I am interested in having a WiFi based thermostat that runs either Open Source firmware or firmware that I have written myself (which I would gladly share). I am capable of putting something together based on an ESP8266 or a raspberry pi. However, designing and building something that has a professional appearance that will meet spousal approval will likely be more of an issue. I am sure I could eventually climb the learning curve and get there with a lot of time and some trial and error but being honest, my interests don’t really lie in the area of designing pcb’s and plastic cases.
I would be fine with a pretty traditional looking thermostat with a small digital display and a couple of buttons. I would also consider something touchscreen based or nest-like in appearance although that’s definitely not a priority for me. I’m wondering if anyone has done any of the following and can make a recommendation:
Re-flashed a commercially available thermostat with custom firmware.
Modified the hardware of a commercially available thermostat to perhaps add a different micro controller which allowed it to be flashed with custom firmware (keeping the case, screen, relays, etc.)
Built a thermostat based on some published open hardware design that is available.
Was about to make a post wondering if there is a need for this, but found this one.
Is there still a need for this in general? I feel the same, that something is needed.
I can help on the hardware design, but the software would be rather involved and might need some serious efforts from folks. Basic HVAC - Heat, cool, scheduling, sensors, accessory control, user interface. Then, the smart part - HA integration, API.
I eventually settled on a radiotherm unit. It has a few issues but generally meets my needs.
There is also something called a hestiapi which is an open hardware design based around a raspberry pi zero and a touchscreen. I believe the standard image is based on openhab but obviously someone could use the hardware and put other software on it.
I was originally thinking that something based on an ESP8266 or ESP32 would be nice. I gather the demand for this is low though as my original post sat for over a year without a reply.
Just found your post as I keep trying to find something better than what I currently have. I have the radiotherm ct50, but I routinely lose contact with it, and have literally 1000+ repeated errors in my logs in just a few days: Updating radiotherm climate took longer than the scheduled update interval 0:01:00
I guess I’ll just follow this thread in case you ever come up with something
My server is in the furnace room, I could just tap into the thermostat wire and have HA control it through relays, temp sensors are already reported to HA to make decisions
That’s what I did about 3 years ago. Made a “temporary” Ethernet thermostat with an Arduino UNO, Ethernet shield and 4 relays shield. Just responds to MQTT commands furnace/heat, furnace/cool, furnace/blower .
I think the hacker/DIY route isn’t too bad as you guys have shown… it’s more a thermostat for “regular” users. Also in my case (cold winter), it needs to be quite reliable. Having a Pi with a failed update would be catastrophic during winter.
I was planning on doing this at some point in the future, and was going to leave the regular thermostat intact, then have a power control relay or switch that can disconnect the HA controlled relay module and return control to the regular thermostat. I have a triple pole relay that can bypass the heat/cold/blower wires simultaneously with a 12v trigger, then I could leave the regular therm powered so the time and schedule settings are intact on changeover
I was also going to use an industrial grade POE relay module for max reliability of the HA controlled system, but I might end up using an rpi with a relay hat, and add some temp probes to the ducting to detect if I have a furnace or ac failure, and could have the rpi control the rules regarding how long things run and if the heat or ac needs a cycle or rest period.
Having the timing control outside of HA also allows it to simplify, and have HA just send a “target” temp range and set of rules, and the therm will run itself… that seems like more work but would be awesome, then HA downtime/reboots or whatever will not impact reliability
My thoughts are (which may not apply to you) that a wall mounted thermostat is largely unnecessary. Once the temperature is set, it is set and a wall mount unit serves no purpose. A Generic Termostat with a few supporting automations (to switch between heating and cooling, presets, ec.) does the job.
Of course, I live alone and not in a family of thermostat fiddlers.
