The "couple a stepper motor to a shaft" API is so much better than any "smart" appliance API.
Speaking more seriously, I wish classes of appliances would expose some simple analog and digital interface pins in a standardized configuration to let users choose whatever automation or monitoring hardware they want. HVAC equipment does this with standardized thermostat terminals. I'd love to see that on other types of appliances, too.
The manufacturer's crappy "app" that will inevitably be abandoned and require keeping some old phone / tablet in good "health" lest you lose the "smart" functionality (or worse, any use of) the appliance.
Then current way of putting the "smarts" inside the appliance is just planned obsolescence and a recipe for all of us being eyeball deep in ewaste.
It always kind of blows my mind that I keep seeing "smart TVs" which have a bunch of integration options for high-end AV installations (rich people's houses, etc.) but no API that you can integrate with to just handle toggling channels/inputs/power states/volumes.
(I did get my last Sony Bravia integrated with Homekit so that I could control inputs, volume, etc. via the Home app, but that's not really what I'm looking for).
Give me an HTTPS API, require me to authenticate devices on the TV itself before it accepts their commands, and just let me do whatever. Default it to off and make it a hidden setting, but yeah just let me do the thing without having to pay tens of thousands of dollars for some professional installation to integrate with hardware I don't have and can't afford.
In the professional A/V integration world, it's normal for displays and projectors to have serial port interfaces that can be driven by commands from e.g. a Crestron controller or video switcher. Just not as much of a home/consumer thing.
Smart TVs don't exist for your convenience. They exist to track your behavior and serve you ads. If they happen to have some hackability, it's an accident or happy coincidence.
It always blows my mind why those rich people even bother with TVs. I'm not rich by any measure, but still I can afford a projector, a screen and a couple KRK monitors.
It always blows my mind what ideas people have what "rich people" have or want.
I know a few 'filthy rich' people and some of them don't even own any TV or projector, because they're totally content with a laptop screen and don't want their kids to be exposed to TVs. You will not see their wealth unless you know where to look.
Once people have money, most of them begin to think about what actually serves them and what doesn't; if you can afford anything you want, you usually become more humble and selective. There's simply no point in owning things for the sake of owning them any more. Displaying your wealth usually has far more downsides than upsides. What we see is the outliers.
That seems an overstatement. I now have one in my entire house (don't have kids).
There's a fairly large TV panel on one wall in basically a sitting room. Otherwise I just use a computer. A relative basically has TVs in every room. I guess it maybe made sense when he was rebuilding anyway but it still seems excessive to me who might sit down to watch a movie or show but doesn't have live TV.
But, then, I don't have AC either in Massachusetts.
If you are rich you have single-use rooms. Hell, even I have a sleeping room, a cat room and a hacking room. It's not that expensive. The cat room doubles as a mini-cinema.
Ambient light is dealt with having nice thick blackout drapes.
This is not some rocket science, it was done for like a hundred years.
edit: actually in my former apartment I just bought a roll-down projector screen that completely covered the window. pull down - zero ambient light even in full sunshine.
My point was it isn't as simple as projectors are better.
To be clear I only know this because I was totally going to swap to a projector once I bought a place only to realize they don't work well during the day.
Lots of people (even exceptionally wealthy ones) don't want to always have to go to the theater room to go watch something. Lots of people like having the TV on in the same way one might think about having a radio on, its not necessarily a thing they're exclusively focused on.
Sure, it has a theater room with probably an incredible projector I'd imagine. It also has a bar with a big TV behind it. It also has a game room with several TVs mounted on the walls. In both of those situations, you wouldn't really want a projection setup. A brighter TV wins out in the end.
I've seen lots of TVs mounted in outdoor living room/kitchen arrangements. They're common to find in living rooms even for people who have separate theater rooms. I've seen them mounted in garages. TVs have uses other than just pure cinematic experiences. And I say that as someone who has personally pushed TV watching to an exclusive space in my home and made a point to not have TVs everywhere. Other people like different things.
A relative likes to have TV on as ambient background. Drives me a bit crazy but, hey, I'm a guest. Also used to drive me nuts when I was on group trips with a roommate and their first reaction on entering a room was to turn the TV on.
When I had a kitchen fire, I told my electrician "no smart stuff" and he was happy to go along. (I had very little previously.) He did simplify and updated my electrical panel and switches which sort of accreted over time.
Nowadays it's surprisingly easy to vibecode replacements to some shitty OEM apps (and fix bugs while you're at it). I've had pretty good luck with BT devices, even ones that dont use standard GATTs
I don't want a "smart" washer / dryer / fridge / toaster. I want a standard interface I can build my own system around, or use someone else's that they've already built.
It's insane to me that some new construction buildings still use PTACs. Having used too many of those, this was a deal-breaker last time I was in the market for an apartment. Such a New York thing, just like how you cannot have a balcony on the 2nd floor, or how you won't find those sink garbage disposal grinders in any kitchen. But cross the Hudson toward NJ, and my understanding is that they're common. It's a combination of hyper-local regulations and economic incentives that date from god-knows-when and make American cities very unique in their quirks.
I have this exact same problem. It's really the only annoying thing about my apartment. Would absolutely pay for an off the shelf solution to this problem.
Maybe not as fun but my sun room window unit is controlled by an off the shelf $20 thermostat designed for Air Conditioners. It’s the LUX Win 100 and is date/time programmable and features a compressor lockout so it doesn’t burn out your window unit by short cycling.
If you have a favorite smart thermostat you could also wire up a receptacle with a contactor between it and a cord and a 24v AC transformer wired to the line side. This would make your window unit controllable just like a central air conditioner.
I think you could use the two shafts to align and attach the mounting bracket by drilling two holes the proper distance apart. Drilling holes is pretty easy compared to cutting straight lines and I think most people are more likely to have a drill. If you use a piece of wood, the additional thickness can help the shafts to keep the wood perpendicular. You might not need any additional fastener, and the lack of fastener could help it return to a neutral position after operation rather than migrate. Also, slowing down the stepper motor can reduce unnecessary forces and the likelihood of malfunction.
Just putty over it and get a slightly matching high-gloss or semi-gloss enamel and nobody will notice it. I've put tons of holes in things in rentals over the years and basically nobody will care as long as you restore it to like condition when you leave.
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.
---
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.
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).
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.
> The rest of this blog post is a walkthrough of a software engineer’s approach to home automation and building custom hardware, and let me tell you: both the final product, and the journey to get there, are hella jank.
IMHO it's not that bad? With the disclaimer that I'm also a software engineer who dabbles very very lightly with electronics and has no mechanical engineering expertise. But the overall approach of doing this by stepper motor seems quite defensible given the security deposit constraint. The only part that seems really janky to me is that it's not physically held in place that well as noted in this paragraph:
> Ultimately, the biggest issue is that binder clips and cardboard aren’t quite as robust of a mounting mechanism as I’d hoped they’d be… and over time, the stepper motor tends to “sag” a bit, resulting in a bit too much friction between the motor, the coupler, and the underlying knob, causing the mechanism to stall out until someone manually goes and reseats it…
Involving MQTT and HA can sometimes get frustrating too; having your AC not working properly if there's a problem on a Linux machine can suck. If this becomes a problem in practice, iirc ESPHome also has a thermostat component, and temperature sensors are really cheap and easy to wire in, so you could do it all on the microcontroller pretty easily in a low-code way. But if this part is working, no need to mess with it.
That's what I did. Just an esp32 relay board with a tiny screen and a knob. Then I put more esp32 sensors in each room to get individual temps, with HA logic to select which room the thermostat pays attention to. If HA dies for some reason it falls back to a local control and I'm back to the same situation as before, a thermostat that only pays attention to the temperature in the hallway it's installed in. All the boards were flashed with ESPHome.
It does feel hella jank, but it's pretty obvious from the tone of the text that the author is fully aware of that. He went through every available option in order from reasonable to jank and this is the first one that worked.
There's nothing wrong with jank as long as it's not going to burn your house down the way some of his other rejected ideas would have.
I've wired ESP32s into all my old heat pump units using ESPHome. They are more reliable and more responsive than the $400 dongle they sold with newer units.
As a renter myself, I get the author's pain. I ended up just installing this non destructive retrofit switch for most of my home automation + smart bulbs.
> Imprecisely yeet the stepper motor all the way left/right, toggling the target temp between “really really hot” or “really really cold”
> Option 2 certainly is the “jankier” of the two options, given that it relies on a second-order property (target temp) to power the unit on/off… but hey - whatever’s easier, right?
Isn't this basically how a thermostat works? I.e. there is a component that is binary on/off, and a thermometer is used to decide to switch on or off.
I was in a similar situation with my apartment PTAC unit, but mine has thermostat terminals — I would not be surprised if this one does too. I was able to hook up an Ecobee thermostat, with the downside being that it's way more expensive than OP's solution.
I don't get how so many large buildings in NYC and Beijing (two cities that I've personally visited) use independent little AC units like the PTAC or minisplit types. A couple per apartment, peppered over the outer walls. Engineers intuition says surely a large central unit would be more efficient and effective.
Is it because of personal ownership reasons? Counterintuitive physics? Heat dissipation limitations on the roof?
There are no air ducts to move air between the units. They are old brick buildings and retrofitting central air you might as well tear down and rebuild a lot of the time.
Which of course means they should use heat pumps, since the copper lines don't need nearly as much room (I suppose you'd still have to put a drywall wall in front of one brick wall potentially). Even just putting a bunch of mini-splits on the roof (instead of individual window AC units) would be an improvement, seems like.
I had the option to buy a “central” unit or several mini splits for my apartment. I chose several mini splits. The main reason is that they can fail independently, so I’m not stuck in an apartment that is hot everywhere.
But I think the main reason is that in places without central AC, people tend to want to incrementally upgrade. For example, you might get a mini split just for your bedroom, because that’s the room you require the most comfort during the hot days. Then when you start getting used to the comfort of the AC in the bedroom, you’ll want one in the living room. And so on.
OT: I'm looking for some way to control my AC via Infrared. I have a few pretty standard AC units with IR remotes. The ones with a display on it, that just transmit all the settings on the remote via IR on every button press.
Some device I can mount in proximity, that controls the AC, but preferably also has a temperature and humidity sensor included.
that's a fun project. i'd be a little concerned about the servos failing to fully switch the switches or placing wear on them, maybe a dangerous failure mode where it is switched into and left in an in-between state unattended that could lead to a fire hazard.
you can buy smart outlets with the correct connector, just look for 20A versions. (honeywell, at a minimum, sells one).
The lack of feedback from the AC unit makes using a switched outlet potentially problematic. You really need to know the state of the compressor cycling before you go mucking with turning it on and off. (At least this was the case with the refrigeration compressors I am familiar with from my youth.) A current sensor could provide feedback but that goes beyond a regular smart switch.
i don't think that's true. i still have a thinkeco ac modlet that coned sent me years ago as part of some kind of "make your ac smart" promotion.
if you turn those knobs to the off position while the compressor is running, does it actually go into some kind of orderly shutdown or does it abruptly cut power to the compressor?
I don't think its the shutdown that's the problem but the restart. If I fiddle with the thermostat on my fridge, it turns off in one direction, but if I turn it all the opposite way it won't come back on for a few minutes. I think this is the relevant interlock. Something about letting pressure equalize.
High head pressure on startup is the problem I'm thinking of. Generally there is a delay after shutdown and a lockout on restart until the head pressure is lower. In the old refrigeration compressors I am familiar with there was an electromechanical timer to facilitate this lockout.
The wiring diagram for this article seems to reflect it would be a hard shutdown. Most HVAC systems I have interacted with have zero problems with a sudden power loss. The only potential issue is bringing the compressor back up too quickly on the other side. You could easily control for this if you were switching the whole unit using software.
I have to say. Nice work. I spent years wanting to build something like this to integrate to these systems. I never did but have spent years thinking about this. So, nice work and really appreciate your motivation.
Assuming running a dual hose inverter portable AC isn't against the lease agreement it would probably pay for itself based on the power usage. Pretty neat hack regardless.
Why? A dual-hose portable is more efficient than a single-hose, but a PTAC should (in theory) be more efficient (and possibly quieter) on account of having the heat-emitting side of the cooling loop outside of the living space, which is closer to the ideal split system - though I suppose that advantage could be undermined by the unit's age and condition.
Another option would be to install a smart timer in the outlet. However, you need to ensure that the heat won't automatically go on when the device is turned off, and sometimes the outlets are non-standard formats.
The "couple a stepper motor to a shaft" API is so much better than any "smart" appliance API.
Speaking more seriously, I wish classes of appliances would expose some simple analog and digital interface pins in a standardized configuration to let users choose whatever automation or monitoring hardware they want. HVAC equipment does this with standardized thermostat terminals. I'd love to see that on other types of appliances, too.
The manufacturer's crappy "app" that will inevitably be abandoned and require keeping some old phone / tablet in good "health" lest you lose the "smart" functionality (or worse, any use of) the appliance.
Then current way of putting the "smarts" inside the appliance is just planned obsolescence and a recipe for all of us being eyeball deep in ewaste.
It always kind of blows my mind that I keep seeing "smart TVs" which have a bunch of integration options for high-end AV installations (rich people's houses, etc.) but no API that you can integrate with to just handle toggling channels/inputs/power states/volumes.
(I did get my last Sony Bravia integrated with Homekit so that I could control inputs, volume, etc. via the Home app, but that's not really what I'm looking for).
Give me an HTTPS API, require me to authenticate devices on the TV itself before it accepts their commands, and just let me do whatever. Default it to off and make it a hidden setting, but yeah just let me do the thing without having to pay tens of thousands of dollars for some professional installation to integrate with hardware I don't have and can't afford.
I think the standard control for TV is the RS-232C port on the TV.
https://community.home-assistant.io/t/serial-projector-contr... from a quick search.
[delayed]
HDMI CEC could do something similar as well.
In the professional A/V integration world, it's normal for displays and projectors to have serial port interfaces that can be driven by commands from e.g. a Crestron controller or video switcher. Just not as much of a home/consumer thing.
Smart TVs don't exist for your convenience. They exist to track your behavior and serve you ads. If they happen to have some hackability, it's an accident or happy coincidence.
It always blows my mind why those rich people even bother with TVs. I'm not rich by any measure, but still I can afford a projector, a screen and a couple KRK monitors.
It always blows my mind what ideas people have what "rich people" have or want.
I know a few 'filthy rich' people and some of them don't even own any TV or projector, because they're totally content with a laptop screen and don't want their kids to be exposed to TVs. You will not see their wealth unless you know where to look.
Once people have money, most of them begin to think about what actually serves them and what doesn't; if you can afford anything you want, you usually become more humble and selective. There's simply no point in owning things for the sake of owning them any more. Displaying your wealth usually has far more downsides than upsides. What we see is the outliers.
Truly rich people do not have TVs.
Or if they do own a ultra high end TV like a C Seed N1 they hide them away inconspicuously.
https://www.cseed.com/en/indoor-tv/c-seed-n1-tv.html
It is like eating cheap and nasty junk. If you are rich you avoid it or eat it discreetly...Or your acquaintances laugh at you.
If you want slightly more affordable (they have prices listed - starting at £6k for a 48" TV) there's also Bang & Olufsen:
https://www.bang-olufsen.com/en/gb/televisions
Multi use rooms require TVs.
Projectors cannot handle ambient light without being a fire hazard.
>Multi use rooms require TVs
That seems an overstatement. I now have one in my entire house (don't have kids).
There's a fairly large TV panel on one wall in basically a sitting room. Otherwise I just use a computer. A relative basically has TVs in every room. I guess it maybe made sense when he was rebuilding anyway but it still seems excessive to me who might sit down to watch a movie or show but doesn't have live TV.
But, then, I don't have AC either in Massachusetts.
I was responding to projectors...
If you are rich you have single-use rooms. Hell, even I have a sleeping room, a cat room and a hacking room. It's not that expensive. The cat room doubles as a mini-cinema.
Ambient light is dealt with having nice thick blackout drapes.
This is not some rocket science, it was done for like a hundred years.
edit: actually in my former apartment I just bought a roll-down projector screen that completely covered the window. pull down - zero ambient light even in full sunshine.
My point was it isn't as simple as projectors are better.
To be clear I only know this because I was totally going to swap to a projector once I bought a place only to realize they don't work well during the day.
Lots of people (even exceptionally wealthy ones) don't want to always have to go to the theater room to go watch something. Lots of people like having the TV on in the same way one might think about having a radio on, its not necessarily a thing they're exclusively focused on.
Take a look at this house:
https://www.zillow.com/homedetails/5619-Walnut-Hill-Ln-Dalla...?
Sure, it has a theater room with probably an incredible projector I'd imagine. It also has a bar with a big TV behind it. It also has a game room with several TVs mounted on the walls. In both of those situations, you wouldn't really want a projection setup. A brighter TV wins out in the end.
I've seen lots of TVs mounted in outdoor living room/kitchen arrangements. They're common to find in living rooms even for people who have separate theater rooms. I've seen them mounted in garages. TVs have uses other than just pure cinematic experiences. And I say that as someone who has personally pushed TV watching to an exclusive space in my home and made a point to not have TVs everywhere. Other people like different things.
A relative likes to have TV on as ambient background. Drives me a bit crazy but, hey, I'm a guest. Also used to drive me nuts when I was on group trips with a roommate and their first reaction on entering a room was to turn the TV on.
When I had a kitchen fire, I told my electrician "no smart stuff" and he was happy to go along. (I had very little previously.) He did simplify and updated my electrical panel and switches which sort of accreted over time.
Many smart meters have an LED that blinks every time you consume a watt-hour.
Nowadays it's surprisingly easy to vibecode replacements to some shitty OEM apps (and fix bugs while you're at it). I've had pretty good luck with BT devices, even ones that dont use standard GATTs
Exactly.
I don't want a "smart" washer / dryer / fridge / toaster. I want a standard interface I can build my own system around, or use someone else's that they've already built.
I wish lock-in was as taboo as medieval Christian attitudes towards usury.
But weren't medieval Christian attitudes towards usury a good thing?
I guess usury is analogous to lock-in in your parent comment, not the Christian attitudes.
wouldn't treating lock-in as taboo be a good thing?
https://esphome.io/ would make the software side of this a 10 minute job
This, I'm very surprised they didn't go with it.
It's insane to me that some new construction buildings still use PTACs. Having used too many of those, this was a deal-breaker last time I was in the market for an apartment. Such a New York thing, just like how you cannot have a balcony on the 2nd floor, or how you won't find those sink garbage disposal grinders in any kitchen. But cross the Hudson toward NJ, and my understanding is that they're common. It's a combination of hyper-local regulations and economic incentives that date from god-knows-when and make American cities very unique in their quirks.
I have this exact same problem. It's really the only annoying thing about my apartment. Would absolutely pay for an off the shelf solution to this problem.
Maybe not as fun but my sun room window unit is controlled by an off the shelf $20 thermostat designed for Air Conditioners. It’s the LUX Win 100 and is date/time programmable and features a compressor lockout so it doesn’t burn out your window unit by short cycling.
If you have a favorite smart thermostat you could also wire up a receptacle with a contactor between it and a cord and a 24v AC transformer wired to the line side. This would make your window unit controllable just like a central air conditioner.
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 think you could use the two shafts to align and attach the mounting bracket by drilling two holes the proper distance apart. Drilling holes is pretty easy compared to cutting straight lines and I think most people are more likely to have a drill. If you use a piece of wood, the additional thickness can help the shafts to keep the wood perpendicular. You might not need any additional fastener, and the lack of fastener could help it return to a neutral position after operation rather than migrate. Also, slowing down the stepper motor can reduce unnecessary forces and the likelihood of malfunction.
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.
Just putty over it and get a slightly matching high-gloss or semi-gloss enamel and nobody will notice it. I've put tons of holes in things in rentals over the years and basically nobody will care as long as you restore it to like condition when you leave.
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.
---
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.
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).
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 can't offer praise for controlling a mechanical thermostat with a poorly-implemented software thermostat.
If this was a remote control knob it might begin to make sense, but it isn't.
A NYC apartment with a 115V PTAC is by definition the size of a shoebox, is twisting a knob twice a day really that much of a burden?
> The rest of this blog post is a walkthrough of a software engineer’s approach to home automation and building custom hardware, and let me tell you: both the final product, and the journey to get there, are hella jank.
IMHO it's not that bad? With the disclaimer that I'm also a software engineer who dabbles very very lightly with electronics and has no mechanical engineering expertise. But the overall approach of doing this by stepper motor seems quite defensible given the security deposit constraint. The only part that seems really janky to me is that it's not physically held in place that well as noted in this paragraph:
> Ultimately, the biggest issue is that binder clips and cardboard aren’t quite as robust of a mounting mechanism as I’d hoped they’d be… and over time, the stepper motor tends to “sag” a bit, resulting in a bit too much friction between the motor, the coupler, and the underlying knob, causing the mechanism to stall out until someone manually goes and reseats it…
Involving MQTT and HA can sometimes get frustrating too; having your AC not working properly if there's a problem on a Linux machine can suck. If this becomes a problem in practice, iirc ESPHome also has a thermostat component, and temperature sensors are really cheap and easy to wire in, so you could do it all on the microcontroller pretty easily in a low-code way. But if this part is working, no need to mess with it.
That's what I did. Just an esp32 relay board with a tiny screen and a knob. Then I put more esp32 sensors in each room to get individual temps, with HA logic to select which room the thermostat pays attention to. If HA dies for some reason it falls back to a local control and I'm back to the same situation as before, a thermostat that only pays attention to the temperature in the hallway it's installed in. All the boards were flashed with ESPHome.
It does feel hella jank, but it's pretty obvious from the tone of the text that the author is fully aware of that. He went through every available option in order from reasonable to jank and this is the first one that worked.
There's nothing wrong with jank as long as it's not going to burn your house down the way some of his other rejected ideas would have.
I'm curious: what other ideas did the author have, and why were they rejected? I can't find anything on their website.
I've wired ESP32s into all my old heat pump units using ESPHome. They are more reliable and more responsive than the $400 dongle they sold with newer units.
These articles, over and over again, are what have made Hacker News one of my regular go tos for amazing ideas and creative ingenuity.
As a renter myself, I get the author's pain. I ended up just installing this non destructive retrofit switch for most of my home automation + smart bulbs.
[1] https://www.thirdreality.com/products/smart-switch-gen3
> Imprecisely yeet the stepper motor all the way left/right, toggling the target temp between “really really hot” or “really really cold”
> Option 2 certainly is the “jankier” of the two options, given that it relies on a second-order property (target temp) to power the unit on/off… but hey - whatever’s easier, right?
Isn't this basically how a thermostat works? I.e. there is a component that is binary on/off, and a thermometer is used to decide to switch on or off.
I was in a similar situation with my apartment PTAC unit, but mine has thermostat terminals — I would not be surprised if this one does too. I was able to hook up an Ecobee thermostat, with the downside being that it's way more expensive than OP's solution.
30 years old PTAC has wired thermostat terminals. But I dolike OPs solution.
I don't get how so many large buildings in NYC and Beijing (two cities that I've personally visited) use independent little AC units like the PTAC or minisplit types. A couple per apartment, peppered over the outer walls. Engineers intuition says surely a large central unit would be more efficient and effective.
Is it because of personal ownership reasons? Counterintuitive physics? Heat dissipation limitations on the roof?
Can someone with more knowledge clue me in?
There are no air ducts to move air between the units. They are old brick buildings and retrofitting central air you might as well tear down and rebuild a lot of the time.
Which of course means they should use heat pumps, since the copper lines don't need nearly as much room (I suppose you'd still have to put a drywall wall in front of one brick wall potentially). Even just putting a bunch of mini-splits on the roof (instead of individual window AC units) would be an improvement, seems like.
I had the option to buy a “central” unit or several mini splits for my apartment. I chose several mini splits. The main reason is that they can fail independently, so I’m not stuck in an apartment that is hot everywhere.
But I think the main reason is that in places without central AC, people tend to want to incrementally upgrade. For example, you might get a mini split just for your bedroom, because that’s the room you require the most comfort during the hot days. Then when you start getting used to the comfort of the AC in the bedroom, you’ll want one in the living room. And so on.
OT: I'm looking for some way to control my AC via Infrared. I have a few pretty standard AC units with IR remotes. The ones with a display on it, that just transmit all the settings on the remote via IR on every button press.
Some device I can mount in proximity, that controls the AC, but preferably also has a temperature and humidity sensor included.
Some ACs have UART interfaces inside that can be fairly easily hooked up to an esp32.
You could also buy an IR transmitter module from AliExpress and add a temperature/humidity sensor chip on I2C like an SHT41.
I use http://getmysa.com for this. they have their own app and scheduling, but i just automate mine via homeassistant
This doesn't look like it can control the AC unit via infrared. How did you solve that part?
They have a version for mini-splits that is an ir blaster.
You need to 3D print a bracket. That's what will give you the last 10-20%.
that's a fun project. i'd be a little concerned about the servos failing to fully switch the switches or placing wear on them, maybe a dangerous failure mode where it is switched into and left in an in-between state unattended that could lead to a fire hazard.
you can buy smart outlets with the correct connector, just look for 20A versions. (honeywell, at a minimum, sells one).
https://prod-edam.honeywell.com/content/dam/honeywell-edam/h...
The lack of feedback from the AC unit makes using a switched outlet potentially problematic. You really need to know the state of the compressor cycling before you go mucking with turning it on and off. (At least this was the case with the refrigeration compressors I am familiar with from my youth.) A current sensor could provide feedback but that goes beyond a regular smart switch.
i don't think that's true. i still have a thinkeco ac modlet that coned sent me years ago as part of some kind of "make your ac smart" promotion.
if you turn those knobs to the off position while the compressor is running, does it actually go into some kind of orderly shutdown or does it abruptly cut power to the compressor?
I don't think its the shutdown that's the problem but the restart. If I fiddle with the thermostat on my fridge, it turns off in one direction, but if I turn it all the opposite way it won't come back on for a few minutes. I think this is the relevant interlock. Something about letting pressure equalize.
High head pressure on startup is the problem I'm thinking of. Generally there is a delay after shutdown and a lockout on restart until the head pressure is lower. In the old refrigeration compressors I am familiar with there was an electromechanical timer to facilitate this lockout.
The wiring diagram for this article seems to reflect it would be a hard shutdown. Most HVAC systems I have interacted with have zero problems with a sudden power loss. The only potential issue is bringing the compressor back up too quickly on the other side. You could easily control for this if you were switching the whole unit using software.
I have to say. Nice work. I spent years wanting to build something like this to integrate to these systems. I never did but have spent years thinking about this. So, nice work and really appreciate your motivation.
Assuming running a dual hose inverter portable AC isn't against the lease agreement it would probably pay for itself based on the power usage. Pretty neat hack regardless.
Why? A dual-hose portable is more efficient than a single-hose, but a PTAC should (in theory) be more efficient (and possibly quieter) on account of having the heat-emitting side of the cooling loop outside of the living space, which is closer to the ideal split system - though I suppose that advantage could be undermined by the unit's age and condition.
Portable ACs are generally less efficient than regular window ACs and PTAC units since the compressor is inside the room.
Yes, except for dual hose inverter ones.
There are also portable split systems like Midea Portasplit.
Oh, hey, I'm the author!
Happy to answer any questions :)
I'm pretty sure doing janky things to the AC you don't own is a lease violation.
I'd gladly let them keep the security deposit so that evil companies like RealPage don't blacklist me.
You have to learn to ignore what the rules say and go after the practical reality. How will the landlord know you did this? They won't.
Another option would be to install a smart timer in the outlet. However, you need to ensure that the heat won't automatically go on when the device is turned off, and sometimes the outlets are non-standard formats.
TFA mentions this.
Hey Siri, can I afford a home loan?
You’ll need to unlock your iPhone for that.
Always a latch. That's key.