How much better are dual-inverter window AC units?

April 7, 2021 12:44 PM

I have a window AC unit in my bedroom that is fairly quiet when running, but often wakes me up when the compressor kicks in. It's a small room and the current AC is somewhat oversized, which I know is part of the problem here. Will a smaller, dual-inverter unit actually help me? More details within.

The room is < 200 sqft, in an old building (i.e. not well sealed), so I guesstimate I want something in the range of 5000 - 7000 BTU. Probably closer to the latter, because I like it pretty cold at night.

The smallest dual-inverter unit that LG sells is 9000 BTU. Is this likely to be in the range where the inverter can turn the compressor down enough to run continuously, and not wake me all the time?

Or would getting a "standard" unit that's more appropriately sized be just as good?

posted by Jobst to Grab Bag (4 answers total)

I would expect an inverter-powered compressor to start very quietly compared to a standard one. My understanding is that inverters start motors gradually by controlling the voltage and frequency supplied to the motor. With a non-inverter-powered compressor motor, there's nothing else to do than throw the motor across the line and let it start all at once.

I can't find any information on the turndown ratio (meaning, how low can the compressor run) on those LG window units, but I would be surprised if it can't go down to at least 60%. (Many quality split-system inverter powered compressors can go as low as 25-35%.) That would come out to 5,400 BTU/h, and I don't think you can get window units much smaller than that.

I have never actually used or seen an inverter window AC in operation, but I think it would be a good bet for your situation.
posted by Juffo-Wup at 1:21 PM on April 7, 2021

Note: I perhaps should have said "some" not "many" quality inverter-powered split-system compressors can go down to 25 or 35%, but the edit window is past.
posted by Juffo-Wup at 1:29 PM on April 7, 2021

Best answer: I have an LG dual-inverter unit and I love it. Mine is the 9,500 BTU model. My room is a little bigger than yours, about 250 square feet. The unit starts up very quietly, cools very effectively, and does not wake me up despite it being in a window that is a couple of feet away from my head.

I used to be awaked by the ka-chunk of my previous window unit's compressor kicking in, and this replacement is probably my favorite upgrade to my bedroom.
posted by bedhead at 1:50 PM on April 7, 2021 [1 favorite]

Response by poster: Adding to this for any future searchers: I got the LG dual-inverter and it is amazing. Very quiet, smooth ramp-up as the compressor turns on, no big clunk and sudden noise. 100% recommended!
posted by Jobst at 8:35 AM on April 29, 2021 [1 favorite]