3 ms·

If you do not have temps below 0-5°C that might be true. Below the freezing point efficiency drops quite a bit.

• pedrocr 6y ago
  "Name a source please" :) Keeping 5x over the entire winter includes some pretty cold nights. And ground source systems can improve even this by quite a bit.
  • Haemm0r 6y ago
    Nicely played :) Here we go: https://industrialheatpumps.nl/en/how_it_works/cop_heat_pump/ https://industrialheatpumps.nl/en/how_it_works/cop_heat_pump... or better this pic: https://www.researchgate.net/figure/Performance-map-of-the-heat-pump-showing-the-COP-as-a-function-of-ambient-temperature_fig2_261259472 https://www.researchgate.net/figure/Performance-map-of-the-h...
    • pedrocr 6y ago
      That seems to be for a 2006 Daikin model: > The heat pump model is based on linear interpolation in a performance map retrieved from manufacturer data (Daikin Europe N.V., 2006). And that model is half as good as the modern one I linked: > The nominal coefficient of performance (COP) is 3.17 at 2/35ºC and 2.44 at 2/45ºC test conditions (i.e. air/water temperature) for full load operation. And even then it gets a COP of 2 at -15C. So modern systems getting to at least 4 at -15C seems likely. This claims there are low ambient mini splits that maintain 100% efficiency down to -15C: https://www.ecomfort.com/stories/1341-Keeping-Your-Mini-Split-Working-Through-the-Winter.html https://www.ecomfort.com/stories/1341-Keeping-Your-Mini-Spli... That should cover most places but for really cold climates ground source heat pumps seem ideal. From what I've seen there are simple solutions where a single vertical hole is drilled with common well drilling machines and a single tube that has the loop inside is driven down. Makes it easier to retrofit and implement in small properties.