Opening the app for the first time on my Fairphone 5 (listed as unsupported) actually crashed the OS, but after that it seems to be working ok.

Closing out of the in-app gallery causes the app to crash. But that can easily be worked around by using some other gallery app.

I’ll be testing it for a bit to see how it fares against other HDR methods…

Not an expert but these systems are fairly self-contained and robust. A few things that can be checked easily is that the fan spins, the radiator is free of debris and some compressors might have a sight glass for the oil level.

Any other checks regarding performance of the system, leaks and refrigerant level require you to perform a full refrigerant discharge and recharge. That takes special equipment and some time so no one in their right mind would do that for free, unless they can then force/guide you into some kind of upsell situation.

Larger systems might have some kind of oil filter/catch-can that you might be able to check easily but I’m not too sure on that.

After all heat pumps are just plain old A/C units with a reversible cycle.

Out of curiosity I’ve let it rate Low<-Tech Magazine, a website run on an ARM SBC powered exclusively with off-grid solar power, and that only achieves 87% / A.

Link to results

Cool to see support for the QOI format in a popular software package.