Having looked over and over and over the available thermostat options available to me I am leaning heavily on the DIY kit available here: http://ihormelnyk.com/
(There is also a video demoing it (in quite good detail!) on youtube).
I believe I could use the MQTT version on the site.
My boiler is housed in the utility room right at the back of the house, I would need to be able to use the temperature from my lounge to control the boiler instead.
Not being up to speed with the use of MQTT (it’s my plan over Christmas) could I alter the sketch on the site to take the temperature from a second ESP8266 instead?
I also plan on creating my own TRV system to create heating zones, also using MQTT, I presume that by having the TRVs and Boiler control all tied into MQTT then expanding this system out to additional zones should be relatively easy?
The only downside I can see so far is that my boiler would be reliant on my Wifi. Could I add a button to the OpenTherm 8266 to over-ride the setting for an hour? (Also not up to speed with sketches…)
Or if the ESP8266 loses Wifi will it be completely inoperable including local control?
To display and adjust the temperature from the living room (like a traditional thermostat to keep the wife happy) I plan on setting up a tablet on the wall in kiosk mode with Node-Red thermostat (or lovelace) set up.
Feel free to point out any glaring issues you may spot that I’m not aware of…