[brendawalsh]

These minisplit units are typically, at least 9k to 12k BTUs, and if it a multi-zone unit it can be 24k or more.

I have yet to see a portable AC in the US that is more than 12k btus and as quiet as a mini-split.

Mini-splits are more popular now in the US, but, for whatever reason, the US is really into ducted systems.

I never understood why putting an air duct in a hot attic and an air handler in a hot garage made any sense.

You do have me curious on traffic stats for HN by country, though.

[twblalock]

A lot of central AC installations in the USA were added to the house some time after it was built, and the heating ducts were already there, so now they are used as the AC ducts too.

[brendawalsh]

Do you have any more info about this?

I am curious about the history of residential HVAC in the US.

[twblalock]

I only really know about it in the area where I live. AC was not generally included in new construction in the San Francisco Bay Area until the 1980s or 1990s. I wouldn't be surprised if a majority of apartments in the area still didn't have AC, based on the amount of window AC units I see.

However, most homes built in this area were built central ducted heating systems since the 1950s-1960s, when there was a massive building boom. Most older homes have had central heating added as a retrofit decades ago -- even old Victorian homes. So when people upgrade to AC today, it's very common to just use the same ducts.

It's not easy to find a house with a ductless mini split AC system around here. Most homes have a single-zone central system that cools the entire house.