The OpenSprinkler controller

Posted Aug 26, 2023 0:30 UTC (Sat) by Cyberax (✭ supporter ✭, #52523)
In reply to: The OpenSprinkler controller by josh
Parent article: The OpenSprinkler controller

I'm designing my new house, and I've looked into the variable speed HVACs. It's depressing. Literally everything there is complete crap, with proprietary standards that sometimes require Internet connectivity to even get set up. For now, my plan is to install hydronic units with a large cold water tank to buffer the demand.

The main advantage of variable-speed units is that they can work constantly at low speed, maintaining the exact set temperature. The classic HVAC units instead turn on, overcool the house past the temperature setpoint, and then turn off. This is less efficient and also less comfortable for people.

Hydronic systems work around this by having a tank of water, that provides plenty of buffering capacity and the indoor units support variable speed. It's also easier to do zoning, you can have as many units as you need, without the need to use clunky air dampeners.

The OpenSprinkler controller

Posted Aug 27, 2023 18:01 UTC (Sun) by pwfxq (subscriber, #84695) [Link]

You might be interested in the work RevK's done with Daikin Air-Con units.

https://www.revk.uk/search/label/DAIKIN

https://www.aa.net.uk/etc/circuit-boards/pcb-faikin/

The OpenSprinkler controller

Posted Aug 31, 2023 13:27 UTC (Thu) by kpfleming (subscriber, #23250) [Link] (6 responses)

ESPHome has 'climate' components which can communicate with a number of modern HVAC systems, including Mitsubishi systems with CN105 connectors (which many have).

The OpenSprinkler controller

Posted Aug 31, 2023 16:40 UTC (Thu) by Cyberax (✭ supporter ✭, #52523) [Link] (5 responses)

I got excited, went to check it, and then got un-excited. It doesn't appear to support the variable speed units.

There are many projects that work using IR blasters, but it's not really something I'd want for an installation that should last 10-15 years.

ESPHome + Mitsubishi HVAV

Posted Sep 2, 2023 12:03 UTC (Sat) by kpfleming (subscriber, #23250) [Link] (2 responses)

The in-tree CN105-based integration is in the works: https://github.com/esphome/esphome/pull/5265

There's also an out-of-tree integration available: https://github.com/geoffdavis/esphome-mitsubishiheatpump

ESPHome + Mitsubishi HVAV

Posted Sep 2, 2023 17:13 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

It doesn't support multi-speed central units. These types of ACs don't have individual split units that are located in individual rooms, instead there's a large unit typically outside, and it delivers cold/hot air through air ducts.

These units used to have only one (or maybe two) speeds, so they could just be controlled by a simple dry contacts interface. Thermostats simply need to short a couple of contacts to call for heat/cold.

But new units can have more than 1024 speed settings, and they use proprietary protocols to communicate with thermostats. Thermostats are also pretty advanced, and they "learn" the behavior of the room they're in, so they request just enough cooling/heating to keep the room at a constant temperature. It works pretty well, but everything is proprietary.

ESPHome + Mitsubishi HVAC

Posted Sep 2, 2023 18:55 UTC (Sat) by kpfleming (subscriber, #23250) [Link]

If you're referring to the products from Mitsubishi Electric (which are the targets of the links I posted previously), they don't make systems like the ones you are referring to, where the air leaves the building and returns to it.

What they do offer, in addition to the mini-split style systems, are indoor air handlers which are connected to outdoor units which are similar to the ones used for mini-splits. Our home has two of these systems: an air handler in the attic and one in the basement, and two outdoor units handling the energy transfer with the outdoor air.

These systems do indeed use proprietary wireless thermostats, but the receiver unit for those thermostats plugs into the same CN105 connector in the air handler as it would plug into a mini-split indoor unit. The bulk of the protocol spoken over the CN105 connector has been reverse-engineered, and these ESPHome (and other) implementations can be used in place of a Mitsubishi thermostat with no loss of functionality.

As it turns out, the manufacturer's thermostats are not that intelligent (at least in the case of the MHK2), they defer all of the decision-making about fan speeds and inverter speeds to the air handler/outdoor unit combination. Many people, including me, have used ESP32s running ESPHome instead. I'm going to be experimenting with connecting both ESPHome and the MHK2 simultaneously, with the MHK2 having control but with the ability to monitor with Home Assistant (and obtain power delivery information which is not made available otherwise). Even the Mitsubishi 'cloud connection' unit also plugs into CN105.

The OpenSprinkler controller

Posted Nov 11, 2023 4:19 UTC (Sat) by Rudd-O (guest, #61155) [Link] (1 responses)

I wrote an ESPHome integration for my own variable speed AC unit via IR (ESP_01m) then puppet the AC using a PID controller. Total compatibility with Home Assistant and .3 degree accuracy — remarkable for a project which cost me $10 in parts including the wall wart to power the ESP.

The OpenSprinkler controller

Posted Nov 11, 2023 5:03 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link]

Is your unit using a variable frequency driver with analog inputs?