Condensate lifting system (accessory)
C
B
A
Shown on the Vitoladens 333-F
A
Condensate inlet
B
Condensate lifting system
C
Condensate drain
5.4 Hydraulic connection
General
System design
Viessmann condensing boilers can generally be installed in any pum-
ped hot water heating system (sealed system). No special standards
apply.
The circulation pump is an integral part of the appliance.
Minimum system pressure 0.8 bar.
The heating water temperature is limited to 74 ºC.
To minimise distribution losses, we recommend that you size the heat
distribution system to a max. flow temperature of 70 ºC.
Chemical anti-corrosion agents
Corrosion is generally avoided in correctly installed and operated
sealed heating systems.
Never use chemical anti-corrosion agents.
Some manufacturers of plastic pipes recommend the use of chemical
additives. In such cases, only use anti-corrosion agents offered by the
heating trade that have been approved for boilers with DHW heating
via single-walled heat exchangers (instantaneous water heater or
DHW cylinder).
In this, observe VDI guideline 2035 [or local regulations].
Heating circuits
For heating systems with plastic pipes, we recommend the use of
impermeable pipes to prevent the infusion of oxygen through the pipe
walls.
Provide system separation in heating systems with plastic pipes to DIN
4726 that are permeable to oxygen. We supply a separate heat
exchanger for this.
Underfloor heating systems and heating circuits with very large water
content should be connected, even to a condensing boiler, via a three-
way mixer; see technical guide "Control of underfloor heating sys-
tems" or the relevant sample applications.
Install a temperature limiter into the flow of the underfloor heating cir-
cuit to limit the maximum temperature. Observe the requirements of
DIN 18560-2 [or local regulations].
Plastic pipework for radiators
We also recommend the installation of a temperature limiter to restrict
the maximum temperature of plastic pipes in heating circuits with radi-
ators.
Safety valve
A safety valve in accordance with TRD 721 is integrated into the Vito-
ladens (opening pressure 3 bar).
Route the blow-off line in accordance with EN 12828 into a drain outlet
(drain outlet kit available as an accessory). The drain outlet incorpo-
rates a siphon as a stench trap.
Low water indicator
According to EN 12828, special low water level protection can be
omitted for boilers up to 300 kW (except in attic heating centres), as
long as heating can be reliably prevented when the water level is too
low.
The Viessmann Vitoladens are equipped with a low water indicator
(boil-dry protection). Tests have verified that the burner will be auto-
matically switched OFF in the event of water shortage due to a leak in
the heating system and simultaneous burner operation, before the
boiler or flue systems reach unacceptably high temperatures.
Water quality/frost protection
Regarding the quality and volume of heating water, incl. fill and top-up
water, observe VDI Directive 2035.
Water softening measures must be taken if, for example, the specific
system volume exceeds 20 litre/kW output (e.g. installation of a heat-
ing water buffer cylinder).
For recommendations, see the technical guide "Standard values for
water quality".
You may add suitable antifreeze to the heating water in systems that
are not constantly heated and where consequently there is a risk of
frost. For further details, see the VdTÜV datasheet 1466.
Only use fill water of potable quality. Soften fill water harder than
3.0 mol/m
3
.
Design information
(cont.)
54
VIESMANN
VITOLADENS 300-W
/
VITOLADENS 333-F
5
5822 425 GB