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Hot water heating efficiency and CoP explained

The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or airconditioning system is a ratio of useful heating or cooling provided to work required.

For example a CoP of 4.7 means that for every unit of electricity the Reclaim hot water system uses it returns 4.7 units of heat energy to the cylinder. That’s with an ambient air temperature of only 19°C.

The equation used is: C O P = Q /W  


  • Q   is the useful heat supplied or removed by the considered system.
  • is the work required by the considered system.

As the air temperature rises (work decreases), the CoP goes to a maximum of 6 at 32°C. Conversely, the CoP drops with a corresponding drop in temperature (work increases), down to 2.4 at -10°C. That’s still over two times more heat energy out compared to electrical energy in – even in freezing weather.

The reason the Reclaim hot water systems results compare so well is due to the cutting-edge technology inside the system and because it uses CO2 as the refrigerant.

This split water heating system works by combining a compressor, fan and pump – operated by a smart controller connected to your hot water cylinder. Cold water is fed from the cylinder into the compressor, which is housed outside, where it is heated to 63°C before being returned to the top of the hot water cylinder.