Information On Water Quality; Separate Dhw Cylinders; Sizing The Dhw Cylinder - Viessmann VITODENS 111-W Technical Manual

Design information

Information on water quality

During DHW heating, settling of lime on the surfaces of the plate
heat exchanger cannot be completely prevented. The tendency
towards limescale build-up depends on various conditions, predomi-
nantly on the substances contained in the water, the amount of water
that is heated (DHW consumption) and the DHW temperature.
Although scale deposits inside the plate heat exchanger are gener-
ally minor enough not to cause any reduction in DHW output, such
impairment cannot be excluded with increased water hardness.
From a water hardness of 20 °dH (3.5 mol/m
fore recommend the use of DHW cylinders with internal indirect coils
or a water treatment system in the cold water supply when heating
DHW.
Selection table
DHW demand, con- DHW supply for one apartment
venience
DHW supply for a detached house
Centralised DHW supply for an apartment building
Decentralised DHW supply for an apartment building
Use of the various One draw-off point
connected draw-off
Several draw-off points, not used simultaneously
points
Several draw-off points, used simultaneously
Distance of draw-off Up to 7 m (without DHW circulation pipe)
point from boiler
With DHW circulation pipe
Modernisation Existing DHW cylinder
Replacement of an existing combi boiler
Footprint Low space requirement (siting in a recess)
Sufficient space available (installation room)
Solar DHW heating Connection to a dual mode DHW cylinder
can be connected
Connection to the integral DHW cylinder
+ = Recommended
0 = Recommended under certain conditions
– = Not recommended

Separate DHW cylinders

For greater DHW convenience, separate DHW cylinders are also
available in white in the following versions:
■ Below the boiler (120 or 150 l)
■ Adjacent (160, 200 or 300 l)
Further DHW cylinders with up to 1000 l capacity are offered in Vito-
silver and may also be used in accordance with the available heating
output.

Sizing the DHW cylinder

Determine the DHW cylinder size in accordance with the specific
DHW demand.
Various consumer combinations may apply.
If identical consumers are combined, only take into account the indi-
vidual consumer, not the combination.
The following summary enables an approximate sizing of the DHW
cylinder:
VITODENS
(cont.)
3
) and higher, we there-
Please note that regional water supply utilities frequently specify an
average water hardness. Higher levels of water hardness may there-
fore occur from time to time. This may make the use of a water treat-
ment facility advisable even from 17 °dH (> 3.0 mol/m
Vitodens 100-W
Gas condensing Gas condensing
combi boiler with boiler with sepa-
instantaneous rate DHW cylin-
water heater der
+ +
0 +
– +
+ +
+ 0
+ +
– +
+ +
– +
– +
+ –
+ 0
+ +
– +
– –
The Vitodens 100-W as gas condensing boilers are equipped at fac-
tory with a separate DHW cylinder for DHW heating. For this pur-
pose, the Vitodens 100-W is provided with an integral diverter valve.
To connect a separate DHW cylinder, always include the connection
set for the respective DHW cylinder in your order.
For DHW cylinder specifications, see chapter "DHW cylinders".
Small households (1 to 2 occupants)
Average households (3 to 4 occupants)
Note
Instead of a Vitodens 100-W with 120 l DHW cylinder, a
Vitodens 111-W can also be used.
3 ) upwards.
Vitodens 111-W
With integral DHW
loading cylinder
+
+
–
0
0
+
+
+
–
–
0
0
+
–
–
6
VIESMANN
49