Viessmann Vitocell 300-H Technical Manual page 21

Sizing
(cont.)
2. Calculating the required heat-up output for the calculated cyl-
inder capacity:
V · c · (T – T )
a e
= Φ =
²
A A
Z
A
700 · (60 – 10)
= = 49 kW
860 · 0.833
= Heat-up output in kW
or Φ
²
A A
V = Cylinder capacity in l
c = Spec. thermal capacity
1 kWh
860 l · K
T = Cylinder storage temperature in °C
a
T = Cold water inlet temperature in °C
e
DHW heating
Size the boiler and circulation pump for cylinder heating according to
the required heat-up output.
To guarantee adequate heating of the building during winter too, add
this heat amount to the heat load. EnEV [Germany] permits this sup-
plement for the following reasons:
1. This is commercial utilisation.
2. There is no output restriction when using a low temperature boiler.
4
VIESMANN
21