Viessmann Vitocell 300-H Technical Manual page 16

Sizing
(cont.)
Σ(n · p · v · w )
v
N =
3.5 · 5820
Σ(n · p · v · w )
v
=
20370
n = Number of similar residential units
p = Occupancy factor per similar residential unit
v = Number of similar draw-off points per similar residential unit
w = Draw-off demand in Wh
v
(n · p · v · w ) must be calculated for each relevant draw-off point per
v
similar residential unit.
Now use the calculated demand factor N to select the required DHW
cylinder at the appropriate heating water flow temperature from the
tables on pages 8 and 11. Select a DHW cylinder with an N
least equal to N.
Table 5
No. of residen- Room factor
tial units
n r
4
10
4
2
4
5
Form for calculating the heat demand for DHW heating in residential buildings
Calculating the demand of residential units with centralised supply
systems
Calculating the demand factor N for determining the required DHW cylinder size
Project
Occupancy factor p based on statistical values as per table 5, page 16
1 2
Sequential Room fac-
number of tor
residential
unit r
groups
1 1.5
2 3.0
3 4.0
4 4.0
VIESMANN
16
Occupancy Amenities in the residential unit
factor
p Number, description
1.5 2.0 1 shower cubicle with standard shower
head
1 washbasin in the bathroom
1 sink in the kitchen
3 2.7 1 bath 140 l
1 washbasin in the bathroom
1 sink in the kitchen
4 3.5 1 shower cubicle with mixer tap and de-
luxe shower head
1 shower cubicle with standard shower
head (in a physically separate location)
1 washbasin in the bathroom
1 sink in the kitchen
4 3.5 1 bath 160 l
1 shower cubicle with deluxe shower
head in a separate room
1 washbasin in the bathroom
1 bidet
1 sink in the kitchen
5 4.3 1 bath 160 l
1 washbasin in the bathroom
1 bidet
1 bath 140 l, in the guest room
1 washbasin in the guest room
1 sink in the kitchen
3 4 5
No. of resi- Occupancy
dential factor
units
n p n · p
4 2.0 8.0
10 2.7 27.0
2 3.5 7.0
4 3.5 4.0
The demand factor N is identical to the number of standard residen-
tial units in the building project.
It does not necessarily correspond to the actual number of residen-
tial units.
Example:
For a residential building project, design the DHW system on the
basis of demand factor N.
The numbers of similar residential units, the room factor and the
equipment level listed in table 5 have been taken from the building
plans.
The occupancy factor p was determined using the room factor r and
table 1 on page 14.
The number of draw-off points to be used in the design was calcula-
ted using table 2 on page 14 and table 3 on page 15.
factor at
L
Project no:
Part no:
6 7 8
No. of draw-off points to consider
(per residential unit)
No. of Short Draw-off
draw-off code demand
points w
v
v
in Wh
1 NB1
1 NB1
1 BRL
1 BRN
1 NB2
1 BRL
Apply for the demand calculation
No. of draw-off points, description
As per table 2 on page 14
1 shower cubicle (BRN)
As per table 2 on page 14
1 bath (NB1)
As per table 3 on page 15
1 shower cubicle (BRL)
As per table 3 on page 15
1 bath (NB2)
1 shower cubicle (BRL)
As per table 3 on page 15
1 bath (NB2)
1 bath (NB1) with 50 % of the draw-off
demand w
v
1 washbasin (WT)
1 bidet (BD)
9 10
v · w n · p · v · w
v v
in Wh in Wh
5820 5820 46560 NB1 for
5820 5820 157140
7320 7320 51240
3660 3660 25620
6510 6510 91140
7320 7320 102480
11
Comments
BRN
DHW heating