frankly ball cocks and simply app of the day..
heating controls can be fantastically elaborate as the above proves.. but simply what is the point?
of the hundreds of homes i visit each year only two actively monitor and know and understand thier gas usage ( thier both retired accountants)
most measure thier gas usage in how much they spend on monthly direct debit payments and most of them cannot quote accurately
most homes today have room and radiator thermostats and the great majority dont understand care how to use them
the majority of homes heat is managed by using a room stat as an on / off switch..
if your in a position where you believe 90% of homes use the internet and that believe that most people have a mobile phone.. dream on.. i live and work in the real world where folks want an on off switch for thier heating..