Expansion Vessels - Viessmann VITODENS 200-W Type B2HA Technical Manual

Design information
■ Flush the heating system thoroughly before filling.
■ Only fill with water of potable quality.
■ Fill and top-up water with a water hardness in excess of the follow-
ing values must be softened, e.g. with the small softening system
for heating water (see the Viessmann Vitoset pricelist):
Total permissible hardness of the fill and top-up water
Total heating Specific system volume
output
kW < 20 l/kW
≤ 50
≤ 3.0 mol/m 3
(16.8 °dH)
> 50 to ≤ 200 3
≤ 2.0 mol/m
(11.2 °dH)
> 200 to 3
≤ 1.5 mol/m
≤ 600
(8.4 °dH)
> 600
< 0.02 mol/m 3
(0.11 °dH)
■ For systems with a specific system volume in excess of 20 l/kW
heating output, use the output of the smallest boiler in multi boiler
systems.
■ Special antifreeze suitable for heating systems can be added to
the fill water. The antifreeze manufacturer must verify its suitability,
since otherwise damage to gaskets and diaphragms can occur as
well as noisy heating operation. Viessmann accepts no liability for
any resulting damage or consequential losses.
When designing the system, observe the following:
■ Install shut-off valves in each section. This prevents the need for
draining all the heating water in the case of repairs or system
expansion.
■ In systems > 50 kW, install a water meter to record the volume of
fill and top-up water. Record the amount of water added to the sys-
tem and the water hardness.
Operating information:
■ Commission the system step by step, starting with the lowest
boiler output and a high heating water flow rate. This prevents
localised concentration of limescale deposits on the boiler heating
surfaces.
■ In multi boiler systems, start all boilers simultaneously to prevent
the total amount of limescale deposits settling in the heat
exchanger of just one boiler.
■ During expansion or repair work, only drain the necessary pipe-
work sections.
■ Where water treatment is required, treat even the first fill of the
heating system prior to commissioning. This also applies to any
subsequent filling, e.g. when adding top-up water or after a repair,
or for any system expansion.
■ Check, clean and activate filters, dirt traps and other blow-down or
separating facilities in the heating water circuit more frequently
after commissioning and in new installations. Later on this can be
carried out subject to the requirements of the water treatment
applied (e.g. water softening).
DHW heating
When operating a DHW cylinder, ensure that the heating output of
the heat generator can be transferred to the DHW cylinder as contin-
uously as possible. In borderline situations, we recommend operat-
ing the DHW cylinder in parallel mode with the heating circuit pump
and circulation pump for cylinder heating (no cylinder priority).

Expansion vessels

In accordance with EN 12828, water heating systems must be equip-
ped with a pressure expansion vessel.
VITODENS 200-W
(cont.)
≥ 20 l/kW to ≥ 50 l/kW
< 50 l/kW
≤ 2.0 mol/m 3 < 0.02 mol/m
(11.2 °dH) (0.11 °dH)
3
≤ 1.5 mol/m < 0.02 mol/m
(8.4 °dH) (0.11 °dH)
3
≤ 0.02 mol/m < 0.02 mol/m
(0.11 °dH) (0.11 °dH)
< 0.02 mol/m 3 < 0.02 mol/m
(0.11 °dH) (0.11 °dH)
By using the DHW cylinder connection set (accessories) the DHW
cylinder can be connected upstream of the low loss header in combi-
nation with the heating circuit connection set with integral low loss
header. Provide a venting facility on the heating water flow or return
of the DHW cylinder during installation.
3
3
3
3
If the cylinder capacity is below the following values, we recommend
connecting the DHW cylinder downstream of the low loss header in
the secondary side of the heating system.
Rated boiler heating output
49 to 80 kW
99 kW
120 and 150 kW
Always connect the DHW cylinder on the same side as the heating
circuits. A connection on the opposite side is not permissible.
In conjunction with multi boiler systems, the DHW cylinder must be
connected downstream of the low loss header on the secondary side
of the heating system.
Installation examples
For installation examples for the Vitodens 200-W: See
www.viessmann-schemen.com.
The size of the expansion vessel to be installed is subject to the
heating system specification and should be checked in each case.
DHW cylinder capacity
< 350 l
< 400 l
< 500 l
VIESMANN
75
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