What choices are available for HVAC thermostats if I don’t want to use a Google Nest or some of the other similar thermostats? I want to replace our heating & air conditioning thermostat with something I can tie into Home assistant. Any suggestions/recommendations?
A thermostat is just a sensor and an actuator and a bit of logic for
Since this is in DIY corner… ; and looking at the time of your post I’m assuming you’re in Europe, you’ll need 3 things, and there’s multiple choices for each.
Sensor
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Esp01 + dht11
these small thumb sized combo of boards cost <$5 on ali express and around $5 through an amazon reseller, not very accurate -
xiaomi bluetooth sensors + esp32 as a bt-wifi bridge
e.g. one of these Xiaomi Mijia BLE Sensors — ESPHome ; use esp32 since its bluetooth is more reliable than random realtek usb bluetooth dongle, and you can plug them into a fake iphone usb charger typically -
aqara and/or other zigbee sensors
There’s cheap opensource ready to go usb zigbee dongles that work with everything, checkout zigbee2mqtt project documentation for links to supported adapters if you want to go with this. Zigbee might be nice in case you have radiators, tuya makes zigbee controlled smart radiator valves.
Actuator
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esp-01s + relay board
e.g. in case you want to control the “call for heat” line on your gas boiler when -
zigbee radiator valves
to make your heating system multi zone, you can control the radiators to need/not need heat -
if you’re usung a heat pump instead of gas, chances are it might have CAN bus like control, esphome will let you bridge that with wifi through a component or two, but maybe a simple relay will still be good enough.
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for mini splits - you might be able to control them through IR (simulate a remote)
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there’s also this opentherm protocol, but i don’t know anything about it
Logic
Basically go with home assistant, or go completely diy (complex).
Home assistant gives you a customizable UI, lots of pluggable of components, and it works with a ton of other opensource stuff. It’s got a large community.
If you want fancy displays and/or controllers (beyond your phone), there’s very little programmable nice looking stuff.
@wendell what did you go with for the new home or nothing selected yet?
OP honestly you dont need a fancy thermostat just a programmable schedule one is going to get you 98% of the way to where you want to be.
(Remember it takes time to change the temp of a house so having it trigger on when you get into the house will not be the best if you are trying to keep energy savings at a max(Dropping temp a ton when you aren’t there)
Honeywell makes this one that ties up to 3 thermostats together and is zwave. I did that but it’s not in yet
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tiny camera to read the “dumb” thermostat ?
and servo(s) connected to pi/arduino to change temperate setting?
1 on each floor? Does it average them temps in order to determine when to kick on or not? You have ducts that you can adjust the flow to each area?
no duct servos in this case. When you see that you usually only have 1 tstat but several temp sensors. In my case it is separate heatpumps for each area. There is an “outside” temperature sensor as part of the system so you can program e.g. a boiler to work in concert with a regular heatpump system, which only comes on when the outside temperature is otherwise low enough.
I have gas forced air w/heatpump for AC in one area, heatpump w/electric backup instead of gas in another area, and boiler all over. This type of thermostat is smart enough to run the boiler and the heatpump at the same time with a bit of fine-tuning.
Then the zwave interface means you can control zones. The bedrooms are all handled by boiler + mini-splits so no direct integration there.
That sounds like quite the set up. I wish I could go 100% heatpump but winter gets to cold for it to be worth it so when I upgrade going to do 80% efficient gas + heatpump AC / when its not super maybe heating (need to calc the cost difference)
(Kind of want radiant floor heating and mini split for each room, but idk if i can justify it)