Normal wiring is terrible, though, since it only supports turning the equipment on & off. If you have a variable-speed fan and variable-speed pumps, it would be nice for the thermostat to throttle those based on the load, but it can't.

If this company has a solution for variable-speed equipment, the best thing they can do is publish an open standard. Suppose the thermostat talks to the equipment over CAN bus, for instance, using a well-documented protocol. If they go out of business, anybody can hack together a compatible aftermarket thermostat.

A lot of solar equipment is already going this way, with batteries talking to inverters over open CAN bus protocols. As one of the biggest energy loads, the HVAC equipment should get in the game too.

What do you mean? There are variable speed furnaces that can be controlled via a normal thermostat and a 4-wire thermostat setup. Like you said, though, there's no open standard so that can be an issue, but it's standard wiring.

https://www.pickhvac.com/thermostat/ (halfway down - "Communicating HVAC System")

https://www.pickhvac.com/central-air-conditioner/extras/comm... (deeper dive into Communicating vs Non-Communicating HVAC systems)

Well, that just makes it worse! OP strongly implies that there is no good variable-speed solution, but if the industry already has an assortment of products, what exactly are they even selling?!

I think you have to go thru a licensed HVAC installer to get an inverter system. These guys are DTC.

I think you're misreading the OP slightly. There's no cross-compatible system for variable equipment, which is why the OP says you can't use variable speed equipment with Nest. Nest is basically a really fancy switch only. To use variable speed equipment, you have to use your manufacturer's proprietary system. I'm not positive this is right, but I'm pretty sure it's backed up by https://www.pickhvac.com/central-air-conditioner/extras/comm...

So basically, the premise of this product is that the proprietary system they design will be nicer than the proprietary systems HVAC manufacturer's design. That's probably true, but as an owner of a Carrier proprietary system, it's totally fine.

The issue isn't that an open standard for fully variable speed isn't possible, the issue is that nearly all of the manufacturers to date have considered this proprietary (as they want to own the entire ecosystem from controls > equipment) and a purposefully boxing Nest, Ecobee, etc, out of being able to control it in order to sell more thermostats and trying to capture more value.

Only problem, their thermostats and apps really suck.

Heat pumps are basically ACs with inverters allowing them to work at partial load (i.e. 10% pr 20% or 70%). Otherwise, they are as efficient as ACs at full load.

There are few off the shelf AC thermostats that work with most heatpumps: they are usually the on/off variety.

Remotes coming with heatpumps would do the right thing, though, and there are IR blasters that can replicate those signals and integrate into your home automation system.

Huh? My Lennox basic middle America furnace already does this if I am understanding your comment correctly.

Mitsubishi heat pumps, and most others I assume, have local thermostats that communicate by remote (I assume radio waves), but do not require the cloud. This is a fine solution, as stable as wires but not tied to the cloud.

Unfortunately, they (or at least mine) communicate by IR, which is not as stable as wires – two of my rooms have very intermittent response to my IR pucks.

Maybe Europe market is ready for this.

Considering how unstable the residential electrical and internet grid is in the US (instead of being dug in, into the ground all the cables are hanging between the trees and there are constant failures), relying on that AND on the cloud for an essential service is a no-go.

the US power grid is not in any way unreliable. US residents enjoy some of the highest grid availability figures for anywhere in the world. Sure, sometimes things go horribly wrong but their system is not unreliable by design as this comment insinuates.

I live in a rural part of New England with an electricity company that everyone dislikes because it's super expensive and sometimes things go bad. Since 2010 we've had the following major outages:

* October 2011 Snow Storm - Lost power for 4 days, didn't end up being that cold

* October 2019 Thunderstorms - Lost power for 3 days, thankfully generator kept the house going

* August 2020 Tropical Storm Isaias - Caused widespread grid damage, but only lost power for 18 hours. Internet was out for 36 hours.

* August 2021 Hurricane Henri - Widespread grid damage, lost power for about 6 hours. By this point I had powerwalls. I didn't even turn down the air conditioner.

That's it - every other outage has been a few hours. And that's living in a rural area that is heavily wooded with most of the power lines above ground and often long runs close to trees. If I lived in a suburb or city those times would be even less.

The grid in the United States, despite some widespread and documented regional failures (2021 Texas, 2003 NE Blackout), is remarkably resilient.

I would say it depends on where you live. The grid in CA has (in some parts) not been reliable for 5+ years. To Chris' point below though, it's not really relevant because gas furnaces need electricity to operate, too.

A common misconception is that you can use your forced air furnace when the power is out - you can't because the blower relies on electricity to move air around. Your point on the cloud service is a good one, which is why cloud services are value-add but unnecessary for core system functionality, ie your system works if there's no internet.

In California power outages are very frequent (PG&E is now cutting off the residential power upfront, to avoid fires and associated liability).

I’ve experienced 4-5 outages last year, a couple were local, a couple were widespread. One lasted 2 days.

Fortunately I do have a small 3.2kWh battery backup power, so I can keep the refrigerator from defrosting. I do think that this is sufficient to power the air furnace as well, but I haven’t tried.

The residential internet outages also are pretty frequent, but we don’t notice these as much as power outages.

Exactly. I will not even buy a $100 remote-internet-controlled thermostat that relies on a cloud service [0], and I've looked for both my home and my shop.

I would not even consider buying the hardware that keeps my pipes from freezing if it depends on an internet connection.

I'm happy if there are non-critical OPTIONS available that use the internet (e.g., as another poster mentioned, available optimizations based on real-time elec rates, etc.), but if there is any key function that'll fail without an internet connection, that's immediate disqualification, hard nope, not looking anymore. Period, full stop, even if it is "free" as in beer.

OTOH, if OP can deliver a true stand-alone system and guarantees that it will never require a connection for any core function (as above, optional ok), then he'll have a large market.

[0] any remote-via-internet control function should be able to directly access my IP, static or transient. Not only are non-static home IPs actually quite durable in my experience, there are a variety of easy solutions to keep track of the home IP. Yes, some of those are cloud services, but they are not tied to any hardware.

Edit: That said, I'm ok with requiring wiring beyond the normal thermostat-HVAC wiring.

It's hard pass for you because you know what a cloud is. Many don't and you don't know what many know.

Counterpoint — I have an app for my Mitsubishi heat pump and use it all the time. It’s way more convenient and lets me hyper optimize my house. I actually don’t even use the physical ones at all anymore

Are you tied to the app?

Yes s/he is. Mitsubishi force you to use their Kumo Cloud controls, which are 1) expensive (a few kk) and 2) require cloud. Supposedly Mitsubishi is replacing Kumo with something else, but that just makes the problem worse.

you can get a converter to get Mitsu to work with any 24v AC controls PAC-US444CN-1, ive installed a few of them so the customer could use their existing Nest and Ecobee thermostats.

I'm a former diamond certified Mitsubishi installer

I've used the PAC-US444CN-1 (at our house) and fully native Mitsubishi thermostat/controls (at our in-laws). The converter is better than a simple 2-stage set up but is still not as good, in my experience, as the fully native one.

It has to translate a 2-stage signal into a fully modulating output, and it still seems to do a lot more on & off with high fan speeds than I would like or would be most efficient (as an aside, yes I have verified that the dip switches are in the correct position on the converters).

On the other hand, the unit at my in-laws tends to blow gently but consistently which is both more comfortable and more efficient.

spaceguillotine I'd love to hear about your experience as a former installer! Any chance for a DM?

Wat. First of all, I have Kumo Cloud and it did not cost thousands of dollars. It was a few hundred for the adapter, and then I paid an HVAC tech to install it. That's it.

Second of all, you aren't forced to use Kumo Cloud. Even though I have it, I still have a remote that operates the Split. No network or cloud required.

Mitsubishi heat pumps has a local thermostat that operates by remote, no cloud access needed, so if the app's servers go down it will still function.

No, my phone is wireless

Pretty sure they were asking if you could still access all the functionality currently provided by the app if it were to go away for some reason (who can see the future? It's not impossible Mitsubishi goes out of business or the app gets cancelled/pulled after some number of years)

If you lost your phone, would you still be able to manage the heat pump through other interfaces?

If the app wasn't updated for ${latest phone OS}, would you be be unable to upgrade the phone OS?

What is your plan if Mitsubishi cuts off access in 20 years or updates in a way that you're not comfortable with (like add advertisements to the panels)?

You can replace the thermostats with dumb versions.

>If it doesn't use the normal wiring people already have it's a hard pass from me.

Why? a real smart thermostat can just use the existing wiring for power and then use IP over Wifi or Matter/Thread to communicate. Way better than the crappy wiring in most people's houses for thermostat control.

Because HVAC in theory should outlive most other standards that have come and gone. Its totally fine to built on top of it, but using basic hard wiring to turn on/off is essential - even if just as a fallback. in 20 years the hvac should still be working, but will the wifi spec it shipped with? What about matter/thread?

Theres certainly a middleground between "must use existing old ass 2 wire setups" and "requires fancy always on cloud subscription"

Surely we could come up with a device that might require an electrician to run a few extra wires (or maybe even larger wires or something) and still run perfectly fine offline, for as long as the hardware functions, with some type of integrated manual controller. And of course this device could also have an internet option and an app and wifi for all of the fancy stuff.

I agree. Use standardized wiring and let me control it from a $100 smart thermostat that i can replace if it becomes obsolete.

If i want HomeAssistant integration, ill buy an HA-compatible thermostat.

I dont want an expensive HVAC system to be in a walled garden of its own.

You lose about 30% efficiency using "standardized wiring" with an inverter heat pump instead of a communicating thermostat, because running a heat pump at 33% power continuously instead of 100% power 20 minutes of every hour results in a COP about 30% higher.

Why do inverter heat pump need proprietary wiring? Everything I've seen indicates inverter and dual stage heat pumps can use standard wiring.

They don't need it, they just don't get all their rated efficiency, which is much higher than single-speed systems. Single-speed systems commonly have cooling efficiencies around 10-14 SEER, the Gree Sapphire is 38 SEER. If you ran it at only full power, it'd probably only be 30 SEER.

Disagree. There are a lot of advantages in being able to coordinate heating/cooling and general home electricity use based on stuff like weather forecasts, your electric company's rate tiers (including working around peak hours), when you are home or about to come home etc. Of course there should be a fallback mode where the system can work 100% offline, but being connected is definitely worth it.