5 Installation
5.1 Requirements for the heating water
In support of guideline VDI 2035 the following requirements are applicable for heating
water.
▪
Untreated fill and top-up water must be of domestic water quality (colourless, clear
and without any sedimentation),
▪
the fill and top-up water must be pre-filtered (mesh width max 25 µm),
▪
the pH value must be 8.5 ± 0.5,
▪
there must be no oxygen enrichment of the heating water (max 0.05 mg/l),
▪
in the case of diffusion resistant system components, the unit must be disconnec-
ted from the heating circuit by means of a separator.
5.1.1 Permissible water hardness
The permissible water hardness is determined in proportion to the fill and top up water
quantity.
▶
Determine from the diagram below whether water treatment measures are neces-
sary.
If the fill and top up water lies in the upper range of the limit curve:
▶
treat the fill and top-up water.
If the fill and top up water lies in the lower range of the limit curve, treatment is not
necessary.
▶
Record the fill and top-up water quantities in a system logbook.
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
0
2
4
6
8
10
12
14
16
18
20
1
Fill and top up water quantity in litres
2
Total hardness in °dH
Installation and operating instruction
Gas condensing boiler WTC-GB 90-A
5 Installation
83266502 • 1/2010-08 • La
22-95
