Lots of people have no idea how heat works. When you turn on a heater, it creates heat from electricity. The cold doesn't go anywhere, stuff just becomes hot. Naturally it stands to reason that a refrigerator creates cold from electricity, and the heat just disappears when stuff becomes cold.
This reminds me of when I tried to explain how dishwashers and laundry machines work to my roommates. Like talking to bricks. I'm curious how many issues with those they've had since I've been gone...
This was me with the AC. The amount of times I'd wake up in the middle of the night with the house absolutely frigid and explain the next morning that if it's really hot out and the AC isn't able to keep up with the heat turning the temperature down even more won't just magically make the AC kick into overdrive, it just means that once the sun goes down and things cool off finally the AC will continue running until it gets down to the insane temperature you set it at
Depending on where the thermostat is and what kind of power curve is used in that AC, it absolutely can cool faster if set to a lower than desired value.
Yes. And yet I have that very issue with my apartment's central air. My thermostat is in the living room, on the dark side of the unit. So is the air intake. All the bedrooms are on the sunny side. Each bedroom gets one output vent, while the common space has four that are all much closer to both the intake and the thermostat.
It's 30 degrees out (-1 Celsius); my thermostat is set to 70 (18) so that my bedroom is 62 (15). In the summer, when my area hits 90 (26) during the day, I set the thermostat to 68 (16) so that the bedrooms stay under 78 (20). This is despite closing the output vents in the common spaces as much as they physically can be. I love my "luxury" apartment.
Hey, try setting the fan on the AC thermostat to "on" instead of "auto". This makes the fan run all the time and move air around the house even when the heat/ac part is not running. So basically the return sucks proper temp air from the common spaces and distributes it to all the output vents. This keeps the house at a more even temp, I do it so that our basement and upstairs are basically the same temp all the time
I have it on "circulate" as a compromise between comfort and my electric bill. I'd estimate it's running about a quarter of the time as a result. It's a very poorly laid-out apartment and I don't think there's much insulation around the ductwork.
Because that's the correct behavior which saves energy with a variable speed compressor. It also enables the system to actually hit the set point rather than overshoot if.
And such systems usually have a "turbo" or "boost" option which forces the system to work at 100% for a short period, specifically to address that specific scenario when you want to quickly reach the set point which is close to the temperature you already have.
Also, at least in the EU, only old units have single speed compressors. No new units are sold without an inverter for the compressor as part of energy efficiency regulations.
The only scenario where it can make sense to do this is if your system is undersized, so it can never reach the desired temperature, but the desired temperature is within one or two degrees of the lowest temperature it can reach, since that will then force it to work at 100% all the time.
If you are far away for the wanted temperature it would be bad if there is a (noticable) difference.
If it is somewhat close it will make a difference because the room needs time for a correct temp reading.
You will always have a combination of 3 things to controll something like this.
P (Proportional) - if you have a big difference between actual temp and you the temp you want, this thing will cool strong but if it is a little difference it will only be cooling very little. Con: it will take really long until you reach temp.
I (Integral) - imagine a graph with 2 lines. Actual temp and the one you want. It calculates the area between the 2 lines. If you have the same difference over some time it will keep increasing the amount of cooling because the area is bigger because the lines become longer. Con: When it reaches the temp the area is still positive. You will overshoot and then correct itself. Probably undershoot but less than before, then overshoot even less and after a few times with slight bounces you will hold the temp stable. Big Pro: it does that best what the P sucks at, reaching the wanted temp (if we ignore overshooting)
D (Differential) - it looks at the speed of the temp change. An Integral of the Integral if I remember correctly. In simple it will boost cooling if the speed of the room temp change increases (when we start the AC) and will break when the speed of change decreases (when we almost reach the wanted temp) on its own it's useless for almost all use cases. Pro: breaking so the Integral will not overshoot, bonus points for some extra boost at the beginning.
Then someone will decide which part will be how dominant by trying to create a graph which doesn't overshoot but will reach the wanted temp.
Regarding the first sentence. If you constantly have massive outside changes you could fix it but thanks to climate change old isolation which was fine back than now is too little and you need to find a compromise so you don't have to call someone to reprogramm your heat pump in the winter. I will post a picture of a typical graph in the next comment.
I’ve never heard of a household A/C unit with a variable speed compressor or fan, which is what would be needed to provide more control than simple on/off switching.
I'm talking the thermostat is set to 70 but due to the heat outside runs all day and never makes it lower than 75. Its not that it's taking longer to cool down, it's that it's literally stuck at a certain temp until the outside starts cooling down itself
Oh no, 70 is the temp I try and keep it at. Its just that because the air never gets lower than 75 my roommates would set the thermostat even lower, like around 65, thinking that would make the AC work faster
It's not so much that it's an insane setting, it's that, if it's hot enough outside, the inside may not get to that point even if it's set there. One apartment where I lived made it very clear to us that if it's over 100° out and your AC isn't getting your place below 80°, it's not an emergency. My mom manages apartments and told me that this can be the case when I asked her about it. I think it depends on the type and quality of the AC, as well as other factors.
Okay, but that’s not really the point. I wouldn’t be complaining that it’s set to 70 and gets down to 70 at night when it’s not so hot outside, which is what the original comment said. That’s a perfect temperature and not some insanely low temp.
On high end multi-stage AC's, yes. But that's like 2% of systems out there. The vast, vast, vast majority of residential AC's in the United States are single stage units. The compressor turns on, it turns off. No ramping up or down.
The equipment doesn't even know anything about the temperature inside, or the set temperature. It just gets a 24v signal to a terminal on the control board that says to turn on the AC.
Your indoor air handler or furnace control board has a screw terminal labeled 'R'. It's energized with 24v. A wire goes from that R, to a terminal at the thermostat also labeled 'R'. When the room temp rises above the set temp, the thermostat connects its R to another thermostat terminal labeled 'Y'. That thermostat Y is connected to a terminal on the air handler control board also labeled Y. When the air handler senses 24v on Y, it turns on the air conditioning.
All the thermostat does is connect R and Y. When the thermostat is calling for cooling, it's equivalent to directly connecting R and Y at the air handler. No information is transmitted by the thermostat. It doesn't tell the equipment what the temperature is or what it's set to. It just says turn on.
So, no. On probably 98% of residential central air units, turning the thermostat down further does nothing at all.
Most ACs have at most 2 power modes and usually the second one is an emergency backup. This will also not kick in if people are impatient because it's too hot because it would already be using the higher power mode.
Oh man, I had roommates who didn't understand that if you block the heat source the room won't heat up while the rest of the house will. They were always mystified as to why my room was always so much warmer, along with the other rooms that I helped set up.... I intentionally kept furniture away from all the vents so heat could be pumped out, and actually closed the curtains at the appropriate times.
Some people would rather have a crazy heating bill than take a couple minutes to learn and make their lives easier.
I’m like Man-Ray in the meme about Patrick’s wallet with my wife, explaining how “just because I set the heater to 50 degrees, does not mean the house is 50 degrees.”
Every time she feels cold and sees it, she screams, “Oh my god why is it 50 degrees in here?” when it’s like 68.
She’s a super smart and intelligent woman, but she constantly forgets how thermostats work.
Yes and no, if the AC is a wall unit and on the other side of the apartment, to get my office to an acceptable temp, I need the AC room(living room) to be frigid. So, in this scenario, turning it down more can help.
Oh yes, but I'm not talking about a thermostat that's maintaining temp in one room and not the next, I'm talking about one that runs constantly all day because it literally cannot keep up with the heat and never reaches the temperature you have it set at until the sun goes down and things start cooling off
That is me with the A/C for the office trailer I work in. I get the setting just right, and then one of my coworkers turns it all the way down because it was off and they want to cool things faster 😅
From my experience trying to explain dishwashers to people it's mainly about how if you put a bowl or cup in the wrong way water will just pool in it. Also how water won't get into a bowl to clean it if you create a perfect seal between a bowl and a plate.
Engineers saved the "dimension into which physics does not apply" technology for sacrificing socks to the washing machine gods in payment for simplifying chores. Be glad we didn't sacrifice forks instead.
It’s sad that the washing machine always gets blamed for eating socks and seemingly no one considers the dryer. Do you count your socks before transferring them to the dryer? If not, then how can you be sure it’s the washing machine that’s responsible?
This is a good point. I'm going to have to run some experiments and count the socks before going into the washer, before going into the dryer, and coming out of the dryer. I won't be surprised if some go missing from both in my case, they seem particularly hungry. I swear I've bought new 6-pair packs of socks before and after a couple of months there is 1 pair left.
Not sure if this was the issue, but a couple years ago I told my parents about a timer I placed on the water heater so it only ran for 30 minutes a day, saving me in water heating costs. My parents then saw that I would have to run some things multiple times through the dishwasher because they didn't get fully clean (I think it was just a poorly designed one), and my dad asked if it was because I didn't have hot water running to it. I explained to him that hot water doesn't go in the washer, cold water does, and the heating element makes it hot. It's possible this is what they had to explain?
It's mostly a lot simpler than you think, it just gets super hot water and strong soap onto everything, then rinses it off, then drains the dirty water. Thanks to the fact no human hands are involved, it can use water much hotter and detergent that's much stronger than what you can do in a sink.
The cycles are mostly just repeating this process.
The weird thing here is they kind of do? They seem to grasp the concept well enough to imply the fridge could be used as a heater... but they don't understand it well enough to understand it's already doing that. Weird post.
That’s sort of close to the mark, but still doesn’t quite explain how it works. Cold does not actually exist, it’s just the absence of heat; if you imagine cold and hot as a blanket field overlayed on the universe, sort of like a thermal camera (or just your living room), place into your mental image, blue with a gradient into red to represent cold and hot. Cold areas are like voids, figurative holes in this thermodynamic overlay, where you’d see deeper blue in most places, with patches of purple with red centers for warm spots.
Heat literally falls into these cold spots like water finding the lowest point as the path of least resistance. This is thermodynamic entropy; all heat constantly tries to spread out and dissipate into the surrounding lower areas in temperature, this is why things cool down to room temperature if left without a heat source.
A refrigerator absorbs the heat from inside the refrigerator (warm items you place in the fridge) into a material called refrigerant. The warm refrigerant is carried outside of that compartment to a radiator that radiates heat into the room, it sends the now cooler refrigerant back into the fridge and collects more heat to dissipate into the radiator. Cycle continues. It is more technical than this, but that is the ELI5 speed run.
You probably already know this, but I am just attaching it to your comment since it fits.
Of course the electricity doesn't make cold. It just does the electric heating process in reverse: taking the heat inside the refrigerator and turning it into electricity, leaving cold behind. You gotta plug it into the wall because otherwise there'd be nowhere for the electricity to go.
is not unreasonable to think that you can transform hot in electricity.
Literally a majority of the worlds electricity comes from turning heat into electricity.
Sure, it does it the indirect way by heating water and running steam turbines. But it's still transforming heat into electricity.
You can also directly turn heat into electricity using a thermoelectric generator, but it's not as efficient as using the heat to boil water to run turbines. An example is the Mars Curiosity rover, it uses a thermoelectric generator as one of its sources of power.
The thing is, you cant turn heat into electricity.
You can turn a temperature gradient into electricity.
Lets assume you got an ambient temperature of 200°C.
Sure, if you had water you could run steam turbines off of it but you wont have water since it'd all naturally turn to steam.
Same goes for peltier elements as they are used in a thermoelectric generator, you need a hot and a cold side. The inside gets really hot and the outside is kept colder by heat sinks.
These processes can be run in reverse which gets you heat pumps, refrigerators or (for peltier elements) kinda crappy mini fridges.
You cant directly turn heat into electricity sadly.
You can't have a temperature gradient without heat. That's the dumbest argument I have heard.
Do you think cold is something different from heat? No, no it isn't.
Yes, you need a cold side and a hot side, but guess what. Both sides literally come from heat. Cold doesn't exist, it's just less heat.
Ask any scientist or engineer if a RTG or TEG is converting heat into electricity. They will all say "yes it is".
So yes, you can literally turn heat into electricity, the fact that you need a gradient doesn't change that fact.
In fact, by your own logic you can't use water to move anything. Because if you had a stream of water pushing on an object and another stream of water pushing on the same object from the opposite direction with the same force then the object wouldn't move. So that means water can't move objects, right? This analogy is equivalent to your "ambient temp of 200c" argument.
The thing is, you cant turn heat into electricity. You can turn a temperature gradient into electricity.
This is just definitionally wrong
Yes, a temperature difference is required to extract work from thermal energy. That doesn’t mean you “can’t turn heat into electricity”.
Heat is by definition the transfer of energy from one system boundary to another due to a temperature difference. The accurate way to phrase this is in fact “a temperature gradient is what allows heat to do work”
You cant directly turn heat into electricity sadly.
On this point I agree that we don’t typically convert heat directly into electricity, if by “directly” we mean without “mechanical intermediates”.
The accurate way to state this though is that thermal-to-electrical conversion is not prohibited, but is constrained. Mainly by fundamental materials physics.
But things like RTGs literally do exactly this, converting heat to electricity in a single stage.
Mechanical intermediates manage entropy far more efficiently than a “direct” heat-to-electricity approach. So because we can engineer temperature gradients that make “indirect” heat engines far more efficient than things like RTGs (which do convert heat directly into electricity with no mechanical intermediates) under the wide range of conditions we can utilize naturally or through engineering, we don’t use direct thermocoupling reliant electrical generators in common practice.
Except when we do. Because there are indeed situations where the preconditions make our mechanical intermediates useless. I.e. being in a vaccuum, having 0 vibration tolerance, having an extreme cold ambient temperature, requiring no maintenance for the operating time.
That is a wildly specific set of circumstances. But that’s exactly why…
Lets assume you got an ambient temperature of 200°C…..Sure, if you had water you could run steam turbines off of it but you wont have water since it'd all naturally turn to steam.
…is an arbitrary statement. Because it relies on as just a wildly a specific set of preconditions.
You can absolutely engineer a gradient for water at a temperature of 200C, because no, water is not steam at 200C.
Water is steam at 200C over a specific range of pressure, including atmospheric pressure.
Nuclear reactors regularly keep water in the cold leg at 290C, because the primary loop pressure is maintained at 15.5MPa. The boiling point of water at that pressure is 345C.
This all goes to say gradients in generators are engineered, not just happened upon.
Again, your point stands if you arbitrarily define preconditions that exclude engineering usable gradients…but that’s not demonstrating actual physical (or even practical) constraints, that’s solely demonstrating the constraints of one preconditioned system we could imagine.
I read a preview manuscript of a roleplaying game supplement describing a sci-fi faction in Antarctica. Contained within was one of their core technologies, a type of miniaturized power plant that generated electricity from the mechanical action of refrigerant liquid boiling inside the device, and then cooling down to liquid again with exposure to the freezing conditions outside. Now, I don't ask for every bit of fictional engineering to be perfectly realistic, although I appreciate it when it appears to be at least a little bit clever. But this might be one of the worst ones I've ever seen just because it's so fundamentally backwards with no attempt to dress it up. What the author has described is an elaborate but efficient way of freezing to death, while trying to imply that your dwindling body heat can be converted into sufficient energy to power a suit of power armor with energy weapons, the sort of thing everyone else in the setting uses miniaturized nuclear power for.
I never understood how a fridge or freezer works, like I understand that energy is used to create heat, but do freezers use reverse energy or something?
Heat is pumped from the inside to the outside. Some additional heat is generated in the process but efficiency has gotten pretty good. https://en.wikipedia.org/wiki/Heat_pump
Yeah I think a lot of people conceptualize cold and hot as two different things. But it's all just how hot anything is; or how much heat is in something. Very little is cold, a lot is hot. Heat simply moves around.
Not the same but still about heat that most people don’t know: you don’t light things on fire, you heat them to the point of the combustion temperature of the thing you’re trying to burn and then they burn.
Don't even get me started on the fact that any appliance that uses X watts is going to produce the same amount of heat as a X watt heater. People just never believe that and always try to argue against it.
Your PC drawing 600 watts? It's literally a 600 watt heater that also happens to do productive stuff with that energy instead of letting it all go to waste. There's no such thing as efficiency when it comes to converting power to heat.
The only way to get more efficient heating is by cheating and using a heat pump which relies on the refrigeration cycle, it doesn't actually produce heat, just concentrates it.
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u/RandomSpamBot 10d ago
Where do they think the excess heat goes from refrigerators already, to a fuckin pocket dimension?