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Air conditioner efficiency: what do they change other than using more materials? (aussie.zone)

submitted 6 days ago* (last edited 6 days ago) by [email protected] to c/askscience

13 comments fedilink hide all child comments

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?

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[–] [email protected] 7 points 6 days ago (1 children)

For portable air conditioners, many inexpensive units have only a single hose (hot air exhaust) rather than a dual hose (outside air intake and hot air exhaust) which is going to cause inefficiency (like, you're going to be pulling air from outside into the house by creating a pressure difference).

[–] [email protected] 6 points 6 days ago* (last edited 6 days ago)

Definitely. Absolute scams. They deserve the "0 energy stars" ratings I've seen printed on their boxes.

My family bought one of those for one of my grandparents. On a 35degC day it was only able to cool the room by a few degrees and it was still humid inside.

Converting them into dual-hose systems would be so simple (almost free) to the manufacturer, but instead they rely on deceiving buyers with a promise of something that is not delivered.