water
The total amount of filling and top-up water over the life cycle of the heat generator must not exceed three
times the nominal volume of the heating system (oxygen ingress!). If a system requires large volumes of
top-up water (e.g. more than 10 % of the system volume per year), the cause must be sought immediately
and the fault remedied.
4.3.3
WOLF
accessories - heating system
We recommend making the connection to the heating system with the following parts from the WOLF
accessories range.
Image
Item name
Connection kit COB-2 adjacent to wall
2 Cross pieces, each with one connection
2 Clips
1 Corrugated stainless steel pipe 1", length 1300 mm
1 Corrugated stainless steel pipe 1", length 800 mm
1 Silicone grease tube
Connection kit COB-2 with TS adjacent to wall
2 Cross pieces, each with two connections
4 Clips
3 Corrugated stainless steel pipes 1", length 1300 mm
1 Corrugated stainless steel pipes 1", length 800 mm
2 Corrugated stainless steel pipes ¾", length 800 mm
1 Silicone grease tube
1 Trimming set ¾"
1 Trimming set 1"
