Calculating The Heat Demand For Dhw Heating For Sports Halls - Viessmann Vitocell 300-H Technical Manual

Sizing
(cont.)
ΔT
(40 °C – 10 °C)
V = V ·
(45°C) (40°C)
ΔT
(45 °C – 10 °C)
30
= 900 · =771 l
35
Suggestion: 2 Vitocell 300-V, each with 300 l capacity with a peak
output of 408 l per cylinder and 816 l as a cylinder bank (DHW tem-
perature 45 °C).
Regarding b)
Required boiler size
As the showering process repeats hourly, the selected cylinder
capacity must be heated up within 1 hour. The heat volume required
to achieve this is calculated as follows:
V · ΔT · c
cyl. A
= Φ =
²
A A
Z
A
600 · 1 · (60 – 10)
=
860 · 1
= 34.9 kW
= Minimum connected load for heating the DHW cyl-
or Φ
²
A A
inder in kW
V = Capacity in litres
cyl
ΔT = Temperature differential between the cylinder stor-
A
age temperature and the cold water inlet tempera-
4
ture
c = Spec. thermal capacity
1 kWh
860 l · K
Z = Heat-up time in h
A

Calculating the heat demand for DHW heating for sports halls

Observe DIN 18032-1, "Sports grounds, sports halls" as a guideline
for the sizing, design and installation of the DHW system.
DHW is drawn-off in sports halls in short bursts.
Therefore, when it comes to selecting suitable DHW cylinders, the
main criterion is the "Peak draw-off rate" (10-minute peak output).
The DHW heating system must be capable of ensuring the DHW
delivery over the entire period of use (throughout the year).
The following values are assumed for sizing the DHW heating
system:
DHW draw-off temperature:
Water consumption per person µ:
Shower duration per person t:
Heat-up time Z :
A
People per heat-up time and training
unit n:
Cylinder storage temperature T
Example for a simple sports hall:
1. Calculating the required DHW volume:
m = t · µ · n
MW
= 4 min/person · 8 l/min · 25 people
= 800 l DHW volume at 40 °C
Selected capacity: 700 l
The selected capacity should roughly correspond to the required
DHW volume.
Peak output from the corresponding tables in the datasheets for the
relevant DHW cylinders.
Conversion to DHW outlet temperature of 40 °C at
VIESMANN
20
Max. 40 °C
8 l/min
4 min
50 min
Min. 25 people
: 60 °C
a
To guarantee adequate heating of the building during winter too, this
heat volume must be added to the heat load. EnEV [Germany] per-
mits this supplement for the following reasons:
1. This is commercial utilisation.
2. There is no output restriction when using a low temperature boiler.
m = Peak output at a DHW outlet temperature of 40 °C
(40 °C)
m = Peak output at a DHW outlet temperature of 45 °C
(45 °C)
(according to table in DHW cylinder datasheet)
45 – 10
m = m ·
(40°C) (45°C)
40 – 10
= 2 · 424 l/10 min
35
= 848 ·
30
= 989 l/10 min
Selected DHW cylinders:
2 x Vitocell 300-H, each with 350 l,
peak output at 70 °C heating water flow temperature = 989 l at 40 °C
DHW heating