Viessmann Vitocrossal 300 CA3 2.5 Installation And Service Instructions Manual page 119

Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Checking the Water Conditions
(continued)
The standard values assume the following:
The total volume of fill and top-up water during its
service life will not exceed three times the water content
of the heating system.
The specific system volume is less than 1.5 USG/MBH
(20 L/kW) heating output. In multiboiler systems, apply
the output of the smallest boiler.
Soften the fill and top-up water in heating systems operating
under the following conditions:
The total of alkaline earths in the fill and top-up water
exceeds the standard value.
Higher fill and top-up water volumes are expected.
The specific system volume is higher than 1.5 USG/
MBH (20 L/kW) heating output. In multiboiler systems,
apply the output of the smallest boiler.
In systems > 170 MBH (50 kW), install a water
meter to capture the amount of fill and top-up water.
Enter the volume of fill water and the water hardness
into the boiler maintenance checklists.
For systems with a specific system volume greater
than 1.5 USG/MBH (20 L/kW) heating output, apply
the requirements of the next higher category of total
heating output (in accordance with the table).
In multiple boiler systems, the output of the smallest
boiler is used. In the case of severe overshoot >3.8
USG/MBH (> 50 L/kW), soften the water down to a
total of alkaline earths of≤ 2 ppm of CaCO
Operating information:
During expansion or repair work, only drain the
pipework sections which are crucial.
Check, clean and activate filters, dirt traps and other
blow-down or separating facilities in the heating
water circuit frequently after commissioning and in
new installations. Thereafter check and maintain as
required, depending on the type of water treatment
applied (e.g. water softening).
If the heating system is filled with fully softened
water, no other measures for start-up are required.
If the heating system is not filled with fully softened
waterbut with water which fulfils the requirements
given in the table above, the following should also
be considered for commissioning:
Start the system step by step with a high heating
water flow rate, starting with the lowest boiler
output. This prevents localized concentration of lime
scale deposits on the boiler heating surfaces.
In multiple boiler systems, start all boilers simultaneously
to prevent the entire lime scale deposit settling in the
heat exchanger of just one boiler.
Where water treatment is required, treat the first fill
of the heating system prior to start-up. This also
applies to any subsequent filling, e.g. when adding
top-up water or after a repair, or for any system
expansion.
The build-up of lime scale deposits on the heating
surfaces will be minimised if these instructions are
followed.
Service
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