Expansion Vessels - Viessmann VITODENS 222-F Series Technical Manual

Design information
Route the discharge pipe in accordance with EN 12828 into a drain
outlet (drain outlet kit available as an accessory). The drain outlet
incorporates a siphon as a stench trap.
Low water indicator
According to EN 12828, a low water indicator can be omitted for boil-
ers 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 indica-
tor (boil-dry protection). Tests have verified that the burner will be
automatically 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 tem-
peratures.
Water quality/frost protection
Unsuitable fill and top-up water increases the level of deposits and
corrosion and may lead to boiler damage.
Observe VDI guideline 2035 regarding the quality and volume of
heating water, incl. fill and top-up water.
CH: Observe SWKI guideline BT 102-01.
■ Flush the heating system thoroughly before filling.
■ Only fill with water of potable quality.
■ VDI guideline 2035 recommends water softening treatment to pre-
vent harmful scaling in the heating water. Additives to stabilise
hardness do not remove the scale forming chemicals from the
heating water. Fill and top-up water with a water hardness in
excess of the following 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)
■ 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 (category 1 to 3) suitable for heating systems
can be added to the fill water. The use of glycols without sufficient
inhibition and buffering is not permitted. The suitability of the anti-
freeze must be confirmed by the manufacturer. If antifreeze is
added, more monitoring and maintenance is necessary. Observe
the manufacturer's instructions. Viessmann accepts no liability for
damage and malfunctions caused by unsuitable or incorrectly
dosed antifreeze, or incorrect maintenance.

Expansion vessels

In accordance with EN 12828, water heating systems must be equip-
ped with an expansion vessel.
An expansion vessel is integrated in the boilers:
■ Vitodens 200-W and 222-W: Capacity 10 l
■ Vitodens 222-F and 242-F: Capacity 18 l
Pre-charge pressure in the delivered condition: 0.75 bar (0.075 MPa)
Determine the size of the expansion vessel to be installed in accord-
ance with EN 12828.
VITODENS
(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)
■ EN 1717 and DIN 1988-100 must be observed if the heating water
is used simultaneously as a heat transfer medium for DHW heat-
ing.
■ When disposing of heating water that contains additives, check
whether it may be discharged into the public drain network once it
has been treated again.
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 filled into 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 heating surfa-
ces.
■ 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).
Installation examples
For installation examples, see "www.viessmann-schemes.com".
Never install the Vitodens 222-W in dual mode systems with solid
3
fuel boilers.
3
If the integral expansion vessel is insufficient, install a suitably sized
expansion vessel on site.
Note
When hydraulically connecting the diaphragm expansion vessel,
ensure that there is always a connection between the diaphragm
expansion vessel and the heat generator.
For example, when the thermostat valves are closed and if the 3-
way diverter valve is set to "DHW". The 3-way diverter valve is
installed in the heating water flow.
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VIESMANN
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