depends on what you set the temp to really

if you are after a regular temp to set accodring to the thermometer hanging in the house aroundabout the 20-25 mark is what you've be looking for, but our heater is set to 50C when it's on overnight and, if it's cold then we crank it up to 60C

it also depends on how many radiators you have and the length of the pipes etc

obviously the hotter you set it the longer it takes to get to that temp and the more energy you will use

btw, how are you measureing the temp?