Modulation

Modulation is the control behaviour that lets a heat pump vary its heating output, usually through an inverter-driven or output-dependent compressor, so it can run at partial load when the building needs less heat. In heat pump documents the term may appear as modulating operation, output modulation or modulation range, often shown as a kW range or linked to fewer start-stop cycles. It is not the same as design heat load, rated heating output, weather compensation, a room thermostat setting, a running-cost guarantee or proof that the system is correctly sized or commissioned.