Pump-Controlled Pressure Maintaining Systems; Water Connection; Heating Connections; Boiler Circuit And Shunt Pumps - Viessmann VITOPLEX 200 Type SX2A Technical Manual

Design information
(cont.)

Pump-controlled pressure maintaining systems

In heating systems with automatic and in particular pump-controlled
pressure maintaining systems with integral deaerating, we recom-
mend the installation of a diaphragm expansion vessel (DEV) for each
boiler as individual protection.
Boiler output Diaphragm expansion vessel
in kW Capacity in litres
up to 300
up to 500
up to 1000
up to 2000
up to 5000
up to 10000

10.3 Water connection

Heating connections

Existing systems
Flush the heating system thoroughly before connecting the boiler to
an existing heating system, to remove dirt and sludge residues.
Otherwise, these dirt and sludge residues will be deposited in the boiler
and can lead to local overheating, noise and corrosion. Boiler damage
caused by such deposits is excluded from our warranty. Where nec-
essary, install dirt traps.
Connections on the heating water side
Connect all heat consumers or heating circuits to the boiler flow and
return connectors. Never make any connections to the safety flow or
to other connections.
We recommend you install shut-off valves into the heating flow and
return lines, so that the entire water content will not have to be drained,
should work be required on the boiler or heating circuits.
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
to (DIN 4726) which are permeable to oxygen. We supply a separate
heat exchanger for this.

Boiler circuit and shunt pumps

The Vitoplex boilers, Vitorond 200, type VD2A and the Vitoradial 300-
T require no boiler circuit pumps for forced circulation. The
Vitorond 200, type VD2A from 125 to 270 kW, the Vitoplex 300 from
90 to 2000 kW and the Vitoplex 200 from 90 to 560 kW with Therm-
Control generally also require no return temperature raising facility.
For more detailed information, see the sample applications.
A shunt pump has proven appropriate for those boilers or individual
cases where a return temperature raising facility is required. The large
water content and the low internal pressure drop of the Vitoplex boilers
enable the system to operate with just a pump for raising the return
temperature (shunt pump), which should be sized to approx. 30 % of
the total flow volume.
The shunt pump will only be activated when the actual temperature
falls below the minimum return temperature.

System accessories

Divicon heating circuit distributor
Pre-assembled heating circuit distributor for connecting up to 4 heating
circuits to the Vitoplex up to 300 kW, the Vitorond up to 270 kW and
the Vitoradial 300-T in single boiler systems.
To be positioned on the l.h. or r.h. side of the boiler or in conjunction
with wall mounting brackets, on the wall.
OIL/GAS BOILERS
This reduces the frequency and level of pressure fluctuations. This
contributes considerably to improved operational reliability and longer
service life of the system components.
Damage to the boiler or to other system components may result if
these recommendations are not followed.
Also ensure that only corrosion-technically sealed PDH systems are
used, which are protected against oxygen ingress into the heating
water. Otherwise damage to the system through oxygen corrosion can
50
result.
80
PDH systems with atmospheric deaerating through cyclical pressure
140
release create a central post-ventilation of the heating system, but
300
represent no oxygen removal in the sense of corrosion protection to
800
VDI 2035 sheet 2.
1600
Underfloor heating systems and heating circuits with a large water
content should also be connected via mixers, if low temperature and
ultra-low temperature boilers are used. These should be controlled via
the Vitotronic 300 (type GW2), Vitotronic 300-K or with a separate
control unit, e.g. the Vitotronic 200-H.
Easy installation
For safety temperatures up to 110 ºC, the Vitoplex boilers require no
intermediate flow piece, that is costly and difficult to install, for the
connection of safety equipment.
All connections required for the various pieces of equipment, e.g. for
water level or pressure limiters, are provided on the boiler.
Resulting advantages are:
■ Smaller pumps, i.e. reduced investment
■ Lower power consumption of the pump
■ The shunt pump runs for shorter periods
■ Reduced electricity bills
Information regarding the heating circuit pumps
Heating circuit pumps in heating systems with rated output > 25 kW
must be equipped or designed in such a way, that the power con-
sumption will be matched automatically to the operational delivery
demand in at least three stages, if no safety concerns relating to the
boiler make demands to the contrary.
For the Vitorond, provide the Divicon pipe connections on site. See
Divicon heating circuit distributor from page 19.
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VIESMANN
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