Eli5, Why the lowest (coldest) an Air Conditioner is able to set to, is 16 celcius?

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As the title says, why is that the case? (16 Celsius ~ 60 Fahrenheit)

I’ve read somewhere, that 16c is suppose to be the most efficient / comfortable?

Prob need an AC techie here, but I’ve experienced being in my car during summer & have to hit the “max” button on those really hot days, & it automatically goes straight to high fan setting + 16 celcius.

How come it doesn’t go futher? Like 12 or 10 Celsius?

& I’ve also experienced my home AC, where I’ve set it to 23 celcius, but a larger horsepower (4 or 5hp) & it’s freezing!

Thanks, for the insight 😊

In: Engineering

6 Answers

Anonymous 0 Comments

Lower than 16°C air can have negative health impacts and is quite uncomfortable for almost everyone.

The temperature you set it at has almost no bearing on the rate at which its able to work, as an aircon has a BTU/hr rate which is how much heat it can reject per hour.

Anonymous 0 Comments

There is no technical reason, it is just a user experience decision that the manufacturer has decided. Their thought process is that nobody would want to run the AC when the temperature is that low compared to the average room temp. So what you must want is just the maximum AC power possible.

Anonymous 0 Comments

The reasons already given are valid. That said, it’s set by the manufacturer, possibly for these very reasons, but there’s no physical reason they can’t have a lower or higher minimum setpoint. As explained by others, people don’t really set it that low anyway, most people wouldn’t be affected if that minimum setpoint was raised to 65F or a bit over 18C. Conversely, the thermostat in the house I grew up in had a minimum setpoint of 58F, which is 14.4C, and it was incapable of reaching that setpoint because this house had a swamp cooler (evaporative cooler- water flows over absorbent pads and the blower fan for the system draws outside air in through these pads, the air temperature drops as a result of the water evaporating but not below 60 degrees Fahrenheit in most situations).

One thing to keep in mind is that an air conditioner moves heat from one location to another. Inside the space being cooled to outside the space being cooled. There is a point at which heat is coming into the space from outside through cracks, crevices, space between doors and walls, through the actual walls themselves as they get heated by the sun, etc is coming in faster than the system can remove it. An example would be a house like mine with an undersized unit. Even with all new doors and windows and a fairly new system, the mass of air in the house plus all the objects that will heat the air back up as air temp drops and the heat coming in from things like sunlight warming the house is high enough that the unit can’t really deal with a difference of more than about 26 degrees Fahrenheit between inside and outside. Most of the year that’s fine, but when the temperature gets above 100F and the humidity is above 65%, 74 degrees feels a little uncomfortable. The system can maintain that and even cycles off for a while, so it isn’t having trouble, but if I set it to say 71F, it runs and runs until the safety makes it shut off (continuously running for extended periods does bad things to some of those moving parts) and the temperature never drops below about 73. When it gets REALLY hot out (105 or higher) that minimum level the system can achieve goes up fast as the system can only push so much heat out into the already hot outside air.

Anonymous 0 Comments

Mostly because this is considered the optimal balance between cooling efficiency and preventing the unit from freezing.

By taking away heat from the air, an air conditioner lowers its temperature—cooling air below a certain temperature can cause the air conditioner to freeze up, which can damage the unit and make it less efficient. At temperatures below this threshold, the risk of freezing increases, especially if the air conditioner is operated for extended periods.

Anonymous 0 Comments

You can go lower if you bypass the controls with a coolbot.

Source: we built a walk in cooler on my farm using a 14000btu window ac and a coolbot controller.

Anonymous 0 Comments

Little tip: when you get in your car on a hot day, don’t set your AC to max and let it blast. Yes it will cool down your car and it will blow hot and then cooler air while it does so but it also works overtime. Set your AC to 2-3 degrees Celsius (I don’t know how to convert that to Fahrenheit) lower than the outside temperature.

It’s not as taxing on your AC and achieves the same result.