LWN: Comments on "A kernel developer plays with Home Assistant: case studies"

Mitsubishi heat pumps

corbet — Wed, 28 May 2025 12:47:15 +0000

The same desynchronization happens with Mitsubishi's own app too. It can lead to all kinds of surprises.

The ground floor of the house uses a central air handler, and there is an MHK2 thermostat to control it. Using HA does not rule out the use of the thermostat, but it can lead to fights over who is actually in control of the system (again, this also happens when using MItsubishi's app and HA is out of the picture). Most of the time it works reasonably well, though.

Mitsubishi heat pumps

farnz — Wed, 28 May 2025 10:43:05 +0000

They do desync from each other; the intention is that you have one remote per heat pump, and only ever control it via that remote. You have to manually resync them to each other if you have more than one remote.

Mitsubishi heat pumps

mathstuf — Wed, 28 May 2025 10:20:07 +0000

> IR remotes

> so they can easily 'desync' from whatever you set

How do the remotes not desync from each other? Or is there only one remote per function?

Mitsubishi heat pumps

AdamW — Wed, 28 May 2025 09:12:19 +0000

I don't have a conventional wall-mounted thermostat (for the heat pumps), so I couldn't tell you. Ours just came with IR remotes. Those still work fine, though they're one-way and work by sending the heat pump an entire state with each command, so they can easily 'desync' from whatever you set via HA - if you set the temp to 18 degrees via HA, then press +1 degree on the remote, it will set to 1 degree higher than whatever temp the remote last set the pump to, not 19 degrees.

Energy monitor

kpfleming — Thu, 22 May 2025 12:58:30 +0000

There's another option for this, which is 100% local (no cloud at all), but is more costly as a result: https://www.egauge.net/

This device doesn't just perform metering, but also data logging (for up to 10 years, in flash storage), and other functions. While the manufacturer doesn't provide or support an HA integration, they do offer a fully documented and supported API over WiFi/Ethernet, and there's a great third-party HA integration for it (https://github.com/neggert/hass-egauge).

This was particularly attractive to me as it means I configure the device to perform all the integrations, summations, etc. itself, and not 'lose' any of that data when HA is rebooted, has crashed, etc. I like using HA to gather and display the data, but not to compute the data, as it becomes a point of failure for the data computation.

Mitsubishi heat pumps

kpfleming — Thu, 22 May 2025 12:52:39 +0000

There is a newer component for ESPHome called mUART which supports passthrough for thermostats (MHK1 and MHK2), so that they remain operational. I'm working on a small board (and firmware) which will extend this to supporting 'hardware failsafe' so that the thermostat will remain operational even if the ESP32 has failed in some way.

mUART: https://muart-group.github.io/

Mitsubishi heat pumps

raven667 — Tue, 20 May 2025 02:31:20 +0000

That's frustrating, absent a multi vendor standard it's nice if vendors just implement a common off the shelf standard protocol which has mature diagnostics tools so it can be easily reversed and documented. In a better world vendors wouldn't be afraid to just share their protocol documentation with customers so the motivated and competent could build their own integration. While sure, most customers shouldn't be fiddling with electronics they don't understand, some portion of customers have relevant training or experience with electronics and software, and I don't know if the benefits of preventing overconfident customers from destroying their gear outweigh the inconvenience to customers who want to modify and get the most out of their purchases.

Home Assistant is great for power management

Cyberax — Mon, 19 May 2025 17:38:15 +0000

Newer heatpump-based water heaters are actually more efficient than gas heaters. As in: it's more efficient to burn the natural gas, use it to drive a turbine and generate electricity, and then use it for water heating.

Home Assistant is great for power management

knewt — Mon, 19 May 2025 17:15:36 +0000

It's located in a hall cupboard next to the front door (along with the gas & leccy meters), so *possibly* a little bit?

Home Assistant is great for power management

Wol — Mon, 19 May 2025 16:52:28 +0000

> At least it's a *much* more energy efficient unit now!

And if it's replaced the existing unit, at least the waste heat is probably warming your house (nice in winter, less so in summer).

One of the drives - aiui - for combi boilers was EU regs based on the assumption that the boiler was located in a non-living area of the house (basement, loft, whatever). Most UK boilers were in the living area - we had a back-boiler in the lounge - so much of the "wasted" energy provided extra heat in our main room ...

Cheers,
Wol

Home Assistant is great for power management

knewt — Mon, 19 May 2025 16:22:17 +0000

> If you want a boiler, it's actually very hard *not* to have a combi.

So late last year my absolutely ancient, totally energy inefficient traditional boiler failed.

Now, if I had been sorting out a replacement on my own schedule, I would almost certainly have replaced it with a combi. That was always in the plans. However, this was at a time of year where I certainly needed something quickly. And such a combi replacement would have required a *lot* of extra installation time, because there is no mains water anywhere near the boiler, and there is no (currently accessible) gas anywhere near the mains water. And I'm a mid-terrace, so can not just run pipework around from front to back.

Could have covered the extra cost, I had plenty budgeted away for an eventual boiler replacement. It was the time issue, plus getting someone in. I very quickly came to the conclusion that I would need to replace with another traditional boiler. Which was disappointing, but hey, what can you do. At least it's a *much* more energy efficient unit now! And due to being a much quicker process, I was able to get someone in less than a week after it failed. Failed on a Wednesday, was replaced the following Monday.

Home Assistant is great for power management

paulj — Mon, 19 May 2025 16:00:32 +0000

Interesting. The 2016 new-build was in a part of the UK with larger homes by default (Scotland, land is much cheaper there than England for a start), so maybe that's why. Current house is older, so it has the typical immersion heater water tank (electric, and circuit also goes past the back-boiler on the fire-place - Irish houses were typically coal/peat fire heated till around the 80s).

With domestic solar it can make a lot of sense to have reasonably decent hot water storage, so perhaps that trend away from electric water tanks will change.

Home Assistant is great for power management

Wol — Mon, 19 May 2025 15:16:01 +0000

If you want a boiler, it's actually very hard *not* to have a combi.

We had our "gas fire and back boiler" replaced shortly after moving into our current home 25 years ago, and were lucky as they were in the process of banning them. Then maybe 10 years ago when heat-pumps were "new" I had one put in, but unfortunately I think we fell foul of the cowboys, and when it broke down we couldn't get it repaired, so combi was about the only option we had.

(That broke too, and our boiler guy had disappeared, a family friend of all people, so that gave us grief, too ...)

Cheers,
Wol

Home Assistant is great for power management

excors — Mon, 19 May 2025 13:15:17 +0000

No, in the UK reportedly 80% of all gas boiler sales are combi boilers, which provide hot water on demand with no tank (https://www.gov.uk/government/consultations/raising-produ...).

I think system boilers with tanks are mainly recommended for larger homes, because a combi boiler won't have enough power to supply more than 1-2 bathrooms simultaneously, but otherwise combi boilers are preferred since they're more energy-efficient and save space. (But much less efficient than heat pumps, which do need the tank.)

Data lockdown?

aigarius — Mon, 19 May 2025 12:54:43 +0000

Thank EU, we don't have that problem over here. One quick EU GDPR request and a company *will* provide you with a data export. They know the penalties will be huge if they as much as hesitate.

Home Assistant is great for power management

paulj — Mon, 19 May 2025 10:01:41 +0000

UK and Ireland surely are still water tank? Lived in a new build in 2016 which had a big water tank, could be heated either by gas or electricity.

Home Assistant is great for power management

paulj — Mon, 19 May 2025 09:45:23 +0000

Those "smart thermostat" retro-fits for water tanks are standard installs on home solar installs over here in Ireland (and I assume UK too, cause the installers here generally source devices from the UK, and certainly one of the more popular vendors of a suite of "smart" inverters/chargers/batteries/water-heaters is UK based).

In large part because - for many years - there was no ability to resell excess solar back to the grid. So "heat your water" was pretty much the only economic use for excess domestic solar generation (ok, you could buy battery storage, but the break-even economics on that were very far-out and low-utility to me). I am still waiting for our grid operator to approve V2H - currently banned - so I can use the massive battery-on-wheels in my drive way to let me time-shift and balance excess generation over to the time of excess demand.

Home Assistant is great for power management

NAR — Mon, 19 May 2025 09:21:11 +0000

For the simple reason that every house must have a water heater anyway, and that many already have an electric one.

Water heater - yes. Water tank? Not necessarily. They take up a non-trivial amount of space and even then they have limited capacity. Also in my part of the world gas is cheaper than electricity, so people tend to use gas to make hot water.

Data lockdown?

marcH — Mon, 19 May 2025 00:17:44 +0000

> I bought a device that can do X; I expect it to be able to do X in perpetuity, period end of discussion.

When X involves any kind of cloud, that assumption would be quite naive. Cloud services come and go depending on... "where the wind blows!"

When the cloud does nothing except deploying an update that removes some features running 100% locally, then I agree it's outrageous. It's a sure way to make the tech news - or even the mainstream news sometimes.

Home Assistant is great for power management

Klaasjan — Sun, 18 May 2025 21:38:29 +0000

+1 insightful.
Now, if only I had a more modern water heater…

Mitsubishi heat pumps

Cyberax — Sun, 18 May 2025 21:00:28 +0000

That's why I said "traditional" :)

Newer "communicating thermostats" for consumer HVAC units with variable-speed drives are a mess. There are no standards, and everybody does weird proprietary stuff that inevitably results in crappy apps and vendor lock-in. And this is tragic because these units are really better in any other way, they solve the short-cycling issues, and are far more efficient overall.

Data lockdown?

smurf — Sun, 18 May 2025 20:00:30 +0000

There's also feature ownership. I bought a device that can do X; I expect it to be able to do X in perpetuity, period end of discussion. (Well, unless the thing suffers from a hardware failure.)

Yes we're not there yet, but at least Home Assistant is a base for things to get better.

Mitsubishi heat pumps

TomH — Sun, 18 May 2025 15:12:31 +0000

Does the the Faikin not work for this? https://github.com/revk/ESP32-Faikin

Stats

MortenSickel — Sun, 18 May 2025 14:15:28 +0000

In my HA setup, I am saving the data I am interested in storing in postgres with timescaledb (e.g.temperature, power usage, solar panel production, not movemenent sensors) then using grafana to display data.

Mitsubishi heat pumps

pizza — Sun, 18 May 2025 12:49:52 +0000

> Traditional thermostats are just fancy dry-contact relays.

Modern ones are not. Driven by higher efficiency standards, they are tightly integrated with the air handler(s), heat pump(s), sensor(s), and more, with multi-way handshaking over some sort of shared bus [1].

I would _love_ to replace the Daikin "smart" thermostat with something less awful to use (_very_ laggy modal touchscreen UI) but the hardwired communication is unknown, and all other control mechanisms require giving it always-on internet access, setting up a somehow even crappier mobile app, and of course signing yourself up for their cloud services.

Enough of the public API has been reverse-engineered for a basic HA plugin, but it's still utterly reliant on their cloud; the thermostat itself has no open ports and the private communications to their cloud service are encrypted so REing the private API and spoofing the server is currently not feasible. [2]

I also have a couple of cheapo Medea-derived mini-split systems in other buildings; their "cloud" stuff is differently awful [3], but with an IR blaster you can just spoof the handheld remote so full local automation is quite doable.

[1] Single pair of differential data wires with a 1.2V swing (according to installation documentations), and a max run of about 40M. Most likely a variant of RS485 or CAN.
[2] Not without cracking open a working theromostat. Literally as well as figuratively (and most likely feloniously thanks to the DMCA)
[3] No API to speak of. App effectively acts as a fancy remote control, but doesn't require handing over your contact info or any location or other identifying data.

Home Assistant is great for power management

zdzichu — Sun, 18 May 2025 11:00:46 +0000

Actually, most Europe use central heating with heat generated in cogeneration or other centralised heat plants.

Damn, I've took the bait and answered to Wol's comment :(

Home Assistant is great for power management

Wol — Sun, 18 May 2025 08:40:36 +0000

> For the simple reason that every house must have a water heater anyway, and that many already have an electric one.

Except that's a non sequitur. Just because you have a water heater, doesn't mean you can turn up the storage tempature - most European installations no longer have hot water tanks.

Pretty much all new European installations are "on demand" combi systems. Although they're now slowly being replaced by heat-pump systems, which brings back the water tank.

Cheers,
Wol.

Mitsubishi heat pumps

Cyberax — Sun, 18 May 2025 07:00:25 +0000

You can buy a regular thermostat and experiment. "Fan only" and switching between cooling/heating are common features. Only the direction and oscillation modes are somewhat unusual.

Mitsubishi heat pumps

gutschke — Sun, 18 May 2025 05:52:34 +0000

At least in the case of my heatpump, I think the thermostat is doing more than just dry contacts.

It can control fan directions or oscillation. It can heat or cool. I believe it can also do "fan only". And it knows if any other unit is currently heating/cooling. If so, it'll avoid cooling while the other unit is heating, or vice versa. I suppose there is some way that you could do this with dry contacts. But I believe it uses a radio control daughter board that then talks some slightly higher-level protocol with the actually head unit.

Mitsubishi heat pumps

Cyberax — Sun, 18 May 2025 05:48:49 +0000

Traditional thermostats are just fancy dry-contact relays. So you can trivially hook them up to GPIO pins and use them to control your board. You might need to do some wiring: resistors to limit the current, 24V power supply, etc.

I did that for my house, as I actually wanted a nice wall thermostat in a room with a "virtual zone" controlled using smart air vents.

Home Assistant is great for power management

creese — Sat, 17 May 2025 23:24:04 +0000

Rheem water heaters are very common. The esphome-econet project connect lots of Rheem water heaters to home assistant. Works great!

https://github.com/esphome-econet/esphome-econet

Home Assistant is great for power management

pizza — Sat, 17 May 2025 23:08:20 +0000

> Electricity providers should promote and subsidize devices like this (whether they rely on Home Assistant or not).

Many do promote these devices, but primarily as a way of load-shedding.

(At least in Florida, time-of-use billing is not the norm, because unless you have an electric car most of your usage will be during peak times anyway....)

Will open source win home automation too?

marcH — Sat, 17 May 2025 22:24:27 +0000

> There are not many companies that see fit to support Home-Assistant integration for their products; there are probably more that are actively hostile to it. So when a company supports this integration, it moves directly to the top of my list of candidates; that is what happened here.

That's appealing to a minority of hackers, but that's IMHO negligible for the larger market.

There are billions of people holding in their hand a device running Linux for several hours every day. Most have no idea that it is using Linux or even anything open-source (and yes I'm aware Android is becoming less open now, that's besides the point)

The reason Linux and open-source are everywhere today is only because it's the most efficient and economical way for _companies_ to reuse software, by light-years. "Look boss: no lawyer, no contract and no businessman! Direct access to maintainers and I can even "fork" and fix bugs myself, just in time for the product release."

So, is Refoss just the beginning? Will Home Assistant and open-source in general "conquer" that space like many other industries before? Note I'm here specifically _not_ asking about Tivoization, GPLv3, BSD, privacy etc. These will be interesting questions but first things first: will _any_ open-source flavor be massively adopted by this industry? There seems to be a lot of standardization work happening, that looks like a good starting point.

Data lockdown?

marcH — Sat, 17 May 2025 22:02:47 +0000

> This company recently informed me that free access to my data was coming to an end; without a payment, the app would only provide basic instantaneous data. In other words, the data generated by the solar panels, which I own, is collected by the monitoring system, which I own, and sent off to a cloud system, which I definitely do not own and which will hold my own data hostage. That, of course, is just the sort of situation I got into free software to prevent.

I see (at least) two distinct issues here and it's not clear to me what is the status of each.

On one hand, I see nothing wrong with having to pay a subscription for some _cloud services and software maintenance_, e.g.: Nabu Casa. I mean in general: specifics like having to pay for something that used to be free is pretty bad but that's a different topic. Paying for software services is one of the few ways to fund open source after all, so we can't really complain when closed-source does the same.

The "data ownership" is a different question. Is the company actively trying to block direct access to the data with some crypto? Or are they just not being helpful? The former is pretty bad, the latter much less so.

There are some interesting legal questions too. Was there anything about the data in any contract? Or was there no lawyer who cared about that aspect?

Just curious.

Home Assistant is great for power management

marcH — Sat, 17 May 2025 21:41:01 +0000

When you perform the simple energy maths, you realize "smart" water heaters like this is an incredibly cheap and effective way to perform "electricity time-shifting"; with less capacity but so much cheaper than a battery! For the simple reason that every house must have a water heater anyway, and that many already have an electric one. In the US there is at least one company (Aquanta) selling smart controllers that you can "bolt on" your existing, dumb electric heater but it does not seem very popular. Electricity providers should promote and subsidize devices like this (whether they rely on Home Assistant or not).

Mitsubishi heat pumps

gutschke — Sat, 17 May 2025 21:08:54 +0000

I looked into this a while ago, so please correct me if my information is out of date.

At the time, I was under the impression that this is an all-or-nothing solution. If you hook up HA to the heat pump, you can no longer use the conventional wall-mounted thermostat. I can see how this is something that works very well for some users. But it wouldn't work in our household. The rest of the family wants conventional controls for everything, and I fully understand that. Automation should augment these controls and not replace them.

We have managed to do this for a lot of components that are set up for automation, although it turns out that it was easier to do so without involving HA -- not that I have any objection to HA.

Long term data storage

garthy — Sat, 17 May 2025 21:05:56 +0000

On of the first things I recommend doing to people setting up home assistant is install the influxdb addon and store all your data as you never know when you many need it.

I’ve ended up using our historical consumption for prediction and then charging our battery in winter at cheaper times to use in the expensive times. (We’re on a elec tarrrifd that changes price every half an hour)

Mitsubishi heat pumps

AdamW — Sat, 17 May 2025 18:38:57 +0000

You can integrate Mitsubishi heat pumps even better with HA (and save money) by not paying for Mitsubishi's expensive network adapters at all. You just need an ESP32 connected to a specific port on the heat pump, the CN105. (This port is, usefully, pretty much always a nice easy-to-identify red color). This is the Digikey parts list:

PAP-05V-S (P/N: 455-1489-ND)
Grove 4 pin cable: A034-C (P/N: 2221-A034-C-ND)
Atoms3: C124 (P/N: 2221-C124-ND)

You have to replace the connector on one end of the cable with the PAP-05V-S 5-pin connector - this is quite easy to do with a sharp knife to lift the locking pins, no soldering required. You have to be very careful to leave pin 1 on the CN105 unused - that's 12V, which you don't want going into the Atoms3 (it will destroy it). https://casualhacker.net/post/2017-10-24-CN105_Connector has a pinout for the CN105 so you can double-triple check everything. Then you plug the 5-pin end into the CN105 and the 4-pin end into the Atoms3.

For air source pumps, you then can flash it with https://github.com/echavet/MitsubishiCN105ESPHome . There's a useful discussion at https://github.com/echavet/MitsubishiCN105ESPHome/discuss... where various folks compare notes on configs and sensors and so on. Note the first post there has a correct *picture* of how you want the 5-pin cable to look, but an *incorrect* pinout table which says pin 5 is 12V not pin 1, so don't follow the table. I based my config on fonske's - https://github.com/echavet/MitsubishiCN105ESPHome/discuss... .

Once you have all that set up, you get direct info and control of the heat pumps in HA without ever touching Mitsubishi's adapter or cloud system.

Folks in the EU with water-source heat pumps can get a pre-packaged version of all this off eBay user f1p92 , with a firmware designed for those. He was kind enough to give me the Digikey parts list instead of taking my order for international shipping, which saved me a bunch of money, so please support him!

I am suprised any Chinese company will do that.

ras — Sat, 17 May 2025 08:42:41 +0000

> AFAIK, the international connection between US and China

I'm based in Australia. China is our largest trading partner. I wasn't paying much notice, but packets flowing to and from China seemed pretty reliable - only the occasional outage. We are a long way from anywhere, so everything is flaky from time to time. The Chinese web sites didn't look much better or worse than your average from from medium sized company, which is to say usable with broken bits and odd UI choices. Occasionally you have to copy and paste Chinese into Google Translate - but that's no different to an EU site.

When supplied battery died, the supplier sent out a "technician" to install the new one. Turned out he was a Chinese student doing a working holiday in Australia. Between the two of us we got it going. Students of working holidays are common thing in Australia, and we have laws and visa's to facilitate it. You commonly meet the students in bars, restaurants, and out in the bush doing farm work. Meeting one who evidently been flown over from China on a student working visa to do battery installs was a novel experience.

I am suprised any Chinese company will do that.

PengZheng — Sat, 17 May 2025 06:25:29 +0000

> It was then I realised the commands controlling my home power setup where coming from China.

AFAIK, the international connection between US and China often suffers from 5%-10% packet loss, which may lead to latency of several seconds for TCP/QUIC connections.