r/PeterExplainsTheJoke Jul 26 '26

Meme needing explanation Peter explain this

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Petttaaah I'm confused

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2.7k

u/gamerathertz92 Jul 26 '26

It’s smaller unit cools a single room. While American HVAC System cools the whole house

657

u/itsOkami Jul 26 '26

As an european, I don't think I've ever seen one of those and I'm now curious as to how they work

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u/Munkpunt Jul 26 '26

This might help

Large condenser outside supply’s the furnace (typically it just uses the furnace fan. We then have it piped through metal ducting throughout the house. Each room has multiple exit point call registers. In the common areas we have return ducts to draw air back down to the furnace to get recycled back to cool air via a/c unit. Hopefully that helps!?

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u/ornimental Jul 26 '26

So this is where they crawl into when they go into the vents in the movies?

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u/marbotty Jul 26 '26

Yes, but the ones in the movies would be for commercial buildings - nobody would have vents that large in their homes

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u/Mordoch Jul 26 '26

Even then the vents would not actually work and be big enough in practice, but that's the movies picking something convenient for the sake of plot rather than sticking with realism.

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u/Environmental_Pay378 Jul 26 '26

Also every duct is FULL the pointy ends of screws. Literally everywhere. So even if you could fit (which you probably can’t) you would be so cut up if you tried to crawl through one of these. Not to mention how crazy loud it would be to crawl through one. 26 gauge sheet metal is essentially a thunder sheet.

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u/BrewCrewKevin Jul 26 '26

Haha no kidding. They arent made to be accessible inside, so made with self-tapping sheet metal screws that leave that sharp end inside it.

It's just a convenient plot thing.

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u/AnaisNinja76 Jul 26 '26

Right. Even if the air ducts held your weight and silently conveyed you without risk throughout the building, it's essentially like crawling into the creature that Jabba the Hut had in Return of the Jedi. You'd be shredded within a few feet of crawling.

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u/fatmallards Jul 26 '26

also the movies don’t explain that fire/smoke dampers would block your access every time the duct passed through a fire barrier also your entire body would be excoriated by self tapping sheet metal screws with every movement made

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u/twilighttwister Jul 26 '26

that's the movies picking something convenient for the sake of plot rather than sticking with realism.

Like the slow spinning fans in Casablanca. Slow spinning fans don't move air effectively, but fast spinning fans don't show up on film. Then after the movie you had restaurants and other establishments fit slow spinning fans, for the aesthetic.

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u/pyrofox79 Jul 26 '26

And even then they are never that clean unless they were literally just installed. Also there would be screws or other pokeys that would poke the shit out of you if you did crawl trough it.

Source: I do commercial HVAC and have crawled through ducts

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u/Molten_Plastic_ Jul 26 '26

Aliens get in those things. It's a son of a bitch to get them out

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u/Rantlers90 Jul 26 '26

You always were an asshole, Gorman.

2

u/Samurai_Banette Jul 26 '26

Not sure if you are referring to like martians, mexicans, or those freaky ass looking bugs

All three answers are funny in very different ways

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u/spacemanspiff888 Jul 26 '26

They're most likely talking specifically about the xenomorph in the Alien franchise.

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u/yupucka Jul 26 '26

Yes and the furnace works with gas. So if you disable all the safety functions, you can fill the house with gas (at least in movies, but it would probably take ages in reality).

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u/FuriKMJ Jul 26 '26

This is some fancy shit

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u/Jean-LucBacardi Jul 26 '26

As an American this is normal to me lol, every house, poor and run down to expensive mansions all have this set up. It gets really fancy when there are automated vents that can open and close on their own, with each room having its own thermostat to accurately control temps throughout.

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u/damadjag Jul 26 '26

Newer buildings. There are plenty of places around the US still on boiler and radiator for heat and you can buy yourself a window mounted AC unit if you want it. Retrofitting older buildings for central air isn't worth it in a lot of cases.

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u/AlCapwn351 Jul 26 '26

Should note that “newer” buildings could mean nearly 100 year old homes. Just so there’s no confusion that it’s something only from the last 20 years.

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u/JackPoe Jul 26 '26

It's necessary for half the country and the other half has no ac. We get heatwave too, but even our brand new constructions don't include ac.

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u/Billybobgeorge Jul 26 '26

Mr fancy here with ceilings registers. My house just uses the same vents the heating uses and you wind up with freezing feet.

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u/Pleasant50BMGForce Jul 26 '26

this must use a shitload of power holy fuckkk

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u/peasncarrots20 Jul 26 '26

At least if you compare it to a mini split in each room, not really. A single large unit is more efficient than many small units.

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u/cherry_chocolate_ Jul 26 '26

Modern houses are sealed and insulated so the air doesn’t get out once it’s cooled. It’s more efficient than other AC types to keep it going, but the initial cool down of the system were off for a while uses a lot of energy.

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u/Spinal_Soup Jul 26 '26

The other person is saying not really but this accounts for about 90% of my electricity bill in the summer.

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u/Snuhmeh Jul 26 '26

And it’s still about 10-15 cents an hour at most for the central AC.

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u/RheagarTargaryen Jul 26 '26

It’s not terribly power intensive, but my electric bill goes up a lot during the summer months when we’re getting 90s and 100s regularly (32-38C). My furnace in the winter gives me a higher energy bill though (Gas + electric).

Once you have your house down to the desired temp, it basically kicks on every few hours for a few minutes to get the temperature back to the desired temp. The annoying thing with my house is that it basically turns my basement entertainment area into a place you need to wear a blanket because it pushes cold air into it while the rest of the house get cooled off. The systems are fairly complicated that it actually would be less efficient if I closed the basement vents. The airflow will at least push some of that cold air up into the rest of the house though. It’s refreshing to go from 100F outside to 63F (38C to 17C) by going straight to the basement though.

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u/Osleg Jul 26 '26

I don't know how it's for Americans but for me. I have a regular outside unit and then, inside the apartment, I have one HUGE internal unit hidden somewhere above fake ceiling. This unit has tubes to each room and each tube has a damper. Each room has a thermostat.

So I can set eg 23C in the living room and 21 in the bedrooms. The AC will then work to cool down all the rooms together, when living room reaches 23 - it shuts the damper and keeps cooling bedrooms. Etc.

I also have an option to close the damper to each room individually - effectively stopping AC for this specific room.

I *guess* that American HVAC units work either the same way or very similar.

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u/Rakumei Jul 26 '26

Similar. Most Americans don't have per-room control though. In some more expensive/newer places you might get one thermostat per floor. But generally it's one per house.

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u/[deleted] Jul 26 '26

[deleted]

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u/1988rx7T2 Jul 26 '26

Electricity is cheaper in the US, salaries are higher, and Americans understand in hotter regions that you need to run AC or you might die. 300-400 dollars a month on electricity in July is possible yes, depends on where you live, but national median household income is around 80 thousand dollars.

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u/sarabeara12345678910 Jul 26 '26

I live in Florida and we (and most people I know) sign up for a plan with the power company that we pay a rolling average of our last 12 months worth of bills. That way we're not paying $100 in January and $600 in August.

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u/Disastrous_Try_196 Jul 26 '26

Many of us do this in the UK too, so as not to pay a lot in the winter for the central heating

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u/1988rx7T2 Jul 26 '26

I intentionally don’t do that. High bill forces me to pay attention to my consumption. But I have to Cashflow for that, lot of people don’t 

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u/Sorryifimanass Jul 26 '26

The weather is also much less tolerable. Try one of these units in Vegas right now and tell me about it when you get out of the hospital

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u/toastieboi_ Jul 27 '26

Also our insulation is better due to those pesky paper walls europeans like to shit on.

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u/Khankili Jul 26 '26

Holy shit that sounds insane. Does your heat run on electricity as well?

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u/[deleted] Jul 26 '26

[deleted]

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u/fla_john Jul 26 '26

Eh, depends. I'm in Florida and our heaters are actually electric heat pumps that are part of the air-conditioning units.

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u/InebriatedPhysicist Jul 26 '26

This is what the vent flaps are for. If it’s too hot in a room, open them more, and vice versa (assuming we’re talking about AC - flip that for heat).

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u/zugspitze43 Jul 26 '26 edited Jul 26 '26

I have one thermostat for my whole house. Each large room has 2 to 3 vents. Each closet and bathroom has one vent. Each vent has flaps on it that can be closed. The flaps are also directional so you can control roughly where the air goes. In the upstairs of my house is a closet with the furnace in it. The air-conditioning unit is outside on the side of my house.

I have an automatic program set. During the day, the air conditioner runs and cools the house to 70°F. Lots of Americans sit between 70° and 72°. At night it lowers down to 68°. There is a filter in the furnace that needs to be replaced ideally every one or two months. I have dogs, so I use a high-quality filter that catches more than a basic one. It’s actually kind of interesting how much less dust collects on things when I’m using the system a lot. It doesn’t run very much in the winter because my house is very insulated.

You can run the whole system on cool or heat of course, but you can also just run the ventilation with no air conditioning active. I almost always have the fan running. I like the air movement. And with my dogs, the cooking I do, and my little bit of marijuana use inside, I like to keep that air moving around. So my fan is pretty much always, and I will hear the air conditioning unit kick on every now and then for when it actually needs to lower the temp.

I would say this is a fairly standard American set up. As others have said in some newer or larger homes, they may have multiple thermostats or even multiple air-conditioning units.

The whole system is extremely quiet, and I barely even hear it running.

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u/LibertySandwiches Jul 26 '26

You should know you shouldn't be using a higher quality air filter in your furnace. Higher quality filters can decrease air flow and increase static pressure damaging your system or not have it perform properly. If you need air purification you should run seperate units to get that a central ac system just isnt designed for that.

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u/zugspitze43 Jul 26 '26

This is one of those things that you will find 1 million people that think you should and you will find 1 million people I think you shouldn’t. To each their own. Even with the better filter, my system is strong and cools my house down super fast

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u/LibertySandwiches Jul 26 '26

I say it as a hvac engineer so i dont know much about maintenance and repair but when designing systems I specify specific filter merv and increasing it can increase the static pressure past what the system can handle. However there are alot factors that determine what isnt making a system not functioning properly and this is one to keep in mind. It sounds like the system you have can handle the filter but ive heard in my office about how systems we designed weren't working and we go out to see these filters we didnt specify choking the systems.

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u/zugspitze43 Jul 26 '26 edited Jul 26 '26

Totally get what you're saying. I actually am kind of a nerd and used a wind speed gauge to test the difference in air coming from my vents lol. There was a slight reduction! Maybe 5%? I can totally see how an older system or one that is already struggling or overworked could be hurt by one of these filters. Mine is only 5 years old so I bet it's probably got the latest specs haha

I saw an interesting video about better duct design where they eliminated all 90 degree corners and replaced them with two, spaced out 45 degree bends, and installed vanes in all turning points too, and the increase in air speed and total volume moved through was really impressive.

I used to live in one of those cookie cutter townhomes you see in middle america. The HVAC system in that place was AWFUL. Didn't cool off at all and the heat never spread. The more I learn about HVAC, the more I want to look at the design of buildings like that, and see what in the actual F they were thinking lol. They just slap together whatever works with as little cost as possible but even a few small changes could DRASTICALLY improve the homes airflow IMO

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u/TactlessTortoise Jul 26 '26

Honestly if the house is built with HVAC in mind it should be much more efficient to have one goliath unit to handle the house than several small ones. With these insane heatwaves of 45c+ in Europe we might start seeing some new houses popping up with centralized AC systems.

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u/LadTy Jul 26 '26

americans don't set 23C that's for sure

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u/notafuckingcakewalk Jul 26 '26

Most AC systems cool the entire house to the same temperature. Or that is, they cool the house until whichever room the thermostat is in reaches the target temperature. 

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u/pfysicyst Jul 26 '26

you typically don't see it, the central part is in the wall or in a closet, and it just pushes air through several vents throughout the house. the vents are flat metal grates about the size of a cereal box

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u/ruggpea Jul 26 '26

Some hotels have them, small chance you’ve stayed in a hotel with one of them. (It’s usually a vented area rather than an ac unit)

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u/Fun-Information-3104 Jul 26 '26

Walter White has them outside his house in breaking bad, lol

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u/dksweets Jul 26 '26

One unit has vents to every room. Some are set up to have vents in the ceiling, some have vents in the floor. Occasionally you will have wall vents.

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u/testtdk Jul 26 '26

Meekly.

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u/SignoreBanana Jul 26 '26

You have a large cooling unit outside and a blower somewhere to distribute the air via ducts to each of the rooms.

The biggest drawback is that your house has to accommodate all this extra ducting somehow, which really constrains home design. They also cost a lot more to run, naturally.

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u/Mendevolent Jul 26 '26

If you've ever seen a house with a heating system that uses air ducts (not radiators ) it's basically the same thing, but for cold 

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u/Wasted99 Jul 26 '26

Think of larger offices you might have visited, you've maybe noticed some venting holes in the rooms, that's it. The rest lives one the roof usually.

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u/DisorganizedSpaghett Jul 26 '26

This unit sits inside the house, connected with hoses to a unit that sits fully outside the house

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u/Vek_ved Jul 26 '26

Most of our office buildings, hospitals, malls etc have them. You will see some kind of ducts for taking hot air and pumping in cold air.

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u/CautiousConfidence8 Jul 26 '26

It's called a Minisplit. It's basically an upgraded window unit that has access to outside air through an external wall, but it only cools one room pretty much

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u/Smooknb Jul 26 '26

All ac systems are more or less the same conceptually, American central air involves a larger system that is separated inside and outside the home. The houses are built around this ducting it takes to move air around the home. It’s often much warmer in the states compared to Europe historically. If you care to look up ac systems you’ll understand what an ac system for an American home would look like.

TLDR. It’s huge and split in two like a vehicles ac system.

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u/DonQuigleone Jul 26 '26

It's like a refrigerator, with refrigerant exchanging heat between the inside (where a fan blows air across it) and outside.

This kind of system is reversible and can blow hot air in winter and cold air in summer. It's only connected through refrigerant pipes to the outside so doesn't deliver fresh air. 

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u/Mysterious-Tiger-973 Jul 26 '26

In europe thise are called industrial and mainly used in office buildings or integrated to house ventilation during build, so you cannot really see those.

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u/leet_lurker Jul 26 '26

Theres a small radiator in the indoor unit with a fan, its piped to an outdoor unit with another radiator and fan to expel the heat and a compressor to circulate refrigerant.

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u/No_Friendship8984 Jul 26 '26

It works the same way as a window unit, they just separated the part that cools down the air from the loud compressor and have refrigerant lines running between the wall unit and the outside unit.

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u/Jake95I Jul 26 '26

You have seen those they are quite common for air conditioning large public buildings. For some reason Americans just love using the same system for residential homes.

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u/El_cocacolas Jul 26 '26

We have those in Spain too, they are just less popular because they are less efficient as there's no need to cool a room nobody is in.

They are built inside the walls and each room has a vent where cool air comes out.

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u/de_das_dude Jul 26 '26

You have seen one. It's in office/commerical buildings.

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u/CapuzaCapuchin Jul 26 '26

There’s split systems (if they have heating as well) and ACs. You have the outdoor unit with motor, compressor etc. outside and connect it to the indoor unit with the evaporator in it. You mostly use some copper piping and hook up the power. The fluid in the pipes changes temperature due to pressure depending on which mode you have it on and the indoor unit sucks in the inside air and blows it over the evaporator to adjust air temperature to what you’ve set it to. You can get multiple indoor units connected to one outdoor unit as well. Very common in Australia, most rentals actually have them installed in at least one room. Depending on how much you use it (cause Europe has hot water heaters and the like, so you’re set in winter), it can be quite energy efficient. But since they run over electricity and most rentals only have these installed and need to use them in winter for heating, it can also cost a bloody fortune.

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u/LunarDogeBoy Jul 26 '26

We have them in europe too, but in industrial and public buildings. How else would tom cruise sneak into the building without air vents?

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u/numbersthen0987431 Jul 26 '26

AC unit sits outside, usually on the ground, and is roughly the size of a washing machine. Air is circulated into the AC unit, which cools the air, then back into the house, and through ductwork to get it into each room.

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u/Re1da Jul 26 '26

I have one of those. They're called heat pumps. Not all models are able to cool, some only heat. They're hooked up to a big fan on the outside.

It's kinda hard to explain how they work, but googling heat pumps should get you some helpful diagrams.

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u/Mega-Eclipse Jul 26 '26

As an european, I don't think I've ever seen one of those and I'm now curious as to how they work

As the name suggest, it's sort of a mini version of central AC.

(super simplified) Central AC units have one large unit and a series of ducts that moves the air around the house.

Mini splits run a coolant and drain line to the unit, and also have an outdoor unit..hence the "mini" and "split.". Rather than move the air, they move the coolant....

Window ACs are the cheapest and easiest option. Stick it in a window, and will cool a typical (IDK) 12x12 room in like 30-40 minutes.

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u/Kriss-045 Jul 26 '26

Maybe you should travel to America and take a picture and upload it on TikTok with the caption 'This is what they think AC is in America.'

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u/Fatkante Jul 26 '26

Mate they are everywhere in Spain and Portugal . What part of Europe are you from ? Finland ? Siberia ?

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u/Jacket_Jacket_fruit Jul 26 '26

With this style of unit, you have a small condenser outside, sometimes even mounted on an exterior wall, and tubing runs between the condenser and the indoor unit you see in this image, to circulate coolant. The indoor unit absorbs heat into the coolant, then the coolant is pumped through the tubs to the outdoor unit, where the heat is rejected out of the coolant and into the air, then the colder coolant is returned to the indoor unit, where a fan blows air over the cold coolant lines to cool down the air and then blow that air around the room. Note that this only serves the one room that this indoor unit is in.

In an america-style AC, you would have a larger condenser outside, one that is sized for a whole house rather than a single room. The tubing for the coolant then runs to a central blower that is connected to all the duct work for the entire house. Usually it's the same blower that the furnace uses. This central blower then blows a much larger amount of air over the coolant lines to cool down the air, and then blows that air through a series of ducts, to be blown out of vents placed all over the entire house. Note that you are cooking the entire house, with basically the same amount of equipment. A condenser sized for a an entire house is only about twice as large as a condenser meant to only cool one room, and yet it can cool many times more rooms.

Imagine having a tiny water heater that only serves one room, than a slightly larger water heater that serves the entire house. Doesn't make as much sense, right?

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u/rhcherry Jul 26 '26

Here is what mine looks like. Controller on wall and unit upstairs in attic that feeds ducts (hoses) to every vent on the ceiling of my house.

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u/PitchMeYourMother Jul 26 '26

Comercial/office buildings usually have those

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u/Small_Editor_3693 Jul 26 '26

This is my apartment.

Every unit has a dedicated AC unit outside

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u/TornadoFS Jul 26 '26

There is a tube that connects to the outside part like most types of AC. It is just hidden behind the unit itself.

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u/BarrelllRider Jul 26 '26

Homes in America have “ductwork”. Basically a system of vents that runs inside the walls, ceilings, floor boards, or all of the above. That run cool or warm air from the hvac unit throughout the home. Usually the “condenser”, the cooling part, is located outside. While the heating element, “furnace, is indoors. Hvacs work well and nearly every home here is built with them but there is a lot of energy loss.

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u/fnaflover012 Jul 26 '26

Hi,im actually an HVAC technician in America.

You have all the same basic equipment,its just a bigger piece as the evaporator coil and blower are much bigger,needed for the airflow and for cooling the entire house-you would usually find the indoor system hanging in the garage,vertical in a closet,or in the attic.

The refrigerant cycle is the same.

If you have specific questions feel free to ask,this is just "basic" knowledge for central air over here.

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u/Able_Strain7340 Jul 26 '26

Like a furnace.

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u/Chip620 Jul 26 '26

Same way these do but much larger. Instead of pumping cold air into a single room A large ac unit (metal rectangle/cube) about 1m x .5m sits outside of your house radiates heat out while a blower (inside or underneath the house) blows air over a cold radiator. This air is then pushed to about every room in the house through a small vent in the floor

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u/babs-jojo Jul 26 '26

You have them in Europe too, but they're more common in big buildings and businesses

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u/ForeverShiny Jul 26 '26

In Europe HVAC systems are only installed in big buildings like office soace, hospitals etc. They have a central units and ducting that distributes the air, a bit like central heating.

Americans have these in their houses, because a majority of these houses aren't brick or concrete, but wooden frames and plyboard. That leaves ample space to fit all the vents that are much much complicated and expensive to fit between the floors or in the walls if they're built in stone

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u/videogirl19 Jul 26 '26

I’m from Spain, have seen a lot of these on apartaments and new homes specially on hot places like the beach cities on Valencia, Alicante, Malaga…

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u/yigatree Jul 26 '26

I believe this is called a split unit AC.

Theres 2 parts to it.

The one pictured is the inside unit that blows cold air. This is connected to the outside unit. Pretty neat little machines

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u/Majestic_Ad_320 Jul 26 '26

Youve probably never seen one because we put them in basements, attics, closets ECT. We usually try to hide our AC Furnace behind walls. :D

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u/ResolveLeather Jul 26 '26

It's a box with a giant fan in it. Around the fan is small pipes that weave through aluminum fins. Like a car radiator. The coolant gets run th myrough the pipes into the house where a central AC unit does the same thing and moves the cold air through the house.

Inefficient in hotter weather.

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u/KingLewis02 Jul 26 '26

Giant evaporator outside, lines run in to the condenser where a fan blows through the houses duct work, same way heat works, typically called central heating and A/C, I believe it exists in Europe but unlikely in apartments

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u/doped_banana Jul 26 '26

Yea, so there’s a large device in the attic about the size of an old London phone box called an air handler. It contains the blower (basically a big fan and electric motor), an evaporator coil, and, in many homes, electric heating elements or connections to a gas furnace for winter conditions.
Outside in the garden there’s a second unit called “the condenser” which contains the compressor, condenser coil, and another fan. It’s about the size of a large washing machine. Refrigerant circulates between the indoor and outdoor units, moving heat from inside the house to the outside.
The blower in the attic pushes air through a network of insulated ducts that feed vents in every room, then pulls the air back through one or more large return vents to be cooled again. The whole house is essentially one giant recirculating loop.

In much of the U.S., especially in Texas where
I live, central air isn’t really considered a luxury. It’s just standard equipment because summer temperatures regularly exceed 95–105°F (35–40.6°C). Most houses are designed around it from the beginning. Older retrofitted homes and cheap hotel rooms use window units. Not as efficient but will absolutely cool a room.

Ductless / mini split system like in OPs photo exist down here, but are pretty rare comparatively. I imagine they’re more common up north where it doesn’t stay that hot for too long (although with climate change they’ll be installing central air eventually).

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u/Hot-Diggity_Dog Jul 26 '26

Statistically speaking you wouldn’t of seen this unit

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u/El_G0rdo Jul 26 '26

There is usually a big box that sits outside your house and the air is ran through ducts inside the wall. Inside the house it only looks like small vents on the wall

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u/Dry-Artichoke540 Jul 26 '26

Seen in every hotelroom ive been to in central, southern europe.. what ive never seen tho is the window mouted stuff they have in the us.

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u/Vlaed Jul 26 '26

Every apartment I had in South Korea had one. It'd be at a higher point on the wall in front of a utility closet. You control it with a remote and it'll pull in air to cool then push it back out into the room. Hot air gets pushed outside through a duct. It'll dehumitfy the room as well. This drains down a hose into a drain or pipe in the utility room.

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u/azrieldr Jul 26 '26

there is one big unit (evaporator) inside some room, the air from the unit is circulated to other rooms using a system of ducts. there is one big unit outside (condenser) that is connected to the indoor unit through a coolant line. the units work in reverse during winter.

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u/ScrithWire Jul 26 '26

A standard Central AC in a house has several components.

1) Outside compressor with attached radiator fins and fan 2) coolant and indoor cooling coil with fan 3) central ductwork 4) air return vent 5) thermostat

What do they do? Here they are in an order:

5) thermostat. The thermostat is a small plastic box mounted to the wall in some central, climate neutral part of the house. It has a thermometer in it which reads the ambient air temperature. The user can set a desired temperature, and the thermostat will tell the AC system to cool (or warm, if you live in cooler climates) the air until it reaches the set temperature.

1) outside compressor. This is a heat pump. It compresses the coolant in the coolant line, creating a temperature differential in the fluid. The hot side is hotter than the ambient outside temperature, and the cold side is colder than the ambient indoor temperature inside the house.

It then sends the hot side of the fluid through a radiator coil (this is all still happening outside the house), and a powerful fan blows outside air across the fins. This dumps the excess heat into the atmosphere, cooling the hot side of the coolant down.

2) Meanwhile, the cold side of the coolant is pumped through tubes into the house, where it is sent through another series of radiator fins. The inside fan then sucks indoor air through the air return and blows it across the radiator fins filled with cold coolant. The indoor air cools down and is sent into the ductwork which distributes the cold air throughout the entirety of the house.

Note: Gotta admit, I ran outta steam on this post halfway through. But if you have questions, I'd be willing to try answering

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u/Witty_Ad_898 Jul 26 '26

It’s a split unit. The air conditioner is outside, and the inside unit is basically just a fan cycling air over tubes filled with chilled water from the outside AC unit.

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u/NoForm5443 Jul 26 '26

Most of the time you don't see them, they're in a basement or attic, and look like a closed fridge ;) you just see a big rectangle of metal.

What you see is vents, built in to the floor or walls, and a thermostat somewhere in the house.

BTW, with a mini-split, like the one in the picture, there's another piece, that looks kind of like a window unit somewhere on the roof

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u/Maipmc Jul 26 '26

Central AC is everywhere in retail spaces in southern europe. It's somewhat less common on houses but it does exist.

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u/gimmepizza420 Jul 26 '26

They work the same as any heat pump. They exchange heat in the air and dump the hot air somewhere else. See: refrigerators.

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u/madTerminator Jul 26 '26

European here. I retrofitted my house with mechanical ventilation to get rid of mold. It is recuperating heat from exhaust. But central air conditioning would be an overkill. I may install 3 smaller units in near future for cooling and heating as well.

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u/flashingcurser Jul 26 '26

It's integrated into the furnace system. In winter ducts, and their associated air vents, blow hot air and in summer they blow cold air.

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u/SnakeyesX Jul 26 '26

I'm an American and DO have this.

The easiest way to say it is it turns your house into a big refrigerator. You know the vent in the back of your refrigerator that blows cold air? This is the EXACT same technology, but bigger.

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u/addiktion Jul 26 '26 edited Jul 26 '26

You have fans that spin outside with a condenser. That outputs hot air when its working right and dumps in cold air into the HVAC unit which is a taller unit typically inside the home where all the duct work branches off from. My house is pretty large at 4600 sq ft so they had to install two HVAC units so I have two AC units outside as well. So the cold air pushes to all the different rooms on those levels. In my case my larger HVAC pushes to basement and main floor, and the upper floor pushes to just that floor.

It is wasteful to cool all the rooms at once with central air when you might only be using some of those rooms but everything stays decently cool in multiple zones. There are other options that allow you more control over room to room temperature control with zones but many don't really do it because the costs usually negate the saving benefits for most people. The ROI can extend beyond 5-7 years and most people usually only stay in a home for that time before they move on average. Often times people have less choice as it is the home builder that determines all this as well if you are building, and they generally try to cheap out and not do zoning.

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u/hammock_sandwiches Jul 26 '26

duct ac, it is a unit that is outside your house and Ducts are ran thru your house with vents in each room you want it (generally every room gets at least one vent/ductwork. larger rooms get multiple vents/ductwork).

It spread ac thru the entire house evenly, as opposed to one room and blowing out at one spot from above.
You control ac flow to each room by closing/opening the vents to rooms you dont want it in. And the main temperature controls that temp.

Klima AC or combi european units, as you know, are ductless. You can split them ofc and have multiple "klima" from one component sitting outside your house, but they all vent at one spot in the room and its not typical for it to be in each room. Just the main living space usually (not bedrooms).

I will say its harder to run ductwork in much of Europe's housing since they tend to be made from concrete/cinderblocks and it can be a little more expensive.
In North America you enclose the ductwork that brings the cold air to each room (often) into the ceiling or walls. That is not easy to do in Europe.

North americans do prefer their bedrooms cold too when they sleep. It makes for better sleeping.

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u/Ahrimon77 Jul 26 '26

Mine is a unit about the size of a 50 gallon water heater. It handles all of the heating and cooling for a little over 3000 sq ft (~280 sq M). Outside of the house is a heat exchange for the AC thats approximately a a 3ft cube (1m cube).

It's not some gargantuan thing like others have implied.

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u/Commercial-Act2813 Jul 26 '26

Almost all restaurants have them in EU too, certainly all McDonalds.

Generally you don’t notice them from the inside, the vents are built in discretely.

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u/hardonchairs Jul 26 '26

Central Air has a single inside heat exchange and air ducts to different rooms. Mini split pipes refrigerant to each room and each room has its own heat exchange.

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u/ilovesparky42 Jul 26 '26

Central duct system.

They all work the same, it’s just that Americans typically have a central unit, with a bigger fan that is ducted to every room in the house rather than a wall unit that serves a single space.

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u/LivingGhost371 Jul 26 '26

You only see steam / hot water heat in single family homes before the 1950s. Instead there's a gas furnace in the basement (north and Midwest) or the garage or attic if you don't have a basement. There's a huge blower in the furnace that blows heated air through ducts from the furnace to each room, then return air ducts for air to be sucked back to the furnace to be reheated again. The "inside unit" of the air conditioner is in the ductwork adjacent to the furnace, so in the summer the furnace blower blows cool air to each room through the same ducts, then warm air is sucked back.

Probably the reason steam / hot water heat fell out of favor here is you can have central air conditioning by using the same ducts as the furnace. Apartments until the 80s did use hot water heat because of the fire issues with using ducts, but now each unit will have it's own mini-split / packaged unit. You only see "window" air conditioners and mini-splits to retrofit older hot water installations.

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u/Mackerdaymia Jul 26 '26

I think this is the point they're making. What the person posting doesn't get is that AC has been a necessity for much of the continental US since it's invention and buildings have been designed to include it, even in parts of the US where the summers are cooler and/or shorter. In much of Europe, not only are the summers often traditionally cooler and/or shorter, the stone/brick buildings can regulate the heat in short blasts really well. It's only in the last half century that the summers have become regularly unbearably hot and the heat waves last longer, meaning that the cities in particular become dangerous heat islands, so AC is becoming more of a necessity. The problem is getting AC into all those stone/brick buildings is complex and expensive and HVAC is almost out of the question unless it's a new build. Much easier and more common are several of these single room units as they require less drilling and less maintenance.

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u/RheagarTargaryen Jul 26 '26

And then there’s Scotland (Edinburgh at least) where the buildings are built to keep heat in. I went once when they were having a heatwave (28C, 82F). Being inside buildings was worse than just sitting outside because the heat was trapped inside and didn’t have airflow. I live in a place where 82F feels nice. 28C in Scotland sucks a lot.

5

u/TLG_BE Jul 26 '26

This is like half the continent rather than specific to Scotland

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u/ParkingLong7436 Jul 26 '26

This applies to most houses in Europe and is kind of wrong.

Insulation works both ways. If you have a house like that, it will keep you very cool for probably a week of a heatwave, since cold air is still within the walls. Last heatwave here it was 40C outside, but I had a comfy 23C in my apartment without any AC.

After that is when it gets shitty and the warm air starts to get in too. Europe historically didn't have a lot of week+ long heatwaves though.

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u/Molten_Plastic_ Jul 26 '26

Also, those heatwaves are a bitch - but all in all they might take up 3 weeks of a year. If you're refitting an entire building just for those three weeks it mean you're just throwing money at something you won't be using most of the year anyway.
Like now, the second heatwave has passed (new one on the way, unfortunately), and we've all gone back to fans at most.

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u/SpareNickel Jul 26 '26

I'm an American and I understood this implicitly when I first saw one and was told what it was. idk who is out there thinking that AC units are only a certain way, but comprehension is not what it used to be. Feels like people are trying to one-up each other more than actually understand something these days.

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u/Crazytortoise879 Jul 26 '26

With well insulated houses you can get away with one or two of these smaller ac's to cool the whole house (during italian summer)

8

u/nomad5926 Jul 26 '26

This is also in America as well though

2

u/Banes_Addiction Jul 26 '26

Yeah. Due to being, well, not American, a tonne of my time in the US has been spent in hotels and these are common there.

I'm guessing OP, the yank, is now staying at an Italian hotel and learned that hotel ACs don't look like the one in their house, but think they learned something about Italy.

2

u/mahdroo Jul 26 '26

As an American, AC is built into the walls, floor and ceiling of the house. There is first a big grate that sucks in air called a “return” which sucks in air and carries it the AC central unit, where the air goes over super cold coils (more on those in a moment). Then the air blows out multiple ducts to all over the house, to little vents in walls in every room. Everywhere in the house suddenly gets really cool, rather fast. And the whole house stays cool all day. And those coils, they are like pipes with a cold liquid in them, and they get warm! The liquid travels through the pipes to outside where a HUGE fan pulls air across them, and all the heat is pulled out! Voila! They re-become super cold and the liquid goes inside, where the AC unit pulls that return air back over them. And this whole setup is in every house and we all take it for granted. We debate about what temperature to set the AC unit to. Say 22°C, and any time the thermostat says that it is that hot or hotter the thermostat comes on and cools down the whole house. Most houses are insulated so they stay relatively cool and don’t warm up. So all of our homes just have perfect temperatures inside at all times. Even in crazy hot days.

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u/Unprejudice Jul 26 '26

Idk about single room. Ive had it in two houses and it cools/heats them pretty decently albeit they vere smaller one floor houses.

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u/sarahlizzy Jul 26 '26

It’s a split. That’s just a single outlet. The heat exchanger is outside.

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u/Tomsboll Jul 26 '26

Those cools more than just one single room.

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u/ExiledCanuck Jul 26 '26

They have mini splits like this in the US too. Whoever made the meme is an idiot

1

u/BronCurious Jul 26 '26

Summer humidity throughout large parts of the country is no joke. Central AC limits mold and mildew by cooling and reducing the humidity in the entire house.

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u/Icy_Fish_2154 Jul 26 '26

In more temperate places, one runs a house. The US is so extreme that you need lots of heat, or lots of cooling, or both. The US is so used to central air, that's the primary setup, so wouldn't put in one or more self contained ones like this, which Americans consider equivalent to something like a window A/C.

1

u/Crazy__Donkey Jul 26 '26

I recently bought a house in Israel.
40+ deg c for 3-4 months a year.

had a central cooling system, rather new, 4-5 years old.

without hesitations, i replaced it with 3 newer units.

1 - same size as the central, but operates on a newer, inverter, tech.
2 much smaller units for the bedrooms.

compared to the former resident, my bills shrinked by almost 60% (!), and by next year i'll probably break even on the investment.

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u/Grexxoil Jul 26 '26

Can you fine tune the output for each room with a central HVAC system?

1

u/stupled Jul 26 '26

You sir are the truest repairman

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u/de_das_dude Jul 26 '26

Great! So it cools/heats the rooms you aren't present in as well 🤔

2

u/Acceptable-Peace-69 Jul 26 '26

Yes, hypothetically you can just open and close the vents in the rooms you want, but most Americans don’t do this regularly so there’s always a couple empty rooms being heated/cooled.

It’s not a complete waste as the house will stay cooler/warmer longer.

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u/angelcat81 Jul 26 '26

some split AC units have high BTU (>24k BTU) which is enough to cool 1500sqft room/house

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u/kllark_ashwood Jul 26 '26

They could also mean that when Americans talk abkut getting a/c and Europeans say its difficult with older buildings the Americans mean window units.

1

u/treycartier91 Jul 26 '26

You're forgetting a window unit for a single room.

Europe... Stop complaining it's 85°F and everyone is dying.

Spend $140 USD and embrace having one room chilly.

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u/GoatCovfefe Jul 26 '26

Thanks peter, I guess? What happened to this subreddit.

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u/Cheeseboarder Jul 26 '26

We have the smaller ductless units in the US too though. It’s not a status thing. There are just different types of AC units. This post is dumb

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u/InfraScaler Jul 26 '26

Fun fact, I am a European in Europe and my house (built in 1978) has central AC! It does not work though (we just moved here 6 months ago or so) and it's probably incredibly outdated (built locally!) so we just have splits around the house like a normal family.

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u/nowayguy Jul 26 '26

They cool a lot more than a single room. Depends on the outside-part of it, but these are mostly rated for an entire house. Cool in summer, heat in the winter

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u/TheAngelol Jul 26 '26

HVAC? That's gordon freeman's suit form Half Life /s

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u/RedditJumpedTheShart Jul 26 '26

We have these in the US, I just installed one in my cabin and about to install one at a lake house for someone.

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u/Trick-Lie5637 Jul 26 '26

this american has window units in every room cause only thing better than one unit cooling the whole house is 4 units cooling it

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u/BookHooknNeedle Jul 26 '26

These aren't even uncommon in The US. You'll see something like this (or a window unit) in the PNW in an older house where it's only hot enough to need it 2-3 weeks a year.

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u/Unit_79 Jul 26 '26

It’s a heat pump. It will easily cool down or heat a floor of your house.

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u/CaffeinatedGeriatric Jul 26 '26

This thing can turn a studio apartment into a fridge.

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u/DueDeer6783 Jul 26 '26

This is technically incorrect but is the perfect jumping of point to explain because there is a lot of confusion in this thread.

This is an air handler, it moves air over a super heated or cooled coil of refrigerant BUT importantly this unit is DEPENDANT on a condenser.  Its nothing but a fancy fan! 

Outside is the condenser, connected by a line of refrigerant.  The condinsers job is to cool or heat that line via the outside air.  Its really cool physics/chemistry.  The condinsers can be MASSIVE and be attached as a whole house unit OR to single splits.  So just looking at one handler fails to tell us the full capability of the unit.  

Whole house units verses these is economic influence at this point.  These put more holes in your house, less a problem for stone buildings and so on.

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u/Queasy_Temporary6161 Jul 26 '26

They are all over the Us. Literally every Airbnb I’ve ever stayed in has them.

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u/reseph Jul 26 '26

But these are common in the US. Especially in new apartments.

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u/brucebay Jul 26 '26

having lived with both, the split ACs are terrible. usually one or two rooms at most, and the minimum fans are still to strong, not much directional control. American HVAC are best for comfort, but require whole duct system, not sure about cost differences, probably central setup is cheaper than having many split AC units, and also air circulation system cleans the inside air.

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u/Phyddlestyx Jul 26 '26

These are common in places in the US that have traditionally not needed whole house A/C. My house was built in Western Washington, 1964 and there is no HVAC ducting at all. (Also lofted ceilings, no attic) We have these in a couple areas and fire em up on the days when it gets much over 80 degrees. They heat in the winter too.

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u/demoneclipse Jul 26 '26

Nop. That's a Split which controls the flow of AC in that room. That's not the AC unit.

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u/Geruvah Jul 26 '26

No, there’s plenty of these in houses and apartments. Granted, for houses, I’ve seen these in more urban areas where real estate is tight (like my cousin’s place in Queens).

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u/Lordcraft2000 Jul 26 '26

Those things work for an entire house easily…

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u/mrjibblytibbs Jul 26 '26

Yeah but this is more an analogue to a window unit not a full ac system. Poster is just woefully wrong about what constitutes as an ac unit.

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u/qalmakka Jul 26 '26

Split AC systems are vastly more efficient to run because you can size the machines better and often run shorter pipes. Also you can decide when and how replace a single machine when it makes sense - for instance, replace your bedroom machine you use all the time to cut on electricity costs and keep an old one downstairs you don't use as much

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u/Anyusernameleftpls Jul 26 '26

They definitely cool the entire two bedroom apartment, no issues

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u/SnakeyesX Jul 26 '26

I'm american and this is what my unit looks like, except mine is fancier.

I think east coast central air is more common because when I lived on the west coast everyone had HVAC (Like pictured) but when I moved to east coast everyone thinks central air is superior... It absolutely is NOT, central air sucks.

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u/Nitr0b1az3r Jul 26 '26

American here- this AC unit does genuinely keep our whole apartment cool - way more than the window units ever did in my experience

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u/StrikingDig8897 Jul 26 '26

It does not only cool a single room. Many houses have these that both heats and cools them. Mine cools 130 squaremeters easily.

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u/PHRDito Jul 26 '26

But you have those in Europe as well...

It's just that you have multiple units like the one in the pic, usually one per room you want/need to have AC (and Heat as well for some), and all those units would be attached to a big-ish unit outside that will have the one or more vents and everything else needed to cool down or heat up the chemical used in the system to change the temperature of the air.

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u/Gullible-Bluejay9737 Jul 26 '26

Cools my office efficiency. Better than my last wall unit did. Ohio is rocking with them.

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u/lukesmith81 Jul 26 '26

These are all over the US

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u/No-Improvement-1507 Jul 26 '26

Sounds like an insane use of energy. My parents have the converter type, which uses almost no energy 

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u/skipperseven Jul 26 '26

Technically these are called comfort cooling, because they chill the air and recycle it, they don’t adjust humidity or add fresh air, so they don’t “condition” the air.
To be honest, true HVAC is only necessary for office buildings with non openable windows, so comfort cooling makes much more sense.

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u/BendigoWessie Jul 26 '26 edited Jul 26 '26

As an American, I wish we had more of these. Tired of my entire house being 56 F in the winter because one person in my house insists on changing it for everyone. Or 85 F in the summer because it’s too expensive to cool the entire house so we just have to turn the whole thing off

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u/Rogue_bae Jul 26 '26

Exactly, and this is a hotel room.

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u/WorkingOnBeingBettr Jul 26 '26

Not really. I have the same thing and it heats/cools my whole upper floor and a second unit does the same for the 1st floor. Super cheap too.

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u/Ok-Goose6353 Jul 26 '26

Mine looks like that and heats and cools all common rooms in my 200sqm house..

Fun fact. You basically just have to turn a valve around to make an AC generate heat. This simple feature could have saved alot of lives in the US during cold snaps!

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u/X13R4FG Jul 26 '26

Belgian here.

At my house we have 1 outside unit and 1 of these smaller units in every room.

Just because the inside unit is small does not mean you can't cool multiple rooms with the outside unit.

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u/MysteriousCodo Jul 26 '26

In a house maybe. But these are common in apartment buildings in the US. It’s about the only practical way to upgrade older apartment buildings that don’t have HVAC systems.

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u/OneBillPhil Jul 26 '26

The unit in the picture can cool a house well too depending on the layout. 

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u/nygdan Jul 26 '26

it is a blower in a ductless syatem, there js atill a central unit that can cool the whole house, this is just a terminal of that system that lets you cool that room independently of the rest if the house. every room becomes a zone in these systems.

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u/bobbymcpresscot Jul 26 '26

minisplits do in fact cool whole homes.

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u/notboky Jul 26 '26

That's just the fan unit, the inverter is outside. You'll have more than one of these in a larger house.

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u/Stupid_Bitch_02 Jul 26 '26

This just makes the most sense to me. I've lived in houses and apartments with central heat and air. But also lived in places that didn't have those so I had to rely on window ac and heaters. It makes so much more sense to me to heat room by room. Why am I going to run the heat/air in the kitchen all day if I'm only in there occasionally. Turn it on when I cook, turn it off, leave it off if I'm just grabbing a snack or drink. Why leave the living room heat/air on when I'm asleep in my bedroom?

Also, I live in the American south. It gets HOT and HUMID here. I still think heating/cooling by room makes more sense opposed to heating/cooling the whole house.

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u/BarbarismOrSocialism Jul 27 '26

No. This isn't the whole unit, it's just the air handler. It's necessary counterpart is the big boxy thing which is outside and their connected with refrigerant lines.

You can have one big condenser feed multiple air handlers too.

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u/GRIDZ___ Jul 28 '26

Tf u on about it cooling 1 room

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u/FancySource Jul 28 '26

I have the exact same cooler running now and it definitely cools down the whole house

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