I want some simple functions for the H33 house:
- Energy monitoring: easy with Phisaver at the switchboard
- House off: turn off all lights (and maybe A/C, vent, etc) with a single switch
- Ventilation: run the ventilation if CO2 levels are too high
- Aircon: run aircon for x hours, via a simple push-button or similar
So, do I need a all-singing-and-dancing smart hub with tri-colour lights and internet fridge? No, because:
- Light switches are fine. I don’t need or want internet-connected lights.
- Internet fridge is a solution without a problem
- Smart-house software/hardware appears immature and likely possible point of failure
So, I think I’m looking for:
- Fail-safe design: house still works if software explodes
- Prefer open source, non-vendor-specific to avoid lock-in
- Wireless control (z-wave, wifi, bluetooth LE, etc.) of ”leaf” hardware.
- Power to “leaf” hardware from 240v (avoid seperate 5v DC transformer and usb)
- Basic ‘hub’ if required
- Maybe if “leaf” devices are wifi, no hub is required and communicate with each device via wifi-connected app.
- A handful of relays to turn three lighting circuits on/off. Sits in switchboard. Could be DIN mount. Control via a simple wall mounted on/off “soft”switch.
- A device capable of sending low-voltage signals to air-con. We can’t just hard-power-switch the aircon. The low-voltage signal turns air-con on and off. Control via soft wall-mounted push-button (one press = run aircon for one hour).
- Heat exchanger could be hard-power-switch (relay) or low-voltage signal. Control via CO2 sensor (maybe custom made). Override via similiar ‘soft’ button to air-con.
And The Winners Are…
Shelly. This seems a winner. Other options are Sonoff (cheaper, less flexible, less safe?) and millions of others. Shelly checklist:
- Lots of safety stuff and certification
- Ok ecosystem and seems to be around for a while
- Wifi so no hub required
- Good integration (MQTT, REST) for developers
- DIN mount options (“pro series”)
- I think: can do low-voltage signal for aircon
- “Plus” series based on Esp32 which I’m familiar with
Design Sketch with Shelly
DIN mounted (new) 2 channel relay – one for each lighting circuit – in switchboard.
Control: A Shelly i3 or 2.5 which have AC inputs, housed in a “Wall Switch”. This is the “master off”
Maybe a Shelly Uni (2 inputs, two potential-free outputs) at condenser? or each controller? On the indoor units is a “CN32 Remote Stop Adaptor”
Control via master off button (A/C all off on exit)
Shelly 1* at each heat exchanger to close contacts and soft power down. See next paragragh. Note hard power down is not recommended in manual. Control via seperate CO2 sensor/s and master switch.
The manual of the heat exchanger shows you can control operation via TM2 with unchanged contacts. Says “Fan runs at speed 4 in auto-vent mode”. (Bypass operation is unclear but could just ignore.)**
**(CN17 can be used to control fan speed (details vague). Also fan speed can be control via 0-10VDC signal. Bypass can be controlled too? )
*(Only Shelly 1 has dry contacts. Shelly 1P, 2P, etc have live (240v) contacts. Shelly Uni has low voltage outputs have requires a 12-30V AC/DC power supply. It might be possible to insert the uni into the HX box, and power from PCB but Shelly 1 simpler?)