When installing a new industrial electric boiler or replacing an existing boiler rated in HP, it is common to convert this unit to kilowatts (kW).
This simple, approximate formula allows you to quickly convert between the two units:
Power (kW) = Power (hp) x 10
Conversion Factor
The exact method for converting HP to kW involves an intermediate conversion to BTU/hr and then converting kW to BTU/hr:
1 hp = 33,475 BTU/hr
1 kW = 3412.142 BTU/hr
Then: 1 hp = 9.81 kW
Difference Between Input and Output Energy for an Electric Boiler
However, as explained in the technical bulletin on converting hp to lb/hr, the HP of a boiler refers to the output energy, while for an electric boiler, kW refers to the input energy.
To convert from one to the other, you must consider the energy efficiency of the electric boiler. Electric boilers do not suffer efficiency losses due to combustion gases, but they do experience losses from radiation and the heat emitted by their electric panels. These losses are very minimal, and many manufacturers simply ignore them.
Efficiency of an Electric Boiler
At full load, the efficiency of an electric boiler is typically estimated at 98%. Therefore, the conversion factor of 1 hp = 10 kW can be used to determine the boiler’s input capacity, or the power demanded from the electrical grid.
Power input (kW) = Power output (hp) x 10 (kW/hp)