This formula will help you choosing the best heater for your needs.
Basic formula:
V x ΔT x K = kcal/h
V – is the volume to be heated in m3.
ΔT – is the difference betwen the existing and desired temperature in °C.
K – is the dispersion coefficient (from 0,5 to 3,5)
Key:
V = width 4 m, lenght 12 m, height 3 m, volume to be heated = 144 m³
ΔT = external temperature -5 °C. Needed temperature inside + 18 °C, temperature ΔT = 23°C
K = This factor depands on type of construction and isolation
K = 3,5
Not insulated buildings (wood or corrugated metal buildings, greenhouses)
K = 2,5
Poorly insulated buildings (old houses and cellars).
K = 1,5
Moderately insulated buildings (garages).
K = 0,5
Well insulated buildings (houses and offices).
Example: needed heating power
144 x 23 x 3,5 = 11.592 kcal/h (or 13,5 kW)
(V x ΔT x K = kcal/h)
1 kW / h = 860 kcal / h
You can now choose the heater that best suits your requirements.