Boiler Supplement Z - Viessmann Vitocell 100-H Technical Manual

Sizing
(cont.)
Calculating the demand of residential units with centralised supply
systems
Σ n = 25
i
Σ(n · p · v · w ) 676710
v
N = =
3.5 · 5820 20370
With the aid of the calculated demand factor N = 33.2, the tables in the
relevant datasheets enable the selection of the required DHW cylinder
at the available heating water flow temperature (z. B. 80 ºC) and a
cylinder storage temperature of 60 ºC:
For this, select a DHW cylinder with an N
calculated demand factor N.
Note
The performance factor N
■ Flow temperature
■ Storage temperature
■ Available or transferable output
For deviating operating conditions, modify the performance factor N
from the values shown in the tables in the relevant datasheets.

Boiler supplement Z

According to DIN 4708-2 and VDI 3815, the rated heating output of a
boiler must be increased by the boiler supplement Z
4
heating demand (see table 6).
Observe the explanations in DIN/VDI [or local regulations].
DIN 4708 specifies three main demands for the rated heating out-
put of the heat source:
Demand 1
The performance factor must be at least equal to or greater than the
demand factor:
N ≥ N
L
Demand 2
Only if the rated boiler heating output ²
equal to the continuous output can the DHW cylinder deliver the per-
formance factor N stated by the manufacturer:
L
≥ ² or Φ ≥ Φ
²
K D K D
Demand 3
Heat generating systems used for both DHW and central heating must
cover the additional output Z
as the standard heat load Φ
DIN 4701):
Φ ≥ Φ + Z
K HL buil. K
On the basis of DIN 4708-2, VDI 3815 is used for calculating a sup-
plement to the rated boiler heating output as a function of the demand
factor N and a minimum cylinder capacity (see table 6).
It has proved successful in practice to take the boiler supplement into
account according to the following relations:
Φ ≥ Φ · ϕ + Z
K HL buil. K
ϕ = Factor for the capacity utilisation of the building heating system (all
rooms heated)
Number of residential units per building
up to 20
21 to 50
> 50
VIESMANN
16
= 33.2
factor at least equal to the
L
varies subject to the following variables:
L
K
to cover the DHW
K
or Φ is higher or at least
K K
for heating systems in buildings, as well
K
calculated to EN 12831 (previously
HL buil.
ϕ
1
0.9
0.8
Project no:
Sheet no:
Σ (n · p · v · w ) = 676,710 Wh
v
Possible DHW cylinders:
■ From selection diagram from page 10 and the Vitocell 300-H data-
sheet:
Vitocell 300-H with 700 l capacity (N
prising 2 × Vitocell 300-H, each with 350 l capacity
■ From selection diagram from page 10 and the Vitocell 300-V data-
sheet:
Vitocell 300-V with 600 l capacity (N
prising 2 × Vitocell 300-V, each with 300 l capacity
Selected DHW cylinder:
2 × Vitocell 300-V, each with 300 l capacity.
L
Table 6 – Boiler supplement Z
Demand factor N
1
2
3
4
5
6
7
8
9
10
12
14
16
18
20
22
24
26
28
30
40
50
60
80
100
120
150
200
240
300
Note
In buildings with an extremely low heat load Φ
carried out to determine whether the output of the heat source, includ-
ing supplement Z , is sufficient for the selected performance factor. It
K
may be necessary to select a larger DHW cylinder.
= 35) as cylinder bank com-
L
= 38) as cylinder bank com-
L
K
Boiler supplement Z
K
in kW
3.1
4.7
6.2
7.7
8.9
10.2
11.4
12.6
13.8
15.1
17.3
19.5
21.7
23.9
26.1
28.2
30.4
32.4
34.6
36.6
46.7
56.7
66.6
85.9
104.9
124.0
152.0
198.4
235.2
290.0
, a check must be
HL buil.
DHW heating