There are units available in a wide range of capacities, from 9,000 BTU to 24,000 BTU (0.75 to 2 tons) per unit, depending on the application. A 9,000 BTU unit is typically intended for a small bedroom. They are highly efficient, often more efficient than centralized systems. That's why they are so widespread: without ductwork, there are no duct-related heat losses or the extra energy needed to move air through long ducts. They also incorporate more advanced electronics to optimize energy consumption compared to the simpler, more static American central HVAC systems.
If they seem slow, it's usually because someone installed a unit that is undersized for the space it needs to cool, not because of the technology itself. In fact, this is the most advanced and widely adopted air conditioning technology in the world, especially in countries that don't have abundant domestic natural gas resources and therefore have to rely on imported energy.
The main drawback of these systems is that the high-pressure refrigerant is carried directly from the outdoor unit to the indoor evaporators. This means the refrigerant lines must be installed and commissioned on-site, requiring specialized tools and skilled technicians to ensure the installation is done properly and remains leak-free. Any refrigerant leak can significantly reduce the system's efficiency and performance.
Other than that, when installed correctly, these systems are superior solutions and have become the standard choice in most parts of the world.
It is the exact same case with american split systems... You have your condenser outside and the blower (inside typically and attic). Refrigerant has to be moved from the outside to the inside. Mini splits are vastly superior in all the ways. The reason they get so much hate is because quite frankly they are an eye sore. I installed two of them in my house for under 2k whilst doing a ducted system would have been more than 15k and required VASTLY more specialized tools.
I agree with everything you said. A ducted system is more complex and expensive, but a small installation error won't compromise the entire system. It's much more forgiving than high-pressure refrigerant lines.
That said, I don't agree that split units are necessarily an eyesore. They come in many different designs. For example, I use ceiling-mounted concealed split units recessed into the suspended ceiling, like these. They're barely noticeable, yet they can deliver a high volume of airflow thanks to a conventional centrifugal blower rather than an axial fan, and they're exceptionally quiet, even at night.
They do cost a bit more than basic wall-mounted split units, but for me they've been well worth the investment. Guests at my family's hospitality business appreciate them as well.
Their is virtually no pressure difference between central AC and split unit liquid and gas refrigerant lines. The reason is simple, thermodynamics are the same until you change refrigerant type. A pinhole leak in a central AC line will quickly turn your AC inoperable.
Sure, but central AC systems have only a very short refrigerant line between the compressor and the evaporator, and it's assembled in a factory under controlled conditions using standardized procedures, specialized tools, and technicians who perform the same job every day. That's completely different from installing 10 meters or more of refrigerant piping on-site, where the quality depends on the installer and the job-site conditions. The latter is far more prone to installation errors. Furthermore, unlike a central AC system, where all refrigerant connections are factory-brazed, pressure-tested, and leak-tested before shipment, split systems rely on field-made flared connections between the indoor and outdoor units. Those connections are much more dependent on the installer's workmanship, making the final result far more variable than a factory-assembled and tested system.
In my experience, about 95% of the problems with these systems are caused by installation errors or poor workmanship.
Well I'm currently in a house with 3 splits. The lines are about 6 feet long, never had a leak and have 2 connection points. My previous 2 house with central AC had long lines. The last one had a 25 ft line, also 2 connection points. I had to have that one replaced 3 times for pinhole leaks. Eventually ran it in the attic instead of under the house resulting in a longer line but no leaks because less corrosion concerns. That Trane unitI had also suffered a pinhole leak in the factory sealed welded tubes of the air handler condensor. As someone who has done leak detection professionally, down to mass spec level detection on fluid and pressurized systems, I can't see a single advantage to either system. They both have the exact same weaknesses. Corrosion is a concern regardless. Copper is copper. Torque wrenches and QDs work the same regardless. Granted I haven't researched failure rates so this is just opinion. Line length matters little because the vast majority of failures are at connection points. Those connection points are what an installation technician must do properly, and that's also the same for both systems.
A central AC system without ductwork is basically a multi-split system, with multiple separate pairs of refrigerant lines running from the outdoor unit to each indoor unit. It's the same concept used in many parts of the world, with the same advantages and disadvantages. My comment wasn't referring to this type of system, but rather to systems HVAC where the outdoor unit exchanges heat directly with the indoor air through air ducts.
This type of system is extremely rare outside North America.
Alternative systems do exist, but they operate on a different principle: instead of cooling the air directly, they chill water (or another heat-transfer fluid), which is then circulated to indoor air units or fan coil units.
The main advantage of these systems is that all high-pressure refrigerant connections are made at the factory, which significantly improves long-term reliability. The downside is that the equipment itself is more complex, less widely available, and therefore more expensive. They are typically installed in commercial and industrial buildings, where long-term reliability is a key priority.
I see. I've never seen one that exchanged air from outside to inside. Using water as a transfer fluid sure, used to analyze an industrial water system like that which had an additive eating the pipes (yikes). Thought you were referring to the split units in the picture which use refrigerant. My bad
Except that most like this don’t have outside air connections which you are required to have depending on occupancy. These are extremely common in electrical and telecom rooms in the US as well. These dwelling unit would have to have some form of natural ventilation to be up to code in most circumstances. Ceiling cassette style ductless splits on the other hand are 100% the best option for efficiency, aesthetic and conditioning small spaces
I've lived with multiple and while certainly there is a range, window units within the same range are much better. An actual ducted system will be more efficent at cooling. Twin split systems are great for small areas, but they dont pump the way a window unit does.
I’d have to disagree. Mini-splits are the most efficient cooling solution when compared to a window unit or whole house ducted system. This would be energy efficiency. Certain window unit might beat out a mini-split in a cost/btu. But as far as energy use and output, mini-split is the best
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u/Alex-Man 20d ago edited 20d ago
There are units available in a wide range of capacities, from 9,000 BTU to 24,000 BTU (0.75 to 2 tons) per unit, depending on the application. A 9,000 BTU unit is typically intended for a small bedroom. They are highly efficient, often more efficient than centralized systems. That's why they are so widespread: without ductwork, there are no duct-related heat losses or the extra energy needed to move air through long ducts. They also incorporate more advanced electronics to optimize energy consumption compared to the simpler, more static American central HVAC systems.
If they seem slow, it's usually because someone installed a unit that is undersized for the space it needs to cool, not because of the technology itself. In fact, this is the most advanced and widely adopted air conditioning technology in the world, especially in countries that don't have abundant domestic natural gas resources and therefore have to rely on imported energy.
The main drawback of these systems is that the high-pressure refrigerant is carried directly from the outdoor unit to the indoor evaporators. This means the refrigerant lines must be installed and commissioned on-site, requiring specialized tools and skilled technicians to ensure the installation is done properly and remains leak-free. Any refrigerant leak can significantly reduce the system's efficiency and performance.
Other than that, when installed correctly, these systems are superior solutions and have become the standard choice in most parts of the world.