Installation and operating instruction
Oil condensing boiler WTC-OB 18-B
5 Installation
83311002 1/2018-03 La
22-132
5 Installation
5.1 Requirements for the heating water
In support of VDI guideline 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 max 25 μm).
The pH value must be 8.5 ±0.5.
There must be no oxygen enrichment of the heating water (max 0.02 mg/l).
With non-diffusion resistant system components, the appliance must be de-
coupled from the heating circuit by means of a separator.
5.1.1 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 ne-
cessary.
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
100 200 300 400 500 600 700 800 900 1000
0
2
4
6
8
10
12
14
1
2
1
Fill and top up water quantity [litres]
2
Total hardness [°dH]
