Comment by sippingabonedry
2 days ago
For anyone wondering why he would ever do this, it seems to be a type of hidden mini-split system used in euro-style shoebox flats, with a super-proprietary thermostat. Wi-Fi capability is an option at additional cost, but was not purchased.
In the USA, wired thermostats tend to use standardized 24V wiring schemes, or 208V/240V for mains voltage heaters (electric heat, common on the west coast, especially in shitty apartments, central hot water/steam heating with 24V controls is more common on the east coast).
Most new construction with heat pumps are going to use similar thermostats, both because of improved efficiency since the outside unit wants to know how much heating/cooling load is being requested, and more importantly, because builders are lazy and would rather use a battery-powered wireless option than run thermostat wires.
Off the top of my head, Mitsubishi, Rheem, Lennox, and Carrier all have similar default options, with converter boxes for retrofits to 24V controls.
Is this "mini" split? This type of panels are pretty standard for office buildings in Japan. Usually networked into building management system somewhere. Most household mini splits come with an IR remote, and don't support these panels. Standalone third-party thermostats are rare.
People tend to mix the terms around a lot, but generally you'll see the manufacturers use "ducted split system" or "mini split", where mini splits are the self-contained wall or ceiling mounted units.
I live in an NYC apartment with a similar Mitsubishi ducted split system - very short run ductwork just because the apartment itself is small, but takes up way less space than traditional American-style air handlers, even the apartment sized ones. The entire air handler is suspended above my bathroom ceiling, in between the drywall and the slab above.
My system was originally installed with the 2-wire serial wall thermostat but I converted it to one of Mitsubishi's Redlink wireless units because I needed to relocate the thermostat. But since Redlink isn't wifi, and the Mitsubishi networked thermostats and cloud platform get pretty poor reviews... this project is super interesting to me.
Even for ducted systems, these proprietary controllers are the only thing you can get in Japan, and by extension places like Australia/NZ where the systems are all imported from Japan. (Europe is still largely yet to discover heat pumps, judging by reports from this past summer.)
I had this same control panel in Australia. The actual AC unit was part of the strata common property and I think somehow shared between multiple units on the floor.
FYI this kind of thermostat is actually better. American style thermostat put your HVAC system in either on or off state (basically PWM), whereas this kind of communicating thermostat can tell the system what the temperature is, so they adjust power accordingly. I do wish they have standardized protocol though.
Single stage hvac systems tend to have better performance in the max capacity cooling cases (Texas) and last significantly longer than units that rely on non-linear electronic devices.
The difference can be as extreme as 10+ years of service life. There are residential systems that were installed in the 80s and 90s that are still running fine today. The hermetically sealed scroll compressor is an engineering marvel. The electronics will generally fail before any meaningful mechanical wear is incurred.
Single stage forced air / air handlers AC systems are basically only found in North America because they are so grossly inefficient and because most people in the rest of the world realize they can save money by not having all of their rooms ran off the same system. The rest of the world runs on mini splits for that reason.
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>Single stage hvac systems tend to have better performance in the max capacity cooling cases (Texas) and last significantly longer than units that rely on non-linear electronic devices.
Why?
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The thermostat is better only because it takes advantage of the inverter modulation capabilities in the heat pump. I don't have the sense that inverter modulation is the norm for most home ducted systems, even new builds in North America.
I've only observed ductless systems like this in retrofitted, older homes in Canada. And at that point they're usually not integrated with the home's existing heating system / thermostat.
It is starting to happen in the US as well.
In some countries there are devices supporting the OpenTherm protocol: https://en.wikipedia.org/wiki/OpenTherm https://www.opentherm.eu/
Depends on your definition of better.
It's a tradeoff I'm willing to make for simple, open I/O. It's not PWM but rather a "call" for heat, cooling, or fan. If I'm refinishing the wall I can (and have) put in a $3 thermostat in its place so I don't destroy the $300 one with paint and dust.
It's also very easy to debug and repair, as I experienced on a day when the temperatures exceeded 100F and was able to execute an emergency repair myself.
If companies like Nest and Ecobee were not allowed to exist, we would all be stuck with the overwhelmingly universally overpriced, proprietary garbage the OEMs put out.