Dimensions and clearances
Trade name
Vitoflex 300-UF
Rated heating output
kW
390
530
720
950
1250
a
mm
1350
1850
1800
1600
2100
9.4 Water connection
Heating connections
Existing systems
Before connecting the boiler to an existing heating system, flush the
system thoroughly to remove dirt and sludge residues.
Otherwise, this dirt and sludge will be deposited inside the solid fuel
boiler and can lead to local overheating, noise and corrosion. Boiler
damage caused by such deposits is excluded from our warranty.
Where necessary, install dirt traps.
Connections on the water side
On site, ensure that there is a water supply independent of the
power supply. This (redundant) design guarantees that the boiler is
reliably cooled via the thermally activated safety valve in the event of
a power failure. We also refer to the standards and regulations listed
in this document.
Connect all heat consumers and heating circuits to the boiler flow
and boiler return connectors.
Never make any connections to the safety flow or to other connec-
tions.
We recommend you install shut-off valves in the heating flow and
return lines, to avoid having to drain the entire water content out of
the system if subsequent work is required on the solid fuel boiler or
the heating circuits.
Straightforward installation
For safety temperatures up to 110 °C, the boiler requires no inter-
mediate flow piece for the connection of safety equipment.
All the necessary connections, e.g. for water level or pressure limit-
ers, are provided on the boiler.
Boiler circuit and shunt pump
In order to reliably prevent boiler corrosion caused by flue gas con-
densation, the boiler return temperature must never fall below 65 °C.
The boiler has variable output-dependent control. This requires a
constant boiler flow rate of the water to be heated. For this reason,
the boiler circuit with boiler circuit pump and boiler mixer must be
installed in accordance with the design recommendations.
The boiler circuit should be designed in such a way that the temper-
ature differential between flow and return is 15 °C or less. Control of
the boiler circuit pump and valve of the return temperature raising
facility is integrated in the supplied control unit.
System example
General information
■ In order to reliably prevent boiler corrosion caused by flue gas con-
densation, the boiler return temperature must never fall
below 65 °C. A boiler circuit pump with boiler mixer should be pro-
vided in accordance with the system scheme.
■ The boiler circuit should be designed in such a way that the tem-
perature differential between flow and return is 15 K or less.
■ Integrating heat consumers
■ The expansion vessel must be connected to the boiler, without
shut-off devices, via the boiler flow.
Design information
(cont.)
88
Viesmann
VITOFLEX 300-UF
9
5682428
