Another noob question: see the attached image of my thermostat. Would it be possible to switch it for a smart one? What would I have to check? If it is possible, what would you recommend? If is don’t want any 3rd party app or account?
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This suggestion depends on your skill level and desire to be completely free of corporate bs.
The ‘smart’ is already in home assistant. You do not need a smart thermostat at all. Instead you need temperature/humidity sensors and actuators for your HVAC system. There are several decent smart climate control integrations already and a library for PID control if you want to make your own control automations.
Of all the smart things out there, a thermostat is completely unnecessary. The only solid reason to buy one is convenience, if one is just not into thinking about it too much.
If privacy and autonomy are a priority, however, this is low-hanging fruit to declare independence from corporates who like to rummage through your underwear drawer.
We (UK) recently put in a Tado X thermostat, which uses Matter over WiFi - as soon as I work out how to setup Matter server in a docker, I’m hoping that will connect with HA 🤞🤞🤞
An ESP8266 running ESPHome and a relay would work here. It’s basically on or off. Then you could pull temperature information in from multiple temp sensors around your home.
I do something similar for some solar air heaters I built.
Despite the name it’s not a simple on/off that can be done with a relay. Those 2 wires also provide power to the thermostat unit. I’d first try to find more information about how these thermostats report demand to the boiler before using a relay.
I’ve also seen someone that simply replaced the NTC/PTC on their existing thermostat with some ESP circuit so they basically controlled what the thermostat “sees”. Want more heat? Tell the thermostat that it’s 5℃ in the room. Want the boiler to stop? Simulate a cozy 30℃.
The power being provided to the unit is just a side effect. More than likely 24vdc and a set of contacts. If you were to wire a simple toggle switch in and flip it on the heat would turn on.
I’ve dealt with hundreds of thermostats they all work in a similar fashion the new ones just use multiple relays with a single power wire. The old school thermostats just used bimetal contacts or clock springs with a mercury relay. Modern ones use electromechanical or solid state relays. This includes things like the nest thermostats.
The Junkers boiler at my previous place had an emergency mode where it was heating when the contacts were open. Even their simplest thermostats put a load on the wires depending on how much heat is required - so it doesn’t go full blast when you are only slightly under the target temperature.
So, this all depends on your specific boiler. While it might work with a simple relay, it might be far from optimal in terms of energy efficiency and wear&tear of the boiler.
That’s a Honeywell T87G1006 “On/Off” thermostat. “On/Off” meaning that it can signal to the boiler whether more heat is needed or not. Boilers of that time may also be compatible with the OpenTherm protocol as there’s a similar model that also speaks OpenTherm.
The easiest way to go about this is probably to look for a more modern thermostat that’s compatible with your boiler but also provides some interface for remote control from your Home Assistant.
Just switched to a Honeywell T6 Zwave (model TH6320ZW2003) thermostat and really like it. It’s a big step up from my old wifi thermostat. There are some nice features like a humidity sensor and adjustable backlight, but the feature we like best is the Circulation fan mode that runs the furnace fan a certain percentage of the time even if the system isn’t heating or cooling. This has made a significant different in our comfort level and we notice when the fan isn’t set to Circulation.
Since it’s locally controlled, settings changes take effect immediately without the delay we regularly had with our old wifi Honeywell. Programming was more involved than a regular smart thermostat, but not overwhelming. It can be powered by a C wire or by batteries. Ebay has open box, like new models.
Where do you live? What type of unit do you have?
I just got the Meross Smart thermostat running. (The installer literally just left 10 minutes ago.) I had to call an HVAC person to help me install it because I didn’t have the wiring setup properly for a wifi thermostat.
Maybe call an HVAC company and tell them you want to install a smart thermostat, but you’re unsure if your system is compatible. (Maybe they can do some HVAC maintenance while they’re in there too.)
I’m using it with an HA Yellow with a Z-Wave radio. It’s flawless. I don’t know if it can be adapted for 2 wires but it definitely works with batteries.
The product is no longer available for sale.
Totally agree. Rock solid.
I looked into this a few years ago. At that time, if you had a “c wire”, there were several options that would work directly with HA.
I don’t have a C Wire so that didn’t help me.
Without a c wire, I was only able to find a single option. A “Sensi” brand that could run on batteries, but wouldn’t work directly with HA. Tou had to control it though Amazon Alexa or through their app. Neither option turned out to be particularly reliable.
You can also run a Nest thermostat without a C wire and it’s matter compatible now.
Ecobee units have a power splitter that will let you run with a 4-wire setup (standard Heat/Cool/Fan/Common)
You’re going to hampered in your choices by the lack of wires. You have an old 2 wire setup. Most nowadays want 3. Some can handle 2 wires, look for thermostats that don’t need a “c wire” or “control wire”.
This. But…
The smart thermostat will come with a c wire. It’s an adapter that can plug into a normal outlet and then run to your thermostat. Depending on your level of DIY, you can hide the wire (or the entire adapter) inside the wall to make it prettier.
Recently was given an Ecobee smart thermostat. Ecobee does not have a great integration for Home Assistant, but Home Assistant can act like an Apple HomeKit hub, and if you provision the smart thermostat through that, it is entirely local.
+1 for this. Very solid using the homekit method. If you use the default integration, I believe it’s cloud connected.
Adding it via HomeKit into home assistant is solid and has the added bonus is that the occupancy/motions sensors get exposed to HA. They’re very responsive when someone walks into a room; I have them triggering lighting.
