Hydraulic Connection; General Information - Viessmann VITODENS 242-F Technical Manual

Design information
Condensate lifting system (accessories)
A
A Condensate inlet
B Condensate lifting system
C Condensate drain

6.5 Hydraulic connection

General information

System design
Viessmann condensing boilers can generally be installed in any fully
pumped hot water heating system (sealed unvented system).
The circulation pump is an integral part of the Vitodens.
Minimum system pressure 1.0 bar (0.1 MPa).
The boiler water temperature is limited to 82 °C.
To minimise distribution losses, we recommend sizing the heat distri-
bution system to a max. flow temperature of 70 °C.
For apartments with less than 80 m
houses with low heat demand we recommend, due to the immediate
capturing of the room-influencing factors, using the Vitodens with a
constant temperature control unit in conjunction with the Vitotrol 100.
Chemical anti-corrosion agents
In correctly installed and operated sealed unvented heating systems
corrosion is generally avoided.
Never use chemical anti-corrosion additives.
Some manufacturers of plastic pipes recommend the use of chemical
additives. In such cases, only use anti-corrosion additives offered by
the heating trade that have been approved for boilers with DHW heat-
ing via single-walled heat exchangers (instantaneous water heater or
DHW cylinder).
For this, observe the VDI guideline 2035 [or local regulations].
Heating circuits
For heating systems with plastic pipes, we recommend the use of
impermeable pipes to prevent the diffusion of oxygen through the pipe
walls.
Provide system separation in heating systems with plastic pipes that
are permeable to oxygen (DIN 4726). A separate heat exchanger for
this purpose is available.
Install a dirt separator in underfloor heating systems. See Viessmann
Vitoset pricelist.
Underfloor heating systems and heating circuits with very large water
content (>15 l/kW) should be connected to the condensing boiler via
a 3-way mixer. See technical guide "Control of underfloor heating sys-
tems" or the relevant sample applications.
Install a temperature limiter in the flow of the underfloor heating circuit
to restrict the maximum temperature. Observe the requirements of
DIN 18560-2 [or local regulations].
VITODENS
(cont.)
C
B
2 living space or for low energy
Plastic pipework for radiators
We also recommend the use of a temperature limiter to restrict the
maximum temperature for plastic pipework in heating circuits with radi-
ators.
Attic heating centre
The installation of a low water indicator, compulsory according to the
DVGW [Germany], is not required when installing boilers in an attic
heating centre.
The boilers are protected against water shortage in accordance with
EN 12828.
Safety valve
A safety valve in accordance with TRD 721 is integrated in the
Viessmann condensing boiler (opening pressure 3 bar (0.3 MPa)).
Low water indicator
According to EN 12828, a low water indicator can be omitted for boilers
up to 300 kW, as long as heating can be reliably prevented when there
is a water shortage.
Viessmann condensing boilers 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 the flue system reaches unacceptably high temperatures.
Water quality/frost protection
Unsuitable fill and top-up water increases the level of deposits and
corrosion and may lead to the boiler damage.
Observe VDI 2035 regarding quality and amount of heating water,
including fill and top-up water.
■ Flush the heating system thoroughly before filling.
■ Only fill with water of potable quality.
6
VIESMANN
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