SOLARFOCUS maximus L 150, Руководство по установке

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3 Technical requirements
Boiler
power
[In kW]
Minimum space [in cm²] including 20%
surcharge for grids
Austria Germany Switzerland
Supply
air
Exhaust
air
Supply
air/Exhaust
air
Supply air
20 kW
>240 >216
>180 >206
25 kW >180 >258
35 kW >180 >361
50 kW >228 >515
70 kW >228 >721
90 kW >276 >927
130 kW >347 >252 >372 >1339
200 kW >533 >336 >540 >2060
400 kW >1067 >576 >1020 >4120
3.6 Heating system fill-up water
In regard to the fill-up water quality, two key points
must be observed (in accordance with Guideline
VDI 2035):
–
Avoiding scale buildup (limescale)
–
Avoiding water-based corrosion (caused by oxy-
gen in the heating water)
The lowest possible corrosion acceleration rate of the
installed metallic materials is achieved by keeping the
circulation water in the correct pH range (8.2 to 9.5)
and, at the same time, having the lowest level of
electrical conductivity possible (50 to 100 µS/cm).
3.6.1 Avoiding scale buildup
What is scale buildup?
Scale buildup is the formation of firmly adhering depo-
sits on water-contacting walls of hot water heating
systems (e.g. the boiler heat exchanger surfaces).
This can subsequently lead to damage (stress cracks
in metal, leaks).
Causes of scale buildup
The cause of scaling is the presence of calcium carbo-
nate in the water.
The following calculation/table determines the total
permitted hardness of the fill-up water. If the value is
exceeded, the fill-up water must be treated, e.g. sof-
tened.
Calculation of the total permitted hardness of the
fill-up water
To use the table, the specific system volume for the
system must be determined:
System volume divided by total heat output results in
the specific system volume
1166 litres / 25 kW = 46.64 l/kW specific system
volume
Table: Total permitted hardness of the fill-up water
Total heat
output
Specific system volume (VDI 2035)
<20
l/kW
≥ 20 <50
l/kW
≥ 50
l/kW
< 50 kW ≤ 16.8°dH ≤ 11.2°dH < 0.11°dH
50 - 200 kW ≤ 11.2°dH ≤ 8.4°dH < 0.11°dH
20 - 600 kW ≤ 8.4°dH < 0.11°dH < 0.11°dH
> 600 kW < 0.11°dH < 0.11°dH < 0.11°dH
In our example: if the total hardness of the fill-up
water is more than 11.2 dH, then the fill-up water
must be treated.
3.6.2 Avoiding water-side corrosion
Corrosion is usually triggered by the available oxygen
in the water. This value can be brought into a safe
range with proper planning, design, installation and
maintenance of the heating system. A constant input
of oxygen should be avoided.
Important in this regard:
–
Expansion tank > 9 : Air must be prevented from
being drawn in when the heating system is coo-
ling down. Ensure:
–
Correct planning and implementation of the
expansion tank.
–
Regular check of the system pressure, expan-
sion tank pre-pressure.
–
Immediate repair of leaks in the heating system.
–
In the case of older underfloor heating, ensure
pipes are diffusion resistant
> 9
Check the pH of the fill-up water
–
The pH value must be between 8.2 and 9.5.
–
If this pH value does not self adjust after a week of
operation, it must be raised by adding 10 g/m³ tri-
sodium phosphate (Na3PO4) or 5 g/m³ sodium
hydroxide (NaOH). Allow 2 to 4 weeks of ope-
ration before further corrections.
–
Exception: If aluminium materials are used in the
heating system, a pH from 8.2 to 8.5 must be met
(pH> 8.5 increased corrosion tendency).
8 Installation manual maximus L