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Comment by gwbas1c | Hacker News Reader

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.

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I discuss this quite early in the writeup. There is a whole section on why a smart plug will not work here.

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).

I skimmed that.

First, I'm not referring to a smart plug. I'm referring to a thermostat-controlled plug. You were afraid that it would rapidly turn the AC on and off, which would burn out the motor.

They don't do that. Mine (when I use them with a heater) run it for a few minutes, then turn it off for awhile. They don't rapidly turn the heater on and off. I assume it's the same way when run in cooling mode.

The people who make them aren't stupid.

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WRT a rely: They are safe, you just need to look at the rating for the load. (The point of a relay is to switch a high current / voltage load.) I use an industrial one for an outdoor outlet: It can handle the full 15 amps of the circuit safely. (I use it to adapt a smart switch that can only handle light loads, including a relay.)

> 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.

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.

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...

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.

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