Decision-Making Aids For Dhw Heating; Information On Water Quality - Viessmann VITODENS 242-F Technical Manual

Design information
K Solar flow R ¾
L Heating return, heating circuit with mixer R ¾
Note
The adjustable feet give the height measurements of the connections
a tolerance of + 15 mm.
For connecting the on-site gas, heating water and DHW lines in the
wall.
Assembly kit comprising:
■ Plate heat exchanger for system separation of the heating circuit with
mixer
■ Variable speed high efficiency circulation pump for the heating circuit
with mixer
Boiler plinth
Part no. 7352 259

6.2 Decision-making aids for DHW heating

To provide the perfect solution for every situation, the Vitodens may
be supplied with an integral DHW loading cylinder, an integral DHW
cylinder with internal indirect coil or an integral solar cylinder (see
product description).
Various factors must be considered when designing heating systems
and deciding between gas boilers with integral DHW loading cylinders
or integral DHW cylinders:

Information on water quality

Vitodens with loading cylinder:
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, predominantly 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 generally
minor enough not to cause any reduction in DHW output, such impair-
ment cannot be excluded with increased water hardness. From a water
hardness of 20 °dH (3.5 mol/m 3 ) and higher, we therefore recommend
the use of DHW cylinders with internal indirect coils or a water treat-
ment system in the cold water supply when heating DHW.
VITODENS
(cont.)
■ 3-way mixer with mixer motor
■ Mixer PCB, capable of communicating with the Vitotronic 200 via KM
BUS
■ Adjustable bypass
■ Connection set for installation on finished or unfinished walls, with:
– Connection pipes
– Shut-off valves for heating water flow and return, with boiler drain
& fill valve
– 2 connectors for DHW
– 2 connectors for solar flow and return
– Gas shut-off valve (R ½) with thermally activated safety shut-off
valve
■ Flow temperature sensor
■ Cover, designed to match appliance
■ Balanced flue extension, boiler flue connection
■ For siting the appliance on unfinished floors
■ Height adjustable, for screed heights from 10 to 18 cm
■ With spacer for installation on finished walls, for downward connec-
tion
■ DHW demand, convenience
■ Use of the various connected draw-off points
■ Distance of the draw-off points from the boiler
■ System modernisation
■ Space requirement
■ Water quality
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
6
3 ) upwards.
VIESMANN
65