Water quali ty/Frost protection
Unsuitable fil l and top-up water increases the level of deposits
and corrosion and may lead to boiler damage.
&
Thoroughly flush the entire heating system prior to filling it with
water.
&
Only use fill water of potable quali ty.
&
Soften fill water with a hardness above 3.0 mol/m
3
,e.g.withthe
small softening system for heating water (see the Viessmann
Vitoset pricelist).
&
An anti freeze additive suitable for heating systems can be
mixed with the fil l water. The antifreeze manufacturer must ver-
ify its suitability.
For furth er detai ls, see the VdTÜV datasheet 1466.
&
For initial start-up or systems with a volume in excess of 20
litres/kW, observe VDI 2035 and the technical guide "Standards
for water quality".
Drinking water quality
From a water hardness above 3.58 mmol/l and higher, we recom-
mend the use of a water treatment system in the cold water sup-
ply.
Secondary side connection to the Vitopend 222
The Vitopend is not suitable for use in conjunction with zinc-pla-
ted/galvanised pipes.
Sizing the diaphragm expansion vessel for heating water
A diaphragm expansion vessel is integrated i nto the Vitopend:
Inlet pressure 0.75 bar
Blow off pressure 3.0 bar
Terminal pressure 2.5 bar
Capacity 8 litres
Vitopend content 1.2 litres
When making the w ater connections, check that the s ize of the
expansion vessel matches the system cond itions.
Install a second expansion vessel on-site if the integral expansion
vessel is not large enough.
The foll owing steps will enable you to make a rough check.
Note
Adjust the inlet pressure to the static head prior to filling the sys-
tem.
Example:
A height differential of 5 m within the heating system results in an
inlet pressure of 0.5 bar.
Calculating the heating system volume
A Panel radiators
B Convector heaters
C Radiators
D Underfloor heating
Calculating expansion factor Af
Average heating water temp.
[°C]
Expansion factor
Af
50 0.0121
60 0.0171
70 0.0282
80 0.0295
Calculating pressure factor f
Inlet pressure
[bar]
System height
[m]
Pressure factor
f
1.0 10.0 2.4
0.75 7.5 2.1
0.5 5.0 1.8
5822 335-1 GB
VITOPEND 222 VIESMANN 31
Design information (cont.)
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