Viessmann VITOCROSSAL 300 Type CT3 Service Instructions Manual page 28

Water quality requirements
■ In systems > 50 kW, install a water
meter to record the volume of the fill &
top-up water. Enter the volume of the
fill water and the water hardness into
the boiler maintenance checklists.
■ For systems with a specific system vol-
ume in excess of 20 l/kW heating out-
put (apply the output of the smallest
boiler in multi boiler systems), apply
the requirements of the next higher
category of total output (in accordance
with the table). In case of severe
excess (> 50 l/kW), soften the water
down to a total of alkaline earths of ≤
0.02 mol/m 3 .
Operating information:
■ During expansion or repair work, only
drain the necessary pipework sec-
tions.
■ Check, clean and activate all filters,
dirt traps and other blow-down or sep-
arating facilities in the heating water
circuit more frequently after commis-
sioning or recommissioning, and later
on as required, subject to the water
treatment applied (e.g. water soften-
ing).
■ No further steps are required during
commissioning if you fill the heating
system with fully softened water.
If the heating system is filled, not with
fully softened water, but with water
that meets the requirements in the
above table, also observe the follow-
ing during commissioning:
28
(cont.)
■ 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 entire
limescale deposit settling in the heat
transfer area of just one boiler.
■ Where water treatment is required,
treat even the first fill of the heating
systems prior to commissioning. This
also applies to any subsequent filling,
e.g. when adding top-up water, or after
a repair or system expansion.
The build-up of limescale deposits on the
heating surfaces will be minimised if
these instructions are observed.
Any limescale deposits that have formed
because the requirements to VDI Direc-
tive 2035 have not been observed will in
most cases already have caused a
reduction in the service life of the instal-
led heating equipment.
Removing the limescale deposits is one
option for restoring operational viability.
This measure must be carried out by a
specialist. Inspect the heating system for
possible damage prior to returning it into
use.
It is essential that the faulty operating
parameters are corrected to prevent
renewed formation of excessive scale
deposits.