Nice project, but only one suggestion, to put more temp sensors. Even today newest commercial house heating have that common lack, they measure temp just in one room where is temp sensor installed, and in other rooms are different temp and problem occurs. Good controller have multiple temp sensors should I say for each room, and all obtained data from sensors go to uC which later control furnace and electromagnetic valve on each radiator in each room.
If its not central heating system this project is right choice.