They offer more power and control than window air conditioners, yet they’re not as complicated or expensive to install as ducted systems. Still, most ductless air conditioners require professional installation (though some DIY models are available). Check out our guides to the best window unit air conditioners and portable air conditioners. Unlike window units, mini-split systems are permanent fixtures, so carefully consider where they’ll be most efficient within your home. SEERWhile shopping for your ductless air conditioner, you may see “SEER” with a number next to it.