[HN Gopher] Building my own HomeKit Thermostat
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Building my own HomeKit Thermostat
Author : frenchie4111
Score : 95 points
Date : 2020-12-27 18:06 UTC (4 hours ago)
(HTM) web link (www.staycaffeinated.com)
(TXT) w3m dump (www.staycaffeinated.com)
| bombcar wrote:
| This is ingenious (and thermostats are notoriously simple) but
| I'm surprised it was easier than just running a neutral wire for
| an Ecobee.
| gregmac wrote:
| On the topic: I've had an ecobee 3 for the past few years, and
| I'm pretty happy with it - if you're in the market I'd highly
| recommend one. Killer features are mostly from the room
| sensors:
|
| * Keep upstairs comfortable at night, main floor during the day
|
| * Auto home/away mode (based on motion). This works so well, I
| only just changed the schedule to account for working from home
| about a month ago
|
| I also like "Run fan for minimum of x minutes per hour" as it
| makes a noticeable difference on sunny days where the South
| side of the house is normally a lot warmer than the North.
|
| Other than that, the app is decent and it's easy to connect to
| Home Assistant.
|
| I have an older wifi thermostat controlling my fireplace, and a
| very useful automation I only just added turns on the furnace
| fan when the fireplace is "on" (temp set above 21) which helps
| keep the house balanced.
| wincy wrote:
| My only complaint about the ecobee is the Alexa integration
| will listen when I tell my Echo Dot to play music then I'll
| end up with the Dot playing Apple Music and the Ecobee
| playing I Heart Radio or whatever because it doesn't support
| Apple Music. So two songs playing and one on a garbage
| thermostat speaker. I wish it could just have Alexa support
| but only for thermostat stuff then ignore anything else.
| johns wrote:
| Why not turn off Alexa all together on the stat and have
| the regular Alexa control it through the integration?
| JamesSwift wrote:
| I too am pretty happy overall with it. The web portal is
| pretty bad though. Its very finicky about logging in and
| maintaining its session. The app "Just Works" for the most
| part.
| zepto wrote:
| Yeah - it's a fun project. I considered doing the same, because
| of course.
|
| However there is more than one solution for ecobee.
|
| 1. Replace the existing wiring! Probably not as hard as you
| think.
|
| 2. Use an external power supply - this is supported by ecobee.
|
| 3. There are 2 to 3 wire converters:
| https://support.ecobee.com/hc/en-us/articles/360008702251-FA...
|
| Roll your own is fun, but these options are all going to be
| quicker and result in a better solution.
| frenchie4111 wrote:
| Didn't realize external power supply was available on ecobee,
| I contacted support (before purchasing) and they only gave me
| the neutral wire suggestion.
| zepto wrote:
| Yeah - I was also misinformed by support both before and
| after purchase.
|
| They have a great resource library but their support staff
| don't seem to get enough training.
|
| Edit: I had to fish a new wire for one thermostat, and
| rewire the furnace for another. The results were well worth
| it though because of the wireless temperature and occupancy
| sensors.
| vmception wrote:
| HomeKit often times is better than the OEM's app for their own
| product.
| kitsunesoba wrote:
| It's a bit of a recurring pattern with Apple software. Good
| example is with tvOS, where streaming apps based on the
| template app that Apple provides are typically less frustrating
| and more functional than bespoke streaming apps.
|
| Similarly, on iPadOS streaming services delivered through Apple
| TV+ channels often have better quality than those delivered via
| provider apps -- this has been extremely visible going from
| watching Star Trek through the CBS TV+ channel w/4k video and
| 7.1 surround to The Expanse through the Prime Video app which
| delivers a "1080p" stream that often looks worse than Youtube
| 720p.
|
| I think the root problem with all of these examples is
| companies treating software as a checkbox when it should be
| treated as core to the product.
| thewebcount wrote:
| I don't know what it is about Amazon software, but at least
| in the Apple ecosystem, it's terrible. I downloaded the macOS
| version of the Kindle reader because I was reading a
| programming-related book. A single page turn would take
| seconds to complete on a Mac Pro. I ended up profiling it
| with Instruments. It was a QT app that they had obviously
| ported from another platform and done no performance tuning
| on. It turned out it was redrawing the page 4 or 5 times, and
| allocating and freeing something like 40MB of memory on each
| redraw. It seemed like just having a statically allocated
| 40MB buffer would have solved the problem, but who knows? It
| was pretty appalling.
|
| The ratings for their own software on their own web site show
| all the problems.[0]
|
| [0]https://www.amazon.com/Amazon-Digital-Services-LLC-
| Download/...
| frenchie4111 wrote:
| I'd be interested in seeing if products can become HomeKit
| only. Unfortunately you still sort of need your own app for
| setup, etc. It's a decently sized barrier for manufacturers,
| and their app ends up shit anyway.
| saagarjha wrote:
| You can actually set up some devices without downloading a
| manufacturer app. I did this for an iDevices thermostat I
| bought recently, although I downloaded their app later
| because the home app has no idea how to do "keep the
| temperature between this range during these hours". (The app
| is not half bad, FWIW.)
| alexwasserman wrote:
| Most the HomeKit products I've tried don't need the native
| apps, just Homekit native on the phone.
|
| Vocolinc and Wemo both are like this. In fact, the latest
| Vocolinc app has a "Homekit" mode, where it's basically just
| passthrough. Used for updating firmware only, pretty much.
|
| I recently added a new Wemo smart-plug and used Homekit, not
| the app. The plug works fine in Homekit, doesn't even appear
| in the Wemo app. The only downside is no way to update
| firmware.
|
| Biggest downside to Homekit only, is that you lose specific
| functionality a manufacturer might have. That said, I find
| Homekit to be better than the vendor stuff anyway, so stick
| with it.
| aliljet wrote:
| Honestly, if HomeKit was something that we could use in an
| operating system that wasn't owned by Apple (~70% of devices on
| the planet ride Android, to be clear), the title here would feel
| a little bit more reasonable, but alas, Apple is the truest of
| true closed ecosystems. Open doesn't look like HomeKit and those
| boycotting walled gardens should know better than to find
| themselves trapped inside Apple.
| frenchie4111 wrote:
| Sure. I'll accept that I am just complaining that I can't get
| from one walled garden to the other. From my perspective, if
| they are all walled gardens, I might-aswell choose the best
| one.
| dpeck wrote:
| It would be nice if more hardware vendors got out of their own
| way and supported HomeKit. It's not perfect, at all, but it is
| far ahead of the typical vendor provided software experience.
| vinay427 wrote:
| HomeAssistant or HomeBridge (?) work great for this. At least
| with HA, nearly every reasonably communicable smart device can
| be finagled into cooperation and HomeKit sees them all through
| a bridge. I even have a "legacy/real" home alarm system wired
| up with it along with smart switches with flashed firmware to
| avoid OEM app issues.
| LASR wrote:
| I've been running Home Assistant (https://www.home-
| assistant.io/hassio/)
|
| The default configuration has an integration for HomeKit such
| that it bridges devices that do not have dedicated support. For
| example, I can control my Google-only through my iPhone.
|
| Highly recommended, especially the appliance vm image or docker
| (hassio)
| Maximus9000 wrote:
| Does homekit automatically mean the device has better cyber
| security?
| thangalin wrote:
| A related question regarding Wi-Fi line voltage thermostats:
|
| https://iot.stackexchange.com/questions/2895/wi-fi-line-volt...
|
| The question lists a number of commercial thermostats that may be
| of interest, as well as a nod to WebThings:
|
| https://iot.mozilla.org/gateway/
| runjake wrote:
| It doesn't render on my iPad but which esp32 HomeKit library is
| the author using?
|
| I have an esp32 sensor system in my garage I'd like to add
| HomeKit functionality to.
| frenchie4111 wrote:
| This is the one [1], sorry about the link not rendering. Pretty
| simple to use, I just followed the Lightbulb example [2]
|
| [1] https://github.com/Brawrdon/esp-homekit-arduino-
| sdk?utm_sour...
|
| [2] https://github.com/espressif/esp-homekit-
| sdk/tree/master/exa...
| runjake wrote:
| So great. Thank you. I think you've saved me a bit of trouble
| with my sensor project (a chest freezer monitor).
| frenchie4111 wrote:
| Good luck. I'd love to hear how it goes
| covercash wrote:
| I've had a very good experience using one of these to provide
| HomeKit compatibility to Nest devices:
| https://www.starlinghome.io
| CharlesW wrote:
| Thanks for posting this! This looks like a fine product, and it
| led me to learn that Starling Home Hub is effectively
| "homebridge-nest[1] in a box", which is great news for
| Homebridge[2] users.
|
| [1] https://www.npmjs.com/package/homebridge-nest [2]
| https://github.com/homebridge/homebridge
| covercash wrote:
| I ran Homebridge for a while but got tired of dealing with
| maintenance. The Starling box is set-it-and-forget-it. I
| don't think I've had to access the control panel since
| installing it so it was well worth the $100 imo.
| CharlesW wrote:
| For sure, the reduced cognitive overhead is absolutely
| worth the price of admission.
|
| I need to run Homebridge anyway for a bunch of devices that
| I want to be available via Alexa and HomeKit, so for me
| there was no incremental complexity. I'm running Homebridge
| via a Docker image[1] on my NAS (using QNAP Container
| Station), with Homebridge UI to manage.
|
| [1] https://github.com/oznu/docker-homebridge
| frenchie4111 wrote:
| This is cool. It's crazy to me that this sort of thing needs to
| exist
| mattowen_uk wrote:
| Neat, this dovetails into a recent comment of mine quite nicely..
|
| https://news.ycombinator.com/item?id=25465667
| amelius wrote:
| Thermostats have been the subject of maker magazines since the
| beginning of DIY electronics, (personally) to the point it
| became boring to read another article about them. If only I
| could have guessed they had the potential to spawn a billion
| dollar industry. Anyway, just typing "DIY thermostat" into
| Google returns quite a lot of projects.
| MarkusWandel wrote:
| I've been running homemade HVAC control for 12 years now. A few
| points:
|
| 1. Have "can't fail" safeties. In my case, that's the existing
| thermostat in parallel with the relay (so that the house can't
| freeze up if my system fails) and a second extra thermostat in
| series with it (so that if it fails stuck on, things won't
| overheat too badly). The second safety thermostat can be out of
| the way, like in the basement.
|
| 2. Assuming you live in a northern area and have a furnace that's
| less than a decade old, it may well be a two-stage (i.e. high and
| low heat mode) one set up for autostaging (run on low for 5
| minutes, then fire up full blast) because the installers were too
| lazy to fish the extra wire to run a proper 2-stage thermostat.
| My homemade system has a 0.3 degree Celsius difference between
| the low and high stage cut-in, plus some hysteresis to avoid
| short cycling, and it keeps the temperature wonderfully stable
| (within 0.2 degrees of the set point) with the furnace only ever
| switching to high if you turn up the temperature (on the very
| most brutally cold winter days it might run almost continuously
| on low). At least here in Canada, installers have to leave the
| technical manual with the furnace, so you know which DIP switch
| or jumper to change to disable autostaging.
|
| 3. Mechanical thermostats have something called an "anticipator"
| which slightly warms the sensing element as the furnace runs, so
| it tends to turn off below the set point. This is to avoid
| overshoot. Digital thermostats do it in software by pulse width
| modulating the furnace enable as the temperature nears the set
| point. In my case it's completely unnecessary to code this up - I
| guess the thermostat location is just perfect - but if you do get
| overshoot, just simulate it in software.
|
| 4. AC units can be damaged by short-cycling and sure enough an
| early version of my system had a bug that caused this. Luckily I
| noticed right away. Now it's full of safeties like minimum run
| and rest times and probably much more conservative than a real
| thermostat. Longer AC run times are better for dehumidification
| anyway. I also enforce minimum run times on the furnace.
| ghaff wrote:
| >Have "can't fail" safeties.
|
| This is one reason why I've never gotten anything more complex
| than a simple Honeywell programmable thermostat. I haven't felt
| a real need but I also just don't _trust_ "smart" thermostats
| not to fail off in the winter which can be a really serious
| event if you're not around (and I normally travel a lot). There
| are other failure modes for heating of course but I absolutely
| don't want to introduce another one for no good reason.
|
| (I don't have AC.)
| jjeaff wrote:
| I have found that regular smart wifi thermostats like those
| also made by honeywell fail just fine.
|
| I had a wifi honeywell for several years and eventually the
| wifi portion died. But the rest continued to function just
| fine.
|
| If whatever you have does die in the dead of winter, you can
| always remove the thermostat and short the common and heat
| wires together.
| MarkusWandel wrote:
| You can get an old school mechanical thermostat as a
| backup. I've suffered a total frozen house disaster in a
| past place - most of the plumbing wrecked - because of a
| heat failure during the Christmas break (gas valve in that
| case though; a mechanical thermostat wouldn't have helped).
| That's what started the obsession with remote temperature
| monitoring - I was into DS18B20s before they were cool -
| and from there it was only a little bit more hacking to
| just take control as well (so I can control it over the
| internet the way I like it - ssh!)
| Normal_gaussian wrote:
| This is my bugbear. All my smart systems are 'who cares'. I
| really want security, heating, and cooking to be smart as I
| have specific use cases but I don't have the time to Engineer
| the systems how I want them. Its particularly annoying as I
| have all the skills!
| frenchie4111 wrote:
| Great tips! I am already doing the parallel with current
| thermostat (I don't trust my system at all). I will look into
| the other things as well, maybe I'll add them in my v2.
| sircastor wrote:
| I've been quite frustrated that both of the houses I've lived in
| in the past decade have used "communicating" systems, meaning
| that the products exploring this space are out of reach. HVAC
| professionals describe these systems "Ferraris" of thermostat
| control, but their remote features, API, etc are awful - I'm
| stuck with what I can only describe as a touch thermostat made by
| the lowest bidder.
| hedora wrote:
| Yeah; ours has a variable speed compressor and variable speed
| fan (it is also a heat pump). The wire protocol is a closely
| guarded trade secret from what I can tell.
|
| The manufacturer sells a custom EcoBee to work with it, but
| their own custom EcoBee can only set a few fixed speeds instead
| of variable speed.
|
| This market is ripe for disruption. Sell me something with a 30
| year warranty, and plans to wire it to a raspberry pi. I'll pay
| twice as much for that as I would for anything with a sub 20
| year warranty. Since California is close to banning new natural
| gas installations, focus on making a heat pump that'll last
| forever. Military grade limited access compressors exist and
| aren't expensive compared to having someone in Silicon Valley
| perform a house call. Also, old air conditioners regularly
| lasted 30+ years, so this is a solved problem, and the patents
| have probably expired.
|
| I'll probably buy your weird proprietary thermostat because I'm
| lazy, but if it sucks badly enough, I'll know there are decent
| third party options.
| craz8 wrote:
| My heat pump was sold as having "700 levels" (that's 30-100%
| in 0.1% increments), but the Nexia software shows unit % and
| also Level 1 or Level 2. Who knows if it's actually using the
| fine grain control I paid a lot of money for?
|
| My first thermostat also died in the first year when the
| power went out. What happens in 10 years when it's no longer
| made? I have to dump the whole system and start again?
|
| Also whole features are poorly implemented - Quiet Mode
| limits speed at night, but not until after startup (or, I
| think when defrosting)
|
| I'm a bit unhappy with Trane/Nexia at the moment and would
| absolutely not recommend
| craz8 wrote:
| I would pay good money to get access to the API my
| communicating thermostat uses - the Trane device is terrible in
| many ways that basic software updates could fix
| justinph wrote:
| This is neat. I've often thought of building my own since no
| smart thermostats support the millivolt system my 50 year old
| boiler uses.
| MarkusWandel wrote:
| You can hack it if you get access to an older furnace being
| junked. You need the 24VAC transformer and the main relay (the
| really old furnaces don't have one of course). Then the smart
| thermostat (which probably needs the parasitic power from this)
| can run off that, and your millivolt system can run off the
| relay contact closure. That said, as always, keep your existing
| thermostat paralleled to it, just in case.
| jennyyang wrote:
| I have to say that HomeKit really does a good job in unifying the
| Home IoT experience. I used to use Philips Hue exclusively, but
| the HomeKit app is just so much nicer. And since then I've
| branched out considerably, and the only unifying factor is
| HomeKit. It's great.
| frenchie4111 wrote:
| I love this, and also the fact that I can control my devices
| from control center. Not having to open an app to turn on/off
| the lights is game changing
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