Whats the deal with my central heating?

Hi chaps. My heating boiler is a Glow-worm Ultracom 30cxi. I put it on the other day, set the timers (techy enough in itself!!) and waited. The rads warm nicely but the boiler never stops running. In other houses, it stops when the house is warm and goes on again when the place cools. This is on all the time, it gurgles and whistles...and scares me silly. Also the book says the range is 38 degrees C to 82 degrees C. It says C on the display too. My old one was set on 20 degrees C and thats fine. I thought they meant degrees F but it defo says C. Whats that about? Also, when its on hot water only it keeps firing up for a minute or so every now and then. I've contacted the landlord but no reply yet. Would be nice if I could say something intelligent to him raher than it doesn't work. Thanks for any help. x