Froling SP Dual compact Operating Instructions Manual page 25

Operating the system
Heating up the boiler
Operating Instructions SP Dual compact | B1500016_en
As the medium to be heated is water and the mass is roughly the same as the volume (2000
litres = 2000 kg), we can use the simplified formula Q = m x c x Δt.
Q = energy required
m = mass of the medium to be heated
c = heat capacity of the medium to be heated (constant for water)
Δt = temperature difference between start and end temperature
Mass (m) x heat capacity (c) x temperature difference (Δt) = energy (Q)
2000 kg x 1.163 Wh/kgK x 30 K = 69 780 Wh
Heating a 2000 litre storage tank from 50°C to 80°C requires approx. 69.8 kWh of energy.
1. Temperature difference in Kelvins (K). As these are not absolute temperatures the value can be entered in degrees Celsius (°C). (30°C
equals 30°K)
The amount of fuel can now be calculated from the energy required:
For our sample calculation we used beech with a water content w=20%. The energy content
of the fuel varies according to the type of wood and the water content.
[page 26])
Energy required = 69.8 kWh (from calculation above)
Energy content of fuel = 3.8 kWh/kg (beech, w=20%)
Energy required / energy content of fuel = amount of fuel
Approx. 18.4 kg beech wood (w=20%) is required to heat a 2000 litre storage tank from 50
°C to 80 °C.
69 780 Wh = 69.8 kWh
69.8 kWh / 3.8 kWh/kg = 18.4 kg
3
1)
(⇨ See "Fuel table"
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