General Design Information; Safety Heat Exchanger With Thermally Activated Boiler Protection; Heating By The Heating Water Buffer Cylinders; Sizing The Heating Water Buffer Cylinder - Viessmann VITOLIGNO 200-S Technical Manual

Design information

General design information

■ When connecting several heating circuits, the total of the drawn heat
should not exceed the rated boiler heating output. Line regulating
valves may be installed to enable improved adjustment of the sys-
tem. The estimated and actual heat loads are frequently far apart,
because of a lack of thermal building insulation (new build, not yet
rendered/plastered, etc.).
■ All systems require a return temperature raising facility, a heating
water buffer cylinder and a weather-compensated heating circuit
control unit with 3-way mixer or 4-way mixer (min. boiler water tem-
perature 60 ºC).

Safety heat exchanger with thermally activated boiler protection

C
A
B
A Cold water inlet R ¾ for thermally activated safety valve
B DHW outlet R ¾ for thermally activated safety valve
C Sensor for thermally activated safety valve
D Thermally activated safety valve
The safety heat exchanger is factory-fitted and is designed to prevent
overheating if the DHW circulation is interrupted (e.g. during power
failure). Never use these for DHW heating.
Connect the thermally activated safety valve according to EN 12828
with an unrestricted drain to the heat exchanger. This connection must
not be fitted with a manual shut-off device.

Heating by the heating water buffer cylinders

If the boiler flow temperature falls below the set system temperature,
then the heating for the heating circuit or DHW heating is drawn from
the heating water buffer cylinders. For this, observe the function of the
buffer cylinder control valve (see "System examples" in the technical
guide).

Sizing the heating water buffer cylinder

The heating water buffer cylinder ensures rapid heating in the morning
and adequate heat transfer under all operating conditions.
Calculate the required content of the heating water buffer cylinder
using the following formula (design basis is EN 303-5):
V = 15 x T x Q x 1 – 0.3 x
cyl. B N
VITOLIGNO 200-S
(cont.)
D E
F G H
Q
H
Q
min
E Cleaning aperture
F Drinking water filter
G Non-return valve
H Pressure reducing valve
After the installation, the thermally activated safety valve and the
cleaning aperture should still be freely accessible.
Minimum supply pressure
Safety heat exchanger:
Permiss. operating pressure:
V Heating water buffer cylinder content in l
cyl.
T Combustion duration at
B
rated heating output in h
Q Rated boiler heating output in kW
N
Q Heat load of the building in kW
H
Q Lowest boiler heating output in kW
min
6
3 - 6 bar
6 bar
VIESMANN
73