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Turning a dumb AC unit smart (without losing my security deposit)

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Re: Turning a dumb AC unit smart (without losing my security deposit)

#171

Post by gwbas1c »

cogman10 wrote: post #166
gwbas1c wrote: post #158

Earlier quoted context omitted.

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 peopl…

> 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.

Re: Turning a dumb AC unit smart (without losing my security deposit)

#173

Post by Reason077 »

tjoff wrote: post #149
Reason077 wrote: post #6

Instead of attaching the motor bracket with a binder clip, consider sticking it down with some sort of removable adhesive? 3M command strips should be very strong/secure, while also allowing for adjustment and will detach without residue when the time comes.

I'd never trust that it will hold and detach without residue, but that is probably my ignorance talking... I own a 3d printer which makes most of these projects look like the perfect fit for a 3d print (even when there are far simpler solutions). So that is what I'd do :)

> "I'd never trust that it will hold and detach without residue, but that is probably my ignorance talking.."

Command Strips work similarly to the adhesive that holds batteries into phones. Very strong hold in the directions that count, but pulling the tab stretches them in a way that causes their structure to collapse and release. Must have for anyone who rents a house and doesn't want to put holes in walls etc, but I've also found them to be very useful for all sorts of off-label applications.

They're strong enough to hold heavy picture frames etc on to walls, lasting for years and still detaching easily. I'd certainly trust them to secure this little motor!

Re: Turning a dumb AC unit smart (without losing my security deposit)

#174

Post by dlenski »

dn3500 wrote: post #137
Maxion wrote: post #125

Earlier quoted context omitted.

The PTAC units shown in the article look like something from the 1950s. Minisplits have been the way the world has done AC for a long long time now. It's interesting how foreign of a product it is in the US.

It uses R-22 so it's pretty old, but probably not 1950s. Maybe 1970s. R-22 was phased out starting in the 1980s, and banned in 2010 (that's in Europe, maybe later in US). When I lived in the US I tried to get a minisplit and they wanted $4000 for a medium size unit! The same one where I live now is $400 installed.

> R-22 was phased out starting in the 1980s, and banned in 2010 (that's in Europe, maybe later in US).

The situation with R-22 (better known as "Freon" in the US) seems pretty messy and confusing. https://en.wikipedia.org/wiki/Chlorodifluoromethane#Phaseout...

As far as I can tell, the import of the R-22 refrigerant itself wasn't banned until 2020.

Re: Turning a dumb AC unit smart (without losing my security deposit)

#175

Post by dlenski »

kazinator wrote: post #103

If all you need to do is replace a potentiometer with electronic control, it may be possible to do that with a vactrol. It's more invasive perhaps, but then we're not dealing with anything mechanical. A vactrol is a device which combines LED and photoresistor in one package (sealed against the leakage of light). The photoresistor has a "dark resistance" that is typically very high, like hundreds of thousands of ohms.…

> If all you need to do is replace a potentiometer with electronic control, it may be possible to do that with a vactrol. It's more invasive perhaps, but then we're not dealing with anything mechanical.

This is what I was wondering about as well.

The knobs on the unit are probably potentiometers, so it ought to be possible to replace them with a digital device of some kind, and avoid the mechanical coupling altogether.

I imagine that the author did consider this possibility, but decided that disassembling the control panel in order to replace or byypass them was just too difficult and dangerous, especially since everything is at AC line voltage as he notes in the write-up. The modern smart thermostats that I've looked inside have a clean separate between the low-voltage digital side, and the AC-line-voltage power control side… but evidently these older purely-analog devices didn't.

Re: Turning a dumb AC unit smart (without losing my security deposit)

#176

Post by itslennysfault »

prmoustache wrote: post #121
itslennysfault wrote: post #9

Earlier quoted context omitted.

I'd cut a block of wood to fit snuggly to the left of the knob, wedge it in place and screw the stepper in to that. .....or just screw into the AC unit somewhere discrete and hope no one notices.

Have you ever seen a landlord check that kind of things really? Unless you have made a mess with wires getting out looking like a fire hazard in waiting I don't know anyone who would stop at 2 tiny screw holes. Heck the landowner may not even remember the unit was not made that way in the first place.

Agreed. I've done some crazy stuff in apartments. Last place I rented I installed a projector on the ceiling and ran wires through the ceiling and walls because it'd be ugly otherwise. Also converted a ceiling light into an outlet to power it. Patched the drywall before I moved out and the landlord never needed to know.
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