Grant Aerona ASHP - anybody know anything?

[aa44]

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).

[mad fridgie]

Had a look, it is JUST about possible to acheive the COP, if is practcally possible well that another question.
They do have a correction data, on the web site, this quite well done. You have a % change for ambient and water variables.
If the COP is 4.8 or 5.8, the difference in saving is very small (3% ish).

[desA]

Ask Grant to quote you the mid-range COP for the unit & to guarantee it. If Grant gets COP of 5.8 heating hot water to around 60-65'C, then he'll be awarded the Nobel prize next year, I'd imagine.

An instantaneous COP,hp of 5.8 is possible, of course, but this will depend on source & sink temperatures. COP drops off as sink temperature rises, or source temp drops. Many manufacturers cite COP values at low water delivery temps. Please be aware of the potential Technospin factor.

[yangchenchen]

As to the COP, we should confirm the working condition: evaporating and condensing temperature, the higher the evaporating temperature, the higher COP; the lower the condensing temperature , the higher COP. So only say COP without working range is meaningless.

[desA]

The units look to be fairly well made, I must say. All the very best to them.

Would expect some compressor issues in warmer climates, though.

[fanjoe1]

Grant were at Ecobuild show in London with there new heat pump a few weeks back. I too asked about the COP, and they had testing certificates with them from BISRIA. Clear as day the certificates proved the COPs stated on their site. They did say they had been developing the heat pump for two years and that it just does heating, not cooling, hence the COPs are so high. Nice looking unit though.

[Archie Green]

I am a heating engineer and I have installed one of the Grant HPs in my newbuild property and so far, so good - even in the extremely cold weather this winter we were still getting some sort of return. I am now looking to expand my business from just oil and gas into the HP market.