General Formulas For Calculating The Cylinder Loading System; Sample Calculation - Viessmann Vitocell 100-H Technical Manual
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Cylinder loading systems — Vitocell 100-L with Vitotrans 222
A
O
B
C
P
A DHW
B Hot water inlet from the heat exchanger
C Heating lance
D Plate heat exchanger
E Air vent valve
F Heating water flow from the heat pump
G Heating water return to the heat pump
H Heat pump
5.3 General formulas for calculating the cylinder loading system
With reference to EN 12831, Q = Φ is used for heat volume and
² = L for heating output (continuous output) instead of the values cur-
rently used by DIN 4701 .
Calculation based on water volume
L · t
V
=
in l
D
c · ΔT
V
= V
+ V
in l
ttl.
D
cyl.
= n
· ´ · t in l
Z
5.4 Sample calculation
A sports centre is equipped with 16 showers which are limited to
15 l/min.
According to design requirements, 8 showers are operated simulta-
neously for up to 30 min continuously. The drawing temperature
should be 40 ºC. A max. of 100 kW boiler output is available for DHW
heating.
c
= Spec. thermal capacity
1 kWh
860 l · K
n
= Number of DHW cylinders
n
= Number of draw-off points
Z
Φ
= Heat volume in kWh available by continuous out-
D
put
L
= Continuous output in kW
DHW heating
E
E
E
L
M
K
D
N
(cont.)
E
F
M
A
B
AB
G
H
K Line regulating valve
L Non-return valve
M Cylinder primary pump
N Common cold water connection with safety assembly to
DIN 1988
O Vitocell 100-L
P Cylinder temperature sensor of the heat pump
Calculation based on heat volume
Φ
= L · t in kWh
D
Φ
= V
· ΔT · c in kWh
ttl.
ttl.
= Φ
+ Φ
in kWh
cyl.
D
= V
· ΔT · c = Φ
+ Φ
ttl.
cyl.
D
Φ
= V
· c · (T
– T
) in kWh
cyl.
cyl.
a
e
Φ
= Total heat demand in kWh (for production and de-
ttl.
mand)
Φ
= Useable heat volume of the total cylinder capacity
cyl.
in kWh
Φ
= Useable heat volume of a single DHW cylinder in
cyl. ind.
kWh
t
= Time in h
T
= Cylinder storage temperature in ºC
a
T
= Cold water inlet temperature in ºC
e
ΔT
= Temperature differential between draw-off temper-
ature and cold water inlet temperature in K
= Draw-off rate per draw-off point in l/h
´
V
= DHW heated by continuous output in l
D
V
= Total draw-off volume in l
ttl
V
= Useable cylinder capacity in l
cyl
5
VIESMANN
27
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