why does my heater give out heat say 1.00am onwards?

It could be that one or more of the heater elements have burned out and are not heating the bricks up enough to store the heat, they should give out heat 24 hours. If you have a multimeter, you can check if the elements are dead. If it's a fairly modern heater, the elements are easy to replace, but some of the bricks have to be removed, just the front ones. If it' an ancient model best buy a new one. I can recommend CREDA, Go for the fully automatic ones, as once set, they never need to be altered, charging up as & when needed, these are what I have.

Homer
February 2010