Thiking about central air someday, but my 1500 SQFT, 1950s rambler in Northern Virginia still has windowshakers. Small 5000 BTU units in two bedrooms that run mostly overnight. A 6000 BTU in the rec-room that runs during the day. And a big unit in the living-room that also cools the kitchen, hallway and bathroom.
The ancient 40 year-old 11.000 BTU Sears living-room unit finally conked out three weeks ago, during a spell of 100-degree days. At the time, it was struggling to keep the living-room/kitchen area below 78. And that was only if I let it run almost constantly. Was costing about $170/month for electric. I know I probably should've replaced it years ago, but it was such a big, heavy monster that I feared permanent injury if I tried to move it. And I've been advised that some of these new Chinese window-ACs aren't exactly known for longevity.
Replaced it with a 'curbside', 15 year-old 12.000 BTU USA White-Westinghouse (Rescued four days before the Sears conked out!) which has easily managed to cool off and maintain the same area at 71-72 on the hottest days, and often doesn't need to be switched back on 'till late AM. Hoping for a big improvement on my next power-bill. And we'll see how long this AC lasts!

Happy Motoring, Mark

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DrDKW