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?
Micro channel vs tube and fin coils is another area for you to look into in terms of build differences.
Then you get your indoor coil shapes, A coil vs N coil. You got your pistons vs thermo static valve (txv)
there is a lot of areas in the equipment and accompanying equipment that will throw those efficiencies out the window…
Microchannel coils: Wow. I assumed the pressures were too high for such construction to succeed. Thankyou :)
Fluid metering: I was aware of TXVs and capillary tubes, but not reverse bypass piston inserts. Would these options only be a few dollars difference in BOM price between each other? I guess the extra labour from soldering more pipes and connections for a TXV might be more costly than the extra materials themselves.
A vs N folded coils: interesting. I have mostly seen split systems and their unfolded coils, not central AC units with these A & N folded coils.
Cars have micro channel evap coils, central does as well. Not sure about ductless however, probably not unless it’s outdoor
Reversing valve is typically in heat pump applications, allows the refrigerant to flow in reverse effectively supplying heat to the space instead of extracting it.
I’m used to central AC mostly, but I have worked with and used ductless, I’m not overly a fan myself. Controls are too much. I like simple relays and switches, less logic on the board. I want to be able to repair failures easily should they arise.
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.
You should check out the Youtube channel “technology connections”. They have videos that go into detail about heat-pumps. Specifically what the efficiency ratings mean, and how different units compare.
Oh, he’s done episodes on heat pumps? I’m gonna check that out. I weirdly loved an episode about can openers. The guy has a weirdly all access tv way of explaining things really well.
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).
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.
In addition to advances in fin design and compressor and motor efficiency and materials, there’s also the option to use things like heat pumps instead of traditional compressor based ac systems. They tend to be more efficient or for the same size to produce more cold air for the same electricity.
Due to the fact that a heat pump moves heat and it is not a unidirectional process like a traditional compressor system is, heat pump air conditioning systems can be both heaters and coolers at about the same electrical efficiency.
heat pumps instead of traditional compressor based ac systems
Heat pumps are compressor based systems. They are the same technology.
In addition to advances in fin design and compressor and motor efficiency and materials
This reads lot like an answer from an LLM. Did you use one? My apologies if not, but you sound very suspicious.
No I didn’t use an llm and yes a heat pump does use a condenser or a compressor but it’s not the same as a Freon based compressor system.
Yes, heat pumps use probably a Freon based refrigerant but they operate in a slightly different manner.
How is being a heatpump (a reversible air conditioner) automatically more efficient?
If you have 2 units using identical design, but only add a reversing valve, I don’t see how the heat pump version would be any more efficient at cooling.
