Just FYI, to conserve energy consumption, it is a great idea to replace your old thermostats with the programmable thermostats. With this kind of thermostat you would be able to set the timer to go on and off at certain times of the day. With this action, you would be saving so much on electricity, and we all know the Eskom problem we have. For example: You wake up at 5am and leave the house at 7am, so then you set the thermostat to go on for these 2 hours. Then you would set it to a lower temperature as no one is home, it gets set again to go on when everyone returns home, say 5pm to 10pm. So lets say you have a room of 20m2 which means you would have a 2kw heater installed. So now to calculate:

1 - Eskom rate ( R1,50 per kw )
2 - Your underfloor heater ( 2kw )
3 - Running hours ( set by the thermostat ), in this case 7 hours

R1,50 x 2kw x 7 hrs = R21 for the day x 30 days = R630 per month.

So, with upgrading to programmable thermostats, this is how you could save money. With the old mechanical thermostats, this figure can double or triple. This post might be a bit late, but I thought to prepare you for next winter since everyone is getting their year end bonus.