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Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by gwbas1c on Wednesday July 29, 2026 @06:18PM (#49103825)
I don't understand why he can't just connect / disconnect the power? The thermostat is a bi-metallic strip.

Assuming the thermostat is controlling 120V AC:

1: There are plenty of cheap wireless thermostats for AC that you can buy off of Amazon. I have two, and they work great with space heaters.

2: You can use a 120V relay with those thermostats to control different voltages, amperages, ect.

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BTW, controlling the dial for min cool, max cool, ect, could increase efficiency. Max cool is only needed if the unit's been off, or it's a super-hot day.

Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by daniel5151 on Wednesday July 29, 2026 @06:24PM (#49103881)
I discuss this quite early in the writeup. There is a whole section on why a smart plug will not work here.
Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by cogman10 on Wednesday July 29, 2026 @06:34PM (#49103980)
If you are ever feeling like burning down your apartment ;), the route I'd take is buying a 5-20p extension cable, cutting it open, and splicing in a 120V switch into the middle of it. You can find a few smart switches that fit that bill for whatever relay tech you are interested. It's non-invasive for the AC unit and can be quickly removed.

There's only 3 wires to deal with as well so it's not THAT scary to make your own cable (but I'd understand why you might feel differently).

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Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by cogman10 on Thursday July 30, 2026 @12:22PM (#49112190)
> It can handle the full 15 amps of the circuit safely.

OP would need a more beefy relay for an AC unit. 20A minimum, but honestly a 30 or 40A relay would be warranted as AC units have a pretty large "spike" when they turn on which generally exceeds the amp rating of their circuit. It's short enough to not trigger a circuit breaker, but it's something to be aware of when designing things like relays.

Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by gwbas1c on Friday July 31, 2026 @04:15PM (#49128058)
I'm fairly certain those exist. The "click" that a car charger makes is a commuter (sp?) (basically a relay) connecting the car to voltage. Mine handles 40 amps.
Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by cogman10 on Wednesday July 29, 2026 @06:30PM (#49103936)
This would be the route I took, but the op was scared of the plug. If their landlord does an inspection IDK that they'd love seeing a hacked power cable.

I'd basically get something like this [1] and then put it in the middle of a patch cable.

[1] https://www.amazon.com/Aeotec-Security-controller-electricit...

Re:Turning a Dumb AC Unit Smart (Without Losing My Security ... by bdavbdav on Thursday July 30, 2026 @04:39AM (#49107412)
I had a chat with this with a friend the other day - I feel like I’m much happier to do this now I live in a dwelling on its own. I mess up, it’s my issue. You mess up in an apartment block, it’s a lot more people’s issue, who aren’t opting in to that risk.