How can i fix my Radiators?

It may be that the upstairs radiators are using up all the available heat before the pumped radiator water reaches the downstairs rads...

Turn the upstairs rads fully off - if downstairs rads now start to warm up you know the likely cause.

You can balance the radiators by adjusting the lock shield valves (closing off the outlet valves a bit) particularly on the upstairs rads - see...

http://www.miketheboilerman.com/balancing.htm

You can increase the temperature of the water from the boiler a bit but not too much else the tap water may become too hot - you can sometimes speed up the circulating pump to get the water around the system a little quicker.

This answer is close to worthless because I have no specific expertise in heating systems - but it might work...

Good luck...

Peccavi
October 2009