24kW is basically the peak when it's doing instant hot-water for the taps. You shouldn't need that to heat a home.
You're right, it can't match the _peak_ output, but the whole system is designed so this isn't necessary.
With a "traditional" combi-boiler, it will turn on occasionally to heat the water in the central heating system, and continue to pump it around. When you need hot water, it switches over the heat-exchanger to directly heat the incoming water and this is when it will ramp up and burn the most gas (24kW+).
For an air-to-water heat pump system, the system will be on almost continually, but will heat the water to a lower temperature, the peak power output is less, but it averages out the same. For hot water, the system will heat a storage cylinder.
One of the catches here is that's it not always an easy retrofit as the lower water temperature can necessitate larger radiators.
You're right, it can't match the _peak_ output, but the whole system is designed so this isn't necessary.
With a "traditional" combi-boiler, it will turn on occasionally to heat the water in the central heating system, and continue to pump it around. When you need hot water, it switches over the heat-exchanger to directly heat the incoming water and this is when it will ramp up and burn the most gas (24kW+).
For an air-to-water heat pump system, the system will be on almost continually, but will heat the water to a lower temperature, the peak power output is less, but it averages out the same. For hot water, the system will heat a storage cylinder.
One of the catches here is that's it not always an easy retrofit as the lower water temperature can necessitate larger radiators.