On another forum that I use, somebody asked a question today about Grant Aerona heat pumps. I have never heard of them but, looking at their web site they claim a COP of 5.8 (at A7/W35) for the biggest model (15.5 kW). I am in the market for an ASHP and all the other models that I have looked at struggle to get much above 4 so I am a bit sceptical of their claims.

Looking at the site, it appears as if these are the first heat pumps that Grant have produced. I can't understand how they could produce such a leap in the COP. Also, the COP seems to rise dramatically with the size of the machine. The smaller models have "standard" COPs of 3.9 to 4.3 but then the 12.5 kW machine claims a COP of 4.8 and the 15.5 kW a COP of 5.8. It sounds too good to be true. They don't publish any data for COPs at other temperature combinations.

Does anybody know anything about them?

(I know this sounds like spam but I have absolutely nothing to do with Grant. I am about to build a house up here in Shetland and have a meeting with a Mitsubishi Ecodan installer this weekend. I was just really surprised at the claimed COPs for these machines).