2 Safety information
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 Room sealed operation (RS)
Basic information
In conventional boiler Installation rooms, the
necessary supply air openings from outdoors lead to
uncontrolled heat loss. This is prevented by room-
sealed (RS) boilers, as the combustion air is drawn in
from outside in closed supply air lines directly into the
boiler and not in the installation room.
RS line integrated in chimney
The recommended variant: The intake air is taken in
from outside of the chimney pipe down to the boiler.
RS line outside of the chimney
–
Fire-rated insulation with rockwool required if the
RS line passes through other rooms.
–
Cold insulation of the RS line within building ele-
ments (wall, floor, etc.) required to avoid damage
to the building from condensate.
–
Further information: standard EN 15287-2
►
Establishing the room-sealed connection
3.7 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-side corrosion (caused by oxygen
in the heating water)
The lowest possible rate of corrosion of the installed
metal materials is primarily achieved when the circula-
tion water is in the correct pH range (8.2 to 9.5) while
at the same time, the electrical conductivity (50 to 100
µS/cm) is as low as possible.
3.7.1 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.
8
Installation manual
pelletelegance
