Context: I am not a fridgy, I work with electronics. I would love to answer my question by tearing open a dozen different aircon units, but I’m sorely lacking in that department.
Question: Are there some optional components or fancier materials that are simply too expensive to use in the lower end aircons; but are used in the higher efficiency expensive units? The range of COP/EER I see advertised is wild, from 2 to 6 or so.
I already vaguely understand that these things help efficiency:
- Bigger indoor & outdoor coils with more metal in them (working fluids get returned hotter/colder gives better carnot efficiency)
- Operating compressor at its optimal power level (I believe they have an efficiency vs power curve with a single peak, so it’s better to use a bigger compressor if you need more power output)
- Inverter control instead of on/off control (most situations, but technically some use cases will have them on par)
- Choice of refrigerant (but that seems to be controlled in my market, I have not seen many options)
Is there anything else they change? Or is that most of the difference?
I don’t think I’ve seen variable speed fans and compressors mentioned. If the thermostat can learn the heat loss/gain it can let the compressor/fan spool down to use less electricity occasionally. Also not all motors are at peak efficiency while they’re at peak speed, so slowing it down can reduce electricity usage more than it reduces heat transfer.
Eta: variable speed can also prevent cycling where the air conditioner runs full blast for 5 minutes an hour because it’s oversized or not hot enough outside.