Domestic Hot Water - Fröling SP Dual compact Installation Instructions Manual

3 | Design Information

3.6 Domestic hot water

14
Unless contrary to other national regulations, the latest versions of the following
standards and guidelines apply:
Austria: ÖNORM H 5195
Germany: VDI 2035
Observe the standards and also follow the recommendations below:
r Aim for a pH value of between 8.2 and 10.0. If the central heating water comes into
contact with aluminium, the pH value must be between 8.0 and 8.5
r Use prepared water which complies with the standards cited above for filling and
make-up water
r Avoid leaks and use a closed heating system to maintain water quality during
operation
r When filling with make-up water, always bleed the filling hose before connecting, in
order to prevent air from entering the system
Advantages of prepared water:
▪ Complies with the applicable standards
▪ Less of a drop in output due to reduced limescale build-up
▪ Less corrosion due to fewer aggressive substances
▪ Long-term cost savings thanks to improved energy efficiency
Permitted water hardness for the fill and make-up water in accordance with VDI
2035:
Overall Total hardness at
heat output <20 l/kW minimum
individual heat output
kW °dH
≤50 no demand or
2)
<16.8
>50 ≤200 11.2
>200 ≤600 8.4
>600 0.11
1. From specific system volume (litres nominal capacity/heat output; for multi-boiler systems use the smallest individual heat output)
2. In the case of systems with central heating boilers and for systems with electric heating elements
Total hardness at
>20 ≤50 l/kW minimum
1)
individual heat output
mol/m³ °dH
11.2
2)
<3
2 8.4
1.5 0.11
0.02
M1820921_en | Installation instructions Dual fuel boiler SP Dual compact
Switzerland: SWKI BT 102-01
Italy: UNI 8065
Total hardness at
>50 l/kW minimum
1)
individual heat output
mol/m³ °dH
2 0.11
1.5
0.02
1)
mol/m³
0.02