2.4.6 Return lift
If the hot water return is below the minimum return temperature, some of the hot water
outfeed will be mixed in.
CAUTION
Risk of dropping below dew point/condensation formation if operated without re‐
turn temperature control.
Condensation water forms an aggressive condensate when combined with com‐
bustion residue, leading to damage to the boiler.
Take the following precautions:
❒ Regulations stipulate the use of a return temperature control.
➥ The minimum return temperature is 65 °C. We recommend fitting some
sort of control device (e.g. thermometer).
2.4.7 Use with storage tank
NOTICE
In principle it is not necessary to use a storage tank for the system to run smooth‐
ly. However, we recommend that you use the system with a storage tank, as this
ensures a continuous supply of fuel in the ideal output range of the boiler.
For the correct dimensions of the storage tank and the line insulation (in accordance
with ÖNORM M 7510 or guideline UZ37) please consult your installer or Froling.
⇨ See "Addresses" [page 67]
2.4.8 Chimney connection/chimney system
EN 303-5 specifies that the entire flue gas system must be designed to prevent, wher‐
ever possible, damage caused by seepage, insufficient feed pressure and condensa‐
tion. Please note in this respect that flue gas temperatures lower than 160K above
room temperature can occur in the permitted operating range of the boiler.
The flue gas temperatures (for clean systems) and additional flue gas values can be
found in the table below.
The connection between the boiler and the chimney system should be as short as
possible. The upward angle of the connection should not exceed 30° - 45°. Insulate
the connection. The entire flue gas system - chimney and connection - should be cal‐
culated in accordance with EN 13384-1.
Local regulations and other statutory regulations also apply.
2
Safety
Design Information
10
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