Warning: None of the participants in the Great Air Conditioner Debate Of 2022 have endorsed my summaries of their positions in this post. Including me.

Background

In Everything I Need To Know About Takeoff Speeds I Learned From Air Conditioner Ratings On Amazon, I complained about the top-rated new air conditioner on Amazon. I claimed that it’s a straightforward example of a product with a major problem, but a major problem which most people will not notice, and which therefore never gets fixed. Specifically: although it does cool the room, the air conditioner also pulls hot air from outside into the house. People do notice the cool air blowing from the air conditioner, but don’t think to blame the air conditioner for hot air drawn into the house elsewhere. Simply adding a second hose would fix the problem at relatively low extra cost, and dramatically improve the effectiveness of the air conditioner. But companies don’t actually do that because (apparently) people mostly don’t notice the problem.

To my surprise, multiple commenters disagreed with my interpretation of the air conditioner example. They argue that in fact one-hose air conditioners work fine. Sure, single-hose air conditioners are less-than-ideally efficient compared to two-hose, but it’s not a very big difference in practice. CEER efficiency ratings account for the problems, and the efficiency difference is typically only about 20-30%. Also, The Wirecutter tested lots of portable air conditioners and found that there wasn’t much difference between one-hose and two-hose designs. (Credit to Paul for both those pieces of evidence.) Really, what this example illustrates is that simple models and clever arguments are not actually very reliable at predicting how things work in practice. One should instead put more trust in experiment and reported experiences, including all those 5-star ratings on Amazon.

I, on the other hand, think the “second hose doesn’t help much” claim is a load of baloney. I think it is far more probable that CEER ratings are bullshit and The Wirecutter messed up their test, than that a second hose makes only a small difference.

And so began The Great Air Conditioner Debate Of 2022.

… Why Do Air Conditioners Need Hoses?

Ideally, an air conditioner should work much like a fridge: it pumps heat from air inside to air outside. Inside and outside air do not touch ...

Air Conditioning