17
3062547_201802
11 Information on water treatment
Example:
Limits in relation to specific system volume V
A
(V
A
= system volume / max. Rated heating output
1)
)
conversion, total hardness: 1 mol/m³ = 5.6 °dH = 10°fH
Total heating
output
V
A
≤ 20 l/kW
V
A
> 20 l/kW and < 50 l/kW
V
A
≥ 50 l/kW
Total hardness/
total alkaline earths
Conductivity
2)
at 25°C
Total hardness/
total alkaline earths
Conductivity
2)
at 25°C
Total hardness/
total alkaline earths
Conductivity
2)
at 25°C
[kW]
[°dH]
[mol/m³] C [µS/cm]
[°dH]
[mol/m³] C [µS/cm]
[°dH]
[mol/m³] C [µS/cm]
1
≤ 50
≤ 16,8
≤ 3,0
< 800
≤ 11,2
≤ 2
< 800
≤ 0,11
3)
≤ 0,02
< 800
2 50-200
≤ 11,2
≤ 2
< 100
≤ 8,4
≤ 1,5
< 100
≤ 0,11
3)
≤ 0,02
< 100
The total amount of fill and top-up water over the life cycle of the boiler must not exceed three times the nominal volume of the
heating system.
1)
According to VDI 2035, in systems with multiple boilers, use the maximum rated heating output of the smallest heat source
2)
High salinity < 800 µS/cm Low salinity < 100 µS/cm
3)
< 0.11°dH recommended standard; permissible up to limit of < 1°dH
System with a COB-20 system volume = 800 l
Total hardness of untreated potable water = 18°dH
V
A
= 800 l / 20 kW = 40 l / kW
Because the specific System volume V
A
is between 20 and 50 l/kW with a total output
of < 50 kW, the fill and top-up water must be in the range of 2 to 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.
A% desalinated water must be added.
A = 100% - [(C
max
-0.1°dH) / C
Potable water
- 0.1°dH)] x 100%
C
max
:
Maximum permissible total hardness in °dH
C
DHW
:
Total hardness of untreated potable water in °dH
A = 100% - [(11.2°dH - 0.1°dH) / (18°dH - 0.1°dH)] x 100% = 38%
38% of the filling and top-up water must be desalinated.
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.
Summary of Contents for COB
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