This is a great project, but I'm a little concerned about two things:
1. Missing fail save mechanism
2. Insurance iddues.
Do you save really money by DIY? I counted briefly the money you have spent. I don't think you have really saved money.
Have a look on the Homematic IP system.
For almost the same money you could have a proven solution, running on nice looking wireless thermostats, accessible via your mobile phone, having a ready to use Homematic up server hosted at home.
The Homematic up server is based on raspberry pi. There are two versions, one ready to use, the other one you can use your own raspberry pi with their SW.
And you can extend the Homematic ip system with much more devices Homematic ip devices like connectors, security stuff, watering systems, whether sensors, fingerprint lock, etc.
And on the Homematic ip server every registered device is programmable, either visually by clicking on blocks or for more advanced guys using a script language.