KWB Easyfire - Page 45

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Heating system fill water
The directive VDI 2035
contains clear specifications for heating system fill water for preventing
damage in hot water heating systems: It should be low-salt and alkaline and not exceed a spe-
cific hardness.
Maximum total hardness in dependence of the specific system volume
dH mval/l mmol/l fH
Total heat output < 20 l/kW
< 50 kW 16,8 6 3 9,4
50-200 kW 11,2 4 2 6,3
Total heat output 20–50 l/kW
< 50 kW 11,2 4 2 6,3
50-200 kW 8,4 3 1,5 4,7
Total heat output > 50 l/kW
< 50 kW 0,11 0,04 0,02 0,06
50-200 kW
("dH" … German hardness, "fH" … French hardness)
Deposits caused by limescale and rust mud can block pumps, damage boilers, reduce flow vol-
umes, cause corrosion and lead to a poor efficiency.
Savings of up to 30 % are possible if the heating water energy source corresponds to the valid
directive VDI 2035 and is filled with appropriate care.
The VDI 2035 dictates (VDI 2035 Sheet 2 No. 8.3.3) that the system operator document the
steps from the planning, to the commissioning, to the maintenance in a "System book" (VDI
2035 Sheet 2 Appendix C).
This table records only the initial filling respectively all additions of water:
Date Meter reading Z
0
[m³] Sum alkaline earth
[mol/m³] resp. total de-
gree of hardness
Signature
Meter reading
Z
NEW
[m³]
Water amount
Z
NEW
[m³] – Z
0
[m³]
7.1.5.2
Maintenance
7
Standards for maintenance
B KWB Easyfire EN, 05.2011
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