Kilowatts explained

Power output

kilowatts explained

The difference between a kilowatt (kW) and a kilowatt-hour (kWh)

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Knowing the difference between a kilowatt (kW) and a kilowatt-hour (kWh) is necessary to understand power and energy use. These terms are not restricted to heat pumps; sizes of boilers, storage heaters, room heaters and other systems are also described in kW.

Kilowatt (kW) - A Measure of Power

Kilowatt-hour (kWh) - A Measure of Energy

A kilowatt-hour (kWh) is a unit of energy. It may refer to energy used (e.g. by an electrical appliance) or energy produced (e.g. by a heat pump).

A kilowatt (kW) is a unit of power, representing the rate at which energy is used or produced per second.

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Simple Analogy:

Kilowatts (kW) = Kilowatt-hours (kwh) =

Speed of a car (e.g., driving at 60 mph). Distance travelled over time (e.g., driving at 60 mph for 2 hours means you travel 120 miles).

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Kilowatt-hour (kWh) – A Measure of Energy It is the product of the device’s power and the time over which it is operating.

• If a 1 kW electrical appliance runs for one hour, it consumes 1 kWh of energy.

• If a 10 kW output heat pump runs at full capacity for two hours, it produces 20 kWh of heat energy (10 kW × 2 hours = 20 kWh).

Kilowatt (kW) – A Measure of Power The higher the kW of a device such as a heat pump or boiler, the more heat energy is produced over a period of time.A kilowatt is 1000 watts (W).

• Think of kilowatts like the engine size of a car—it tells you how powerful the system is.

• For example, a 10 kW heat pump can provide 10 kilowatts of heating or cooling power at any instant.