Decision-Making Aids For Dhw Heating - Viessmann VITODENS 222-F Technical Manual

Design information
■ 3-way mixer with mixer motor
■ Mixer PCB, capable of communicating with 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
Boiler plinth
Part no. 7352 259

5.2 Decision-making aids for DHW heating

To provide the perfect solution for every situation, the Vitodens can
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 should be taken into consideration when designing
heating systems and deciding between a gas system boiler with inte-
gral DHW loading cylinder or integral DHW cylinder:
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, 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.
VITODENS
(cont.)
3
) and higher, we there-
■ 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 con-
nection
■ 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
5
3 ) upwards.
VIESMANN
55